whytheincreasingtrendofsummerrainfallovernorthchina … · 2019. 10. 3. · researcharticle...
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Research ArticleWhy the Increasing Trend of Summer Rainfall over North ChinaHas Halted since the Mid-1990s
Haiwen Liu 1 Jiarui Miao1 Kaijun Wu 1 Mengxing Du 1 Yuxiang Zhu 2
and Shaoyu Hou3
1Department of Aviation Meteorology Civil Aviation University of China Tianjin 300300 China2CMA Training Center China Meteorological Administration Beijing 100081 China3College of Atmospheric Sciences Chengdu University of Information Technology Chengdu 610225 China
Correspondence should be addressed to Kaijun Wu kjwucauceducn
Received 3 October 2019 Revised 12 December 2019 Accepted 21 December 2019 Published 27 January 2020
Academic Editor Anthony R Lupo
Copyright copy 2020 Haiwen Liu et al +is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
Previous studies indicate that the summer (July-August) rainfall over North China has decreased since the mid-1970s due to theweakening of East Asian summer monsoon (EASM) However this study firstly discovers the new evidences that the summerrainfall over North China had a significant increasing tendency during 1979ndash1996 since 1997 this increasing tendency has haltedwhile more summer droughts occurred over North China One important cause for the halted increasing tendency over NorthChina is the interdecadal decrease of the westerly water vapor transport during 1997ndash2016 in addition to the weakened EASM+edecrease of the westerly water vapor transport during 1997ndash2016 was due to the interdecadal warming over Lake Baikal +einterdecadal warming in the upper troposphere at 200 hPa forced the weakening of the upper-level zonal winds since 1997 whichresulted in the anomalous descending flow over the north side of North China and the halted precipitation trend in North China
1 Introduction
North China a highly populated region is located innorthern China [1] +e summer (July-August) meanrainfall over North China has exhibited strong interdecadalvariability [2ndash8] North China experienced a relatively wetperiod from the 1950s to 1964 and a dry period since the endof 1970s [9 10] when the droughts have greatly affected localagriculture industry and even the drinking water [11]Except the interdecadal shift of summer rainfall over easternChina in the late 1970s [10 12ndash14] another decadal shiftover East Asia in the mid-1990s has also been investigated[15ndash19] For example Chen et al [20] found that southernChina summer rainfall experienced a remarkable increase inthe early 1990s Wu et al [21] discovered a pronouncedinterdecadal change in summer rainfall over southern Chinaaround 199293 with persistent negative anomalies during1979ndash1992 and positive anomalies during 1993ndash2002
Many possible causes of the interdecadal shift of theeastern China rainfall pattern in the late 1970s are
investigated [10 12ndash14] for example the thermal contrastbetween the land and ocean by the large-scale temperaturevariations [2 22] the sea surface temperature (SST) vari-ations in the equatorial central and eastern Pacific [5] therole of the air-sea interaction in the middle latitudes [23] theArctic sea-ice variations in winter [24] the North AtlanticOscillation (NAO) and North Pacific Oscillation (NPO)variation [25] the interdecadal change of EASM [12] thewestern Pacific subtropical high (WPSH) over the sub-tropical regions of East Asia [4 26] the interdecadal coolingin the upper troposphere and lower stratosphere over EastAsia [27] the Pacific decadal oscillation (PDO) [28ndash30] andthe thermal effect of black carbon aerosols over Asia [31]
Although the consensuses on the interdecadal summerdrought over North China have beenmade in the mentionedstudies above along with the development of the updatedrainfall data with higher spatial resolutions how did thesummer rainfall over North China change in the recentdecades is still of great concern in the climate researchcommunity It is well known that there are four vapor inflow
HindawiAdvances in MeteorologyVolume 2020 Article ID 9031796 10 pageshttpsdoiorg10115520209031796
corridors the southwest corridor the South China Sea thesoutheast corridor and northwest corridor from the mid-latitude westerlies to China [32 33] In addition to the greatimportance of the summer monsoon water vapor transportto North China [34] which boundary is also crucial to themoisture budget over North China associated with inter-decadal variations of the summer rainfall there To addressthese issues this study will investigate a new interdecadalcharacteristic of the summer rainfall over North China usingthe latest precipitation data and analyze the possible causes
+e organization of the paper is as follows +e datasetsand methodology are described in Section 2 Section 3presents the interdecadal variability of summer rainfall overNorth China between the periods of 1979ndash1996 and1997ndash2016 and further analyzes the interdecadal variationsof atmospheric circulation water vapor budget and surfaceair temperature (SAT) A summary is given in Section 4
2 Datasets and Methods
+e existing criteria of the precipitation in North China [9]the averaged summer (July-August) precipitation of the 17gauge-based stations chosen from 160 stations in Chinafrom 1951 to 2016 are used to reveal the interdecadalvariability of summer rainfall over North China +e 17meteorological stations are Chengde Beijing Tianjin Shi-jiazhuang Dezhou Xingtai Anyang Yantai QingdaoWeifang Jinan Linyi Heze Zhengzhou Changzhi Taiyuanand Linfen which are widely used to represent rainfall overNorth China [9] and mostly located within the domain(35degNndash41degN 110degNndash122degE) in Figure 1
To further demonstrate the robustness of the inter-decadal variability of the summer rainfall over North Chinathe full data monthly product version 2018 of Global Pre-cipitation Climatology Centre (GPCC) is also used +eGPCC with a spatial resolution of 10deg times10deg is derived fromquality-controlled station data from 1979 to 2016 and iswidely used in the study of the interdecadal variation of localor regional rainfall [35ndash37]
To investigate the interdecadal variations of the summerrainfall over North China using two types of the precipi-tation data two indexes of summer precipitation over NorthChina (ISPNC) are defined One index is the normalized 17-station averaged summer precipitation referred to as theISPNC17 [9] +e other one is the normalized regional av-eraged summer precipitation in 35degNndash41degN 110degNndash122degEusing GPCC data defined as ISPNCGPCC
To investigate the interdecadal variabilities of the atmo-spheric circulation the European Centre for Medium-RangeWeather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) is used [38] +e gridded (075deg times 075deg) monthlyERA-Interim data during 1979ndash2016 are applied in this studyVariables include horizontal winds in 850 hPa geopotentialheight in 500 hPa 2m surface air temperature (SAT) andvertical integral of water vapor flux To verify the interdecadalvariabilities of the atmospheric circulation the monthly JRA-55 data during 1979ndash2013 are also used [39] Two re-analysisdatasets are highly consistent For brevity we only show theERA-Interim results Mann-Kendall (M-K) method is used to
detect the trend and abrupt point of the time series [40 41]+e statistical significance of the composite analysis and trendanalysis is tested using Studentrsquos t-test [42]
+e water vapor transport (M) via each boundary iscalculated by
M 1113946L
Qrarr
times nrarrdl (1)
Qrarr
is vertical integral of water vapor flux while L isboundary line and dl is the unit boundary length n
rarr is theinward-pointing normal vector of the boundaries of thetarget region [43]+e net budget of the regional water vaportransport is calculated by each boundary +e positive re-gional water vapor budget indicates the net atmosphericwater vapor flux from outside and the abundant precipitablewater within the region
3 Results
31 Interdecadal Variability of Summer Rainfall over NorthChina Figure 2(a) shows time series of ISPNC17 during1979ndash2016 Obviously summer rainfall of North China hadan increasing tendency from 1979 to 1996 With the rate of0101year the tendency during 1979ndash1996 passed the sig-nificance test at the 95 confidence level suggesting thatsummer rainfall of North China had a significant increasingtendency during the period +is interdecadal characteristicis very different from the previous studies [2ndash8] whichmainly focused on the interdecadal decrease of the summerrainfall in North China since the mid-1980s [5 6 9] Fewstudies discover that there was an obviously increasingtendency during 1979ndash1996 Unfortunately the increasingtendency has halted since 1997 +en North China enteredthe drought period with several persistent droughts ac-companied by severe effects on industry and agriculture overNorth China [5 44]
The North China region
100degE 105degE 110degE 115degE 120degE 125degE 130degE 135degE30degN
35degN
40degN
45degN
50degN
0m 1000m 2000m 3000m 4000m 5000m 6000m
Figure 1 Locations of the 17 weather stations (blue circles) inNorth China and the region of North China (35degNndash41degN110degEndash122degE blue rectangle) +e shading represents the surfaceelevation surrounding North China in meters
2 Advances in Meteorology
+e time series of ISPNCGPCC in Figure 3(a) also showsimilar increasing tendency during 1979ndash1996 with thetrend rate of 0094year which also reaches the 95 con-fidence level according to Studentrsquos t-test +is increasingtendency has also halted since 1997 So the gauge-basedstation precipitation data and the grid precipitation data ofGPCC both show that summer rainfall over North Chinahad an obvious increasing tendency during 1979ndash1996 andhas halted since 1997
To further investigate the interdecadal shift of thesummer rainfall over North China Mann-Kendall testmethod was used to detect the abrupt point of ISPNC17 inFigure 2(b) +ere is a cross point between the backwardstatistic rank series and forward statistic rank series sug-gesting that summer rainfall over North China experienced adistinct interdecadal change around 1996 Since 1997 therehave been more droughts occurring in North China Asevere drought attacking North China in 2014 also indicatedthat North China has become drier in recent years [44]Figure 3(b) further verifies the interdecadal shift of thesummer rainfall over North China using grid precipitationdata of GPCC
+e differences of summer rainfall by 1997ndash2016 meanminus 1979ndash1996 mean over Northeast Asia further verifythe interdecadal variability of summer rainfall over NorthChina in Figure 4 Whether using gauge-based station dataor using the grid precipitation data of GPCC the significantnegative summer rainfall differences are both found overNorth China which is statistically significant at the 95confidence level by Studentrsquos t-test Meanwhile the mainwetter regions are located in the Huaihe River valley whichsuggests that the wetter belt has moved northwards fromsouthern China [45] Meanwhile the spatial pattern of
summer rainfall variation since 1997 has been different fromthe so-called pattern of southern flood and northern droughtsince the end of 1970s [26 27 46 47]
32 e Interdecadal Variability of the AtmosphericCirculation East Asia is dominated by a typical monsoonclimate [45 48] +e summer precipitation change overeastern China affected by the EASM greatly is very sig-nificant on the interannual and interdecadal timescales [10]To further study the causes of drier North China Figure 5(a)shows the difference of the 850 hPa wind during 1997ndash2016with respect to the period of 1979ndash1996 As Figure 5(a)shows North China is dominated by the anomalousnortherly wind from Lake Baikal which suggests that theEASM is weaker in 1997ndash2016 compared with 1979ndash1996Weaker summer monsoon favors the less precipitation overNorth China [12 44]
Meanwhile an anomalous anticyclonic circulationdominates the region of Lake Baikal (40degNndash60degN80degEndash120degE) significantly +e anticyclonic circulation sys-tem over Lake Baikal is also vital for the variation of summerrainfall over North China [8 49] +e anomalous easterlyflow and northerly flow from the anomalous anticyclone areclosely associated with the water vapor flux anomaly overNorth China In Figure 5(b) an anomalous anticycloniccenter of the water vapor flux is also observed over LakeBaikal North China is dominated by the anomalousnortheast water vapor flux+e difference of water vapor fluxover Lake Baikal and North China during two periods issignificant and reaches the 95 confidence level Obviouslythe anomalous northeast water vapor flux from Lake Baikalis beneficial to the interdecadal drought over North China
Mean = 005Trend = 0101Year (98) Mean = minus004
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
(a)
1980 1985 1990 1995 2000 2005 2010 2015ndash5
0
5
UB
UF
(b)
Figure 2 (a)+e time series of ISPNC17 during 1979ndash2016+e horizontal dashed lines indicate the interdecadal mean while solid line from1979 to 1996 indicates the interdecadal trend and the vertical dashed lines indicate the interdecadal shift points (b)+eMann-Kendall testof ISPNC17 (green dotted line shows backward statistic rank series and blue dotted line shows forward statistic rank series) Two black linesshow 95 confidence level
Advances in Meteorology 3
To further investigate which boundary of water vaportransport is critical for interdecadal drought over NorthChina the water vapor transports via four boundaries arecalculated As shown in Figure 6 the anomalous input watervapor transports are via east and north boundary which isconsistent with the fact that North China is dominated bythe northeast flow and northeast water vapor flux in Fig-ure 5 +e interdecadal differences of the water vaportransport via the east boundary and north boundary areinput 914times106 kgs and 2170times106 kgs and the inter-decadal differences of the water vapor transport via the westboundary and south boundary are output 1462times106 kgsand 1847times106 kgs respectively
Because the sum of output water vapor transport isgreater than the sum of input water vapor transport the
difference of water vapor budget over North China isnegative (-225times106 kgs) Numerous studies focused on thefact that weaker summer monsoon flow is responsible forless water vapor transport via south boundary and lesssummer rainfall in North China [34] +is study furtherpoints that water vapor transport via west boundary is alsoimportant for the less summer rainfall in North China +ewater vapor transport via the west boundary is crucial for thesummer rainfall over eastern China [32 33] In the JRA-55data the differences of water vapor transport via fourboundaries of North China have same directions with thosein ERA-Interim data but there is a weak positive differenceof net water vapor budget which is not consistent with theresults in ERA-Interim data +e weak positive difference ofwater vapor budget is against the fact of less rainfall over
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Figure 4 Difference of summer rainfall by 1997ndash2016 mean minus 1979ndash1996 mean for (a) 160 stations and (b) GPCC +e shadingindicates statistically significant difference at the 95 confidence level based on Studentrsquos t-test +e box shows North China
Mean = 016Trend = 0094Year (95) Mean = ndash015
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Figure 3 (a) Same as Figure 2(a) but for the ISPNCGPCC (b) Same as Figure 2(b) but for the ISPNCGPCC
4 Advances in Meteorology
North China +e reason for the weak positive difference ofwater vapor budget over North China in JRA-55 data isworthy of further study
+ere are also obvious interdecadal variations in low andmiddle troposphere As Figure 7(a) shows the anomalouspositive geopotential height at 500 hPa is observed over LakeBaikal +e anomalous positive geopotential height benefitsthe anomalous northerly wind in eastern China +eanomalous positive geopotential height at 500 hPa is asso-ciated with the interdecadal warming over Lake Baikal +einterdecadal warming over Lake Baikal happens not only inthe surface in Figure 7(b) but also in 200 hPa in Figure 8(a)+e interdecadal warming in 200 hPa reduces the meridionalcontrast of air temperature nearby Lake Baikal +ereby thenegative difference of zonal wind exists around 40degN sug-gesting the weakening 200 hPa zonal winds in the inter-decadal time scales As Figure 8(b) shows the northward andwestward movement of the 200 hPa zonal winds center over
the northwest of North China during 1997ndash2016 comparedwith 1979ndash1996 suggests the interdecadal weakening of the200 hPa zonal winds +e strength of the upper-level zonalwinds has great contribution to the precipitation over NorthChina [50 51] +e anomalous descending motion overNorth China in Figure 9 further demonstrates the weakenedpumping role of the 200 hPa zonal winds over North China+e interdecadal weakening of ascending motion andinterdecadal reduction of the water vapor flux over NorthChina result in the interdecadal reduction of precipitationover North China
33e Possible Mechanism of the Interdecadal Variability ofSummer Rainfall over North China +e interdecadalwarming of Lake Baikal has a significant impact on thesummer rainfall over North China [8 48 52] which is alsoconfirmed in Figure 7(b) To discover the abrupt point of the
2170 times 106
1847 times 106
1462 times 106 914 times 106
ERA (1997ndash2016 minus 1979ndash1996)
ndash225 times 106
Unit kgs
(3525Nndash405degN 11025Endash1215degE)
Figure 6 Difference of water vapor budget via each boundary of North China by 1997ndash2016meanminus 1979ndash1996mean (unit kgs) Darkarrows indicate the direction of horizontal water vapor transport difference across each boundary Number in box indicates the difference ofwater vapor budget for North China
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Figure 5+e difference by 1997ndash2016meanminus 1979ndash1996mean for (a) 850 hPa horizontal winds (units ms) and (b) vertical integral ofwater vapor flux (unit kgms) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test+e red boxshows North China +e green box shows the region of Lake Baikal (40degNndash60degN 80degEndash120degE) +e white region outlines surface pressurelower than 850 hPa
Advances in Meteorology 5
warming of Lake Baikal the standardized time series of theaveraged summer SAT over Lake Baikal (40degNndash60degN80degEndash120degE) is shown in Figure 10(a) +e feature of theinterdecadal and interannual variability of SAT over LakeBaikal is apparent Mann-Kendall test method is used toinvestigate accurate abrupt point of the SATover Lake Baikalin Figure 10(b) +e abrupt year of the SATover Lake Baikalis close to the abrupt year of the summer rainfall over NorthChina
+e SAT over Lake Baikal and the summer rainfall overNorth China have experienced the interdecadal changes
since the mid-1990s +e negative correlation existing be-tween the SATover Lake Baikal and the summer rainfall overNorth China [49] suggests that the interdecadal warming ofLake Baikal contributes to the interdecadal less summerrainfall over North China+e interdecadal warming of LakeBaikal is observed not only in the lower troposphere inFigure 7(b) but also in the upper troposphere in Figure 8(a)+e interdecadal warming of Lake Baikal results in not onlythe anomalous anticyclonic circulation and anomalouspositive geopotential height over Lake Baikal in the lower andmiddle troposphere but also the weakening of the zonal wind
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Figure 7 Same as Figure 5 but for (a) 500 hPa geopotential height (unit gpm) and (b) SAT (unit degC)
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Figure 8 (a) Same as Figure 5 but for 200 hPa zonal winds (contours unit ms) and temperature (shading unit degC) +e difference oftemperature in blue box with black dots is statistically significant at the 95 confidence level according to Studentrsquos t-test +e difference ofzonal winds with black cross is statistically significant at the 95 confidence level according to Studentrsquos t-test (b) 200 hPa zonal winds (unitms) in JA of 1979ndash1996 mean (black contours) and 1997ndash2016 mean (white contours) +e shading is the climatic mean of 200 hPa zonalwinds during 1979ndash2016 +e black box shows North China +e green box shows the region of Lake Baikal
6 Advances in Meteorology
in the upper troposphere Obviously the anomalous anti-cyclonic circulation over Lake Baikal is beneficial to less watervapor transport from the monsoon flow and the westerliesMeanwhile the weakening of the zonal wind in the uppertroposphere favors the weakening of the ascending motionand further results in the weakening of the pumping effects ofthe zonal winds in the upper troposphere +e interdecadalweakening of the ascending motion and interdecadal re-duction of the water vapor transport to North China directlylead to the interdecadal drought over North China
4 Summary and Discussion
Using the 17-station rainfall and the new GPCC full datamonthly product precipitation data sets the interdecadal
variations of the summer rainfall over North China since themid-1990s are firstly discovered in this paper +e possiblecauses such as the interdecadal variations of the atmosphericcirculation and the water vapor budget are discussed+emajormechanisms are shown in Figure 11 and summarized as follows
Summer rainfall over North China had an increasingtendency during 1979ndash1996 since 1997 this increasingtendency has halted and more summer droughts occurredover North China
+e SAT over Lake Baikal and the summer rainfall overNorth China have had interdecadal abrupt since the mid-1990s +e interdecadal warming of Lake Baikal is beneficialto the interdecadal less summer rainfall over North China
+e intense interdecadal warming of Lake Baikal resultsin not only the anomalous anticyclonic circulation and
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0Figure 9 Latitude-height cross section of difference of vertical velocity along 11625degE in JA by 1997ndash2016meanminus 1979ndash1996mean (unit10minus 2 Pas) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test +e red line shows North China
Mean = ndash074
Trend = 0069year (96)
Mean = 06
1980 1985 1990 1995 2000 2005 2010 2015
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(a)
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Figure 10 (a) Same as Figure 2(a) but for the summer SAT over Lake Baikal (b) Same as Figure 2(b) but for the summer SAT overLake Baikal
Advances in Meteorology 7
anomalous positive geopotential height over Lake Baikal inthe lower and middle troposphere but also the weakening ofthe zonal wind in the upper troposphere +e anomalousanticyclonic circulation in the lower troposphere over LakeBaikal results in less water vapor transport from the mon-soon flow and the westerly flow +e weakening of the zonalwind in the upper troposphere favors the weakening of theascending motion and the pumping effects of the zonalwinds in the upper troposphere+e interdecadal weakeningof the ascending motion and the less interdecadal watervapor transport result in the interdecadal drought in NorthChina
In addition to the contribution of the less water vaportransport from weakened monsoon flow to the summerrainfall over North China the interdecadal reduction of thewater vapor transport from western boundary to NorthChina is also responsible for the halted rainfall tendencyover North China since the mid-1990s which is usuallyignored
+ere are many other factors that also contribute to theinterdecadal variation of the summer rainfall over NorthChina [6] such as Pacific decadal oscillation [52] arcticsea ice [44] and Tibet Plateau snow cover [53] +esefactors and climate model verification are worthy offurther study
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work is supported by the Strategic Priority ResearchProgram of Chinese Academy of Sciences (XDA20100304)the State Key Program of the National Natural ScienceFoundation of China (41475051 41875111) the StartingFoundation of the Civil Aviation University of China(2016QD05X) and the Research Foundation of the CivilAviation University of China (3122015D019)
References
[1] L Han S Li and N Liu ldquoAn approach for improving short-term prediction of summer rainfall over North China bydecomposing interannual and decadal variabilityrdquo Advancesin Atmospheric Sciences vol 31 no 2 pp 435ndash448 2014
[2] Z Yan J Ji and D Ye ldquoNorthern hemispheric summerclimatic jump in the 1960rsquos (I)mdashrainfall and temperaturerdquoScience in China (Series B) vol 33 no 9 pp 1092ndash1101 1990
[3] A Yatagai and T Yasunari ldquoTrends and decadal-scale fluc-tuations of surface air temperature and precipitation overChina and Mongolia during the recent 40 year period (1951-1990)rdquo Journal of the Meteorological Society of Japan Ser IIvol 72 no 6 pp 937ndash957 1994
[4] T Nitta and Z-Z Hu ldquoSummer climate variability in Chinaand its association with 500 hPa height and tropical con-vectionrdquo Journal of theMeteorological Society of Japan vol 74no 4 pp 425ndash445 1996
60degE70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
60deg E70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
20degN
30degN
40degN
50degN
60degN
1997ndash2016 minus 1979ndash1996
850hPa
200hPa
Upper-level jet stream
Lake Baikal
North ChinaDrier
Anomalous anticyclone
Weakened
Anomalousdescendingflows
Figure 11 Schematic diagram of mechanism for the halt of the increasing trend of summer rainfall over North China since the mid-1990s
8 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
corridors the southwest corridor the South China Sea thesoutheast corridor and northwest corridor from the mid-latitude westerlies to China [32 33] In addition to the greatimportance of the summer monsoon water vapor transportto North China [34] which boundary is also crucial to themoisture budget over North China associated with inter-decadal variations of the summer rainfall there To addressthese issues this study will investigate a new interdecadalcharacteristic of the summer rainfall over North China usingthe latest precipitation data and analyze the possible causes
+e organization of the paper is as follows +e datasetsand methodology are described in Section 2 Section 3presents the interdecadal variability of summer rainfall overNorth China between the periods of 1979ndash1996 and1997ndash2016 and further analyzes the interdecadal variationsof atmospheric circulation water vapor budget and surfaceair temperature (SAT) A summary is given in Section 4
2 Datasets and Methods
+e existing criteria of the precipitation in North China [9]the averaged summer (July-August) precipitation of the 17gauge-based stations chosen from 160 stations in Chinafrom 1951 to 2016 are used to reveal the interdecadalvariability of summer rainfall over North China +e 17meteorological stations are Chengde Beijing Tianjin Shi-jiazhuang Dezhou Xingtai Anyang Yantai QingdaoWeifang Jinan Linyi Heze Zhengzhou Changzhi Taiyuanand Linfen which are widely used to represent rainfall overNorth China [9] and mostly located within the domain(35degNndash41degN 110degNndash122degE) in Figure 1
To further demonstrate the robustness of the inter-decadal variability of the summer rainfall over North Chinathe full data monthly product version 2018 of Global Pre-cipitation Climatology Centre (GPCC) is also used +eGPCC with a spatial resolution of 10deg times10deg is derived fromquality-controlled station data from 1979 to 2016 and iswidely used in the study of the interdecadal variation of localor regional rainfall [35ndash37]
To investigate the interdecadal variations of the summerrainfall over North China using two types of the precipi-tation data two indexes of summer precipitation over NorthChina (ISPNC) are defined One index is the normalized 17-station averaged summer precipitation referred to as theISPNC17 [9] +e other one is the normalized regional av-eraged summer precipitation in 35degNndash41degN 110degNndash122degEusing GPCC data defined as ISPNCGPCC
To investigate the interdecadal variabilities of the atmo-spheric circulation the European Centre for Medium-RangeWeather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) is used [38] +e gridded (075deg times 075deg) monthlyERA-Interim data during 1979ndash2016 are applied in this studyVariables include horizontal winds in 850 hPa geopotentialheight in 500 hPa 2m surface air temperature (SAT) andvertical integral of water vapor flux To verify the interdecadalvariabilities of the atmospheric circulation the monthly JRA-55 data during 1979ndash2013 are also used [39] Two re-analysisdatasets are highly consistent For brevity we only show theERA-Interim results Mann-Kendall (M-K) method is used to
detect the trend and abrupt point of the time series [40 41]+e statistical significance of the composite analysis and trendanalysis is tested using Studentrsquos t-test [42]
+e water vapor transport (M) via each boundary iscalculated by
M 1113946L
Qrarr
times nrarrdl (1)
Qrarr
is vertical integral of water vapor flux while L isboundary line and dl is the unit boundary length n
rarr is theinward-pointing normal vector of the boundaries of thetarget region [43]+e net budget of the regional water vaportransport is calculated by each boundary +e positive re-gional water vapor budget indicates the net atmosphericwater vapor flux from outside and the abundant precipitablewater within the region
3 Results
31 Interdecadal Variability of Summer Rainfall over NorthChina Figure 2(a) shows time series of ISPNC17 during1979ndash2016 Obviously summer rainfall of North China hadan increasing tendency from 1979 to 1996 With the rate of0101year the tendency during 1979ndash1996 passed the sig-nificance test at the 95 confidence level suggesting thatsummer rainfall of North China had a significant increasingtendency during the period +is interdecadal characteristicis very different from the previous studies [2ndash8] whichmainly focused on the interdecadal decrease of the summerrainfall in North China since the mid-1980s [5 6 9] Fewstudies discover that there was an obviously increasingtendency during 1979ndash1996 Unfortunately the increasingtendency has halted since 1997 +en North China enteredthe drought period with several persistent droughts ac-companied by severe effects on industry and agriculture overNorth China [5 44]
The North China region
100degE 105degE 110degE 115degE 120degE 125degE 130degE 135degE30degN
35degN
40degN
45degN
50degN
0m 1000m 2000m 3000m 4000m 5000m 6000m
Figure 1 Locations of the 17 weather stations (blue circles) inNorth China and the region of North China (35degNndash41degN110degEndash122degE blue rectangle) +e shading represents the surfaceelevation surrounding North China in meters
2 Advances in Meteorology
+e time series of ISPNCGPCC in Figure 3(a) also showsimilar increasing tendency during 1979ndash1996 with thetrend rate of 0094year which also reaches the 95 con-fidence level according to Studentrsquos t-test +is increasingtendency has also halted since 1997 So the gauge-basedstation precipitation data and the grid precipitation data ofGPCC both show that summer rainfall over North Chinahad an obvious increasing tendency during 1979ndash1996 andhas halted since 1997
To further investigate the interdecadal shift of thesummer rainfall over North China Mann-Kendall testmethod was used to detect the abrupt point of ISPNC17 inFigure 2(b) +ere is a cross point between the backwardstatistic rank series and forward statistic rank series sug-gesting that summer rainfall over North China experienced adistinct interdecadal change around 1996 Since 1997 therehave been more droughts occurring in North China Asevere drought attacking North China in 2014 also indicatedthat North China has become drier in recent years [44]Figure 3(b) further verifies the interdecadal shift of thesummer rainfall over North China using grid precipitationdata of GPCC
+e differences of summer rainfall by 1997ndash2016 meanminus 1979ndash1996 mean over Northeast Asia further verifythe interdecadal variability of summer rainfall over NorthChina in Figure 4 Whether using gauge-based station dataor using the grid precipitation data of GPCC the significantnegative summer rainfall differences are both found overNorth China which is statistically significant at the 95confidence level by Studentrsquos t-test Meanwhile the mainwetter regions are located in the Huaihe River valley whichsuggests that the wetter belt has moved northwards fromsouthern China [45] Meanwhile the spatial pattern of
summer rainfall variation since 1997 has been different fromthe so-called pattern of southern flood and northern droughtsince the end of 1970s [26 27 46 47]
32 e Interdecadal Variability of the AtmosphericCirculation East Asia is dominated by a typical monsoonclimate [45 48] +e summer precipitation change overeastern China affected by the EASM greatly is very sig-nificant on the interannual and interdecadal timescales [10]To further study the causes of drier North China Figure 5(a)shows the difference of the 850 hPa wind during 1997ndash2016with respect to the period of 1979ndash1996 As Figure 5(a)shows North China is dominated by the anomalousnortherly wind from Lake Baikal which suggests that theEASM is weaker in 1997ndash2016 compared with 1979ndash1996Weaker summer monsoon favors the less precipitation overNorth China [12 44]
Meanwhile an anomalous anticyclonic circulationdominates the region of Lake Baikal (40degNndash60degN80degEndash120degE) significantly +e anticyclonic circulation sys-tem over Lake Baikal is also vital for the variation of summerrainfall over North China [8 49] +e anomalous easterlyflow and northerly flow from the anomalous anticyclone areclosely associated with the water vapor flux anomaly overNorth China In Figure 5(b) an anomalous anticycloniccenter of the water vapor flux is also observed over LakeBaikal North China is dominated by the anomalousnortheast water vapor flux+e difference of water vapor fluxover Lake Baikal and North China during two periods issignificant and reaches the 95 confidence level Obviouslythe anomalous northeast water vapor flux from Lake Baikalis beneficial to the interdecadal drought over North China
Mean = 005Trend = 0101Year (98) Mean = minus004
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
(a)
1980 1985 1990 1995 2000 2005 2010 2015ndash5
0
5
UB
UF
(b)
Figure 2 (a)+e time series of ISPNC17 during 1979ndash2016+e horizontal dashed lines indicate the interdecadal mean while solid line from1979 to 1996 indicates the interdecadal trend and the vertical dashed lines indicate the interdecadal shift points (b)+eMann-Kendall testof ISPNC17 (green dotted line shows backward statistic rank series and blue dotted line shows forward statistic rank series) Two black linesshow 95 confidence level
Advances in Meteorology 3
To further investigate which boundary of water vaportransport is critical for interdecadal drought over NorthChina the water vapor transports via four boundaries arecalculated As shown in Figure 6 the anomalous input watervapor transports are via east and north boundary which isconsistent with the fact that North China is dominated bythe northeast flow and northeast water vapor flux in Fig-ure 5 +e interdecadal differences of the water vaportransport via the east boundary and north boundary areinput 914times106 kgs and 2170times106 kgs and the inter-decadal differences of the water vapor transport via the westboundary and south boundary are output 1462times106 kgsand 1847times106 kgs respectively
Because the sum of output water vapor transport isgreater than the sum of input water vapor transport the
difference of water vapor budget over North China isnegative (-225times106 kgs) Numerous studies focused on thefact that weaker summer monsoon flow is responsible forless water vapor transport via south boundary and lesssummer rainfall in North China [34] +is study furtherpoints that water vapor transport via west boundary is alsoimportant for the less summer rainfall in North China +ewater vapor transport via the west boundary is crucial for thesummer rainfall over eastern China [32 33] In the JRA-55data the differences of water vapor transport via fourboundaries of North China have same directions with thosein ERA-Interim data but there is a weak positive differenceof net water vapor budget which is not consistent with theresults in ERA-Interim data +e weak positive difference ofwater vapor budget is against the fact of less rainfall over
0
0
0
0
0
0
0
20
20
20
40
40 60
60
80
ndash100
ndash80
ndash60
ndash60
ndash60
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash20
ndash20
ndash20
ndash20
ndash20
ndash20ndash20
0
0
100degE 105degE 110degE 115degE 120degE 125degE 130degE 135degE30degN
35degN
40degN
45degN
50degN
ndash20
ndash60
ndash40
ndash60
ndash60ndash40
ndash20
20
(a)
30degN
35degN
40degN
45degN
50degN
0
0
0
0
0
0
0
0 0
0
0
0
0
0
0
0
0
0
0
0
0
0
20
20
20
20
20
20
20
20
20
40
40
40
40
40
40
40
40 60
60
60
60
60
80
80100
ndash80
ndash80
ndash60
ndash60
ndash60ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40ndash40
ndash40
ndash40
ndash40ndash40
ndash20
ndash20
ndash20
ndash20
ndash20
ndash20ndash20
ndash20
ndash20
ndash20
ndash20
ndash20 ndash20
ndash20
ndash20
ndash20
ndash20
0
0
0
ndash60
100degE 105degE 110degE 115degE 120degE 125degE 130degE 135degE
(b)
Figure 4 Difference of summer rainfall by 1997ndash2016 mean minus 1979ndash1996 mean for (a) 160 stations and (b) GPCC +e shadingindicates statistically significant difference at the 95 confidence level based on Studentrsquos t-test +e box shows North China
Mean = 016Trend = 0094Year (95) Mean = ndash015
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
(a)
1980 1985 1990 1995 2000 2005 2010 2015ndash4
ndash2
0
2
4
UF
UB
(b)
Figure 3 (a) Same as Figure 2(a) but for the ISPNCGPCC (b) Same as Figure 2(b) but for the ISPNCGPCC
4 Advances in Meteorology
North China +e reason for the weak positive difference ofwater vapor budget over North China in JRA-55 data isworthy of further study
+ere are also obvious interdecadal variations in low andmiddle troposphere As Figure 7(a) shows the anomalouspositive geopotential height at 500 hPa is observed over LakeBaikal +e anomalous positive geopotential height benefitsthe anomalous northerly wind in eastern China +eanomalous positive geopotential height at 500 hPa is asso-ciated with the interdecadal warming over Lake Baikal +einterdecadal warming over Lake Baikal happens not only inthe surface in Figure 7(b) but also in 200 hPa in Figure 8(a)+e interdecadal warming in 200 hPa reduces the meridionalcontrast of air temperature nearby Lake Baikal +ereby thenegative difference of zonal wind exists around 40degN sug-gesting the weakening 200 hPa zonal winds in the inter-decadal time scales As Figure 8(b) shows the northward andwestward movement of the 200 hPa zonal winds center over
the northwest of North China during 1997ndash2016 comparedwith 1979ndash1996 suggests the interdecadal weakening of the200 hPa zonal winds +e strength of the upper-level zonalwinds has great contribution to the precipitation over NorthChina [50 51] +e anomalous descending motion overNorth China in Figure 9 further demonstrates the weakenedpumping role of the 200 hPa zonal winds over North China+e interdecadal weakening of ascending motion andinterdecadal reduction of the water vapor flux over NorthChina result in the interdecadal reduction of precipitationover North China
33e Possible Mechanism of the Interdecadal Variability ofSummer Rainfall over North China +e interdecadalwarming of Lake Baikal has a significant impact on thesummer rainfall over North China [8 48 52] which is alsoconfirmed in Figure 7(b) To discover the abrupt point of the
2170 times 106
1847 times 106
1462 times 106 914 times 106
ERA (1997ndash2016 minus 1979ndash1996)
ndash225 times 106
Unit kgs
(3525Nndash405degN 11025Endash1215degE)
Figure 6 Difference of water vapor budget via each boundary of North China by 1997ndash2016meanminus 1979ndash1996mean (unit kgs) Darkarrows indicate the direction of horizontal water vapor transport difference across each boundary Number in box indicates the difference ofwater vapor budget for North China
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
2
NC
Lake Baikal
(a)
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN60
Lake Baikal
NC
(b)
Figure 5+e difference by 1997ndash2016meanminus 1979ndash1996mean for (a) 850 hPa horizontal winds (units ms) and (b) vertical integral ofwater vapor flux (unit kgms) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test+e red boxshows North China +e green box shows the region of Lake Baikal (40degNndash60degN 80degEndash120degE) +e white region outlines surface pressurelower than 850 hPa
Advances in Meteorology 5
warming of Lake Baikal the standardized time series of theaveraged summer SAT over Lake Baikal (40degNndash60degN80degEndash120degE) is shown in Figure 10(a) +e feature of theinterdecadal and interannual variability of SAT over LakeBaikal is apparent Mann-Kendall test method is used toinvestigate accurate abrupt point of the SATover Lake Baikalin Figure 10(b) +e abrupt year of the SATover Lake Baikalis close to the abrupt year of the summer rainfall over NorthChina
+e SAT over Lake Baikal and the summer rainfall overNorth China have experienced the interdecadal changes
since the mid-1990s +e negative correlation existing be-tween the SATover Lake Baikal and the summer rainfall overNorth China [49] suggests that the interdecadal warming ofLake Baikal contributes to the interdecadal less summerrainfall over North China+e interdecadal warming of LakeBaikal is observed not only in the lower troposphere inFigure 7(b) but also in the upper troposphere in Figure 8(a)+e interdecadal warming of Lake Baikal results in not onlythe anomalous anticyclonic circulation and anomalouspositive geopotential height over Lake Baikal in the lower andmiddle troposphere but also the weakening of the zonal wind
0
0
0
0
0
2
2
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2
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4
4
4
4
44
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6
68
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26
2628
ndash22ndash20
ndash18
ndash1 8
ndash16
ndash 16
ndash14
ndash14
ndash12
ndash12
ndash10
ndash10
ndash8
ndash8
ndash6
ndash6
ndash4
ndash4
ndash4
ndash2
ndash2
ndash2
ndash2
Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
(a)
0202
02
02
02
02
02
02
02
0 2
0202
0202
02
02
02
02
02
02
02
0 2
02
02
02
02
04
04
04
04
04
04
04
04
04
04
04 04 04
04
04
04
04
04
04
04
04
0 4
04
04
04
04 04
06
06
06
06
06
0606
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
08
08
08
08
08
08
08
08
08
08
08
08
08
08
08 08
08
08
08
08
08
1
1
1
1
1
1
1
1
1
1
1
1
11
1
1
1
1
1
1
1
1
12
12
12
12
12
12
14
14
141416
161616
16
1818
18
22
22
ndash06 ndash04
ndash04
ndash04
ndash02
ndash02ndash02
ndash02ndash02
ndash02
ndash02
0
00
0
00
0
0
0
0
00
0
0
0
0
0
0
0
0
0
0
0
0Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
06
02
(b)
Figure 7 Same as Figure 5 but for (a) 500 hPa geopotential height (unit gpm) and (b) SAT (unit degC)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
05
05
05
05
05
05
05
05
05 05 05
0505
1 1
1
1
1
1
1
1
1
1
1 11
115
15
15
15
15 15
15
15
2
2
2
2
2
25
25
25
25
3
3
3
3
35
minus5minus45minus4minus35
minus35
minus3
minus3
minus3
minus3
minus25
minus25
minus25
minus25
minus25
minus2
minus2
2
minus2
minus2
minus2
minus2
minus2
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus1
minus1
minus1 minus1
minus1
minus1
minus1
minus1minus1
minus1
minus1
minus1
minus1
minus05
minus05
minus05minus05
minus05
minus05
minus05
minus05 minus05
minus05
minus05
minus05
minus05
0
minus1 minus08 minus06 minus04 minus02 0 02 04 06 08 1
Lake Baikal
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN minus15
(a)
26
26 3026
30
30
minus30 minus25 minus20 minus15 minus10 minus5 0 5 10 15 20 25 30
Lake Baikal
NC
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
(b)
Figure 8 (a) Same as Figure 5 but for 200 hPa zonal winds (contours unit ms) and temperature (shading unit degC) +e difference oftemperature in blue box with black dots is statistically significant at the 95 confidence level according to Studentrsquos t-test +e difference ofzonal winds with black cross is statistically significant at the 95 confidence level according to Studentrsquos t-test (b) 200 hPa zonal winds (unitms) in JA of 1979ndash1996 mean (black contours) and 1997ndash2016 mean (white contours) +e shading is the climatic mean of 200 hPa zonalwinds during 1979ndash2016 +e black box shows North China +e green box shows the region of Lake Baikal
6 Advances in Meteorology
in the upper troposphere Obviously the anomalous anti-cyclonic circulation over Lake Baikal is beneficial to less watervapor transport from the monsoon flow and the westerliesMeanwhile the weakening of the zonal wind in the uppertroposphere favors the weakening of the ascending motionand further results in the weakening of the pumping effects ofthe zonal winds in the upper troposphere +e interdecadalweakening of the ascending motion and interdecadal re-duction of the water vapor transport to North China directlylead to the interdecadal drought over North China
4 Summary and Discussion
Using the 17-station rainfall and the new GPCC full datamonthly product precipitation data sets the interdecadal
variations of the summer rainfall over North China since themid-1990s are firstly discovered in this paper +e possiblecauses such as the interdecadal variations of the atmosphericcirculation and the water vapor budget are discussed+emajormechanisms are shown in Figure 11 and summarized as follows
Summer rainfall over North China had an increasingtendency during 1979ndash1996 since 1997 this increasingtendency has halted and more summer droughts occurredover North China
+e SAT over Lake Baikal and the summer rainfall overNorth China have had interdecadal abrupt since the mid-1990s +e interdecadal warming of Lake Baikal is beneficialto the interdecadal less summer rainfall over North China
+e intense interdecadal warming of Lake Baikal resultsin not only the anomalous anticyclonic circulation and
20degN 30degN 40degN 50degN 60degN
100
150
200
300
500
700
10000
00 0
0
0
0
0
0
0
0
0 0
0
0
05
05
05
05
05
05
05
05 1
1
1
11
1
1
1
15
1515
15
2 25
335 4
minus2 minus15
minus15
minus15
minus15
minus1
minus1
minus1
minus1
minus1
minus 1
minus1minus05
minus05
minus05
minus05
minus05
minus05
minus05
minusminus05
0Figure 9 Latitude-height cross section of difference of vertical velocity along 11625degE in JA by 1997ndash2016meanminus 1979ndash1996mean (unit10minus 2 Pas) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test +e red line shows North China
Mean = ndash074
Trend = 0069year (96)
Mean = 06
1980 1985 1990 1995 2000 2005 2010 2015
ndash2ndash1012
(a)
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
4
6
UF UB
(b)
Figure 10 (a) Same as Figure 2(a) but for the summer SAT over Lake Baikal (b) Same as Figure 2(b) but for the summer SAT overLake Baikal
Advances in Meteorology 7
anomalous positive geopotential height over Lake Baikal inthe lower and middle troposphere but also the weakening ofthe zonal wind in the upper troposphere +e anomalousanticyclonic circulation in the lower troposphere over LakeBaikal results in less water vapor transport from the mon-soon flow and the westerly flow +e weakening of the zonalwind in the upper troposphere favors the weakening of theascending motion and the pumping effects of the zonalwinds in the upper troposphere+e interdecadal weakeningof the ascending motion and the less interdecadal watervapor transport result in the interdecadal drought in NorthChina
In addition to the contribution of the less water vaportransport from weakened monsoon flow to the summerrainfall over North China the interdecadal reduction of thewater vapor transport from western boundary to NorthChina is also responsible for the halted rainfall tendencyover North China since the mid-1990s which is usuallyignored
+ere are many other factors that also contribute to theinterdecadal variation of the summer rainfall over NorthChina [6] such as Pacific decadal oscillation [52] arcticsea ice [44] and Tibet Plateau snow cover [53] +esefactors and climate model verification are worthy offurther study
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work is supported by the Strategic Priority ResearchProgram of Chinese Academy of Sciences (XDA20100304)the State Key Program of the National Natural ScienceFoundation of China (41475051 41875111) the StartingFoundation of the Civil Aviation University of China(2016QD05X) and the Research Foundation of the CivilAviation University of China (3122015D019)
References
[1] L Han S Li and N Liu ldquoAn approach for improving short-term prediction of summer rainfall over North China bydecomposing interannual and decadal variabilityrdquo Advancesin Atmospheric Sciences vol 31 no 2 pp 435ndash448 2014
[2] Z Yan J Ji and D Ye ldquoNorthern hemispheric summerclimatic jump in the 1960rsquos (I)mdashrainfall and temperaturerdquoScience in China (Series B) vol 33 no 9 pp 1092ndash1101 1990
[3] A Yatagai and T Yasunari ldquoTrends and decadal-scale fluc-tuations of surface air temperature and precipitation overChina and Mongolia during the recent 40 year period (1951-1990)rdquo Journal of the Meteorological Society of Japan Ser IIvol 72 no 6 pp 937ndash957 1994
[4] T Nitta and Z-Z Hu ldquoSummer climate variability in Chinaand its association with 500 hPa height and tropical con-vectionrdquo Journal of theMeteorological Society of Japan vol 74no 4 pp 425ndash445 1996
60degE70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
60deg E70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
20degN
30degN
40degN
50degN
60degN
1997ndash2016 minus 1979ndash1996
850hPa
200hPa
Upper-level jet stream
Lake Baikal
North ChinaDrier
Anomalous anticyclone
Weakened
Anomalousdescendingflows
Figure 11 Schematic diagram of mechanism for the halt of the increasing trend of summer rainfall over North China since the mid-1990s
8 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
+e time series of ISPNCGPCC in Figure 3(a) also showsimilar increasing tendency during 1979ndash1996 with thetrend rate of 0094year which also reaches the 95 con-fidence level according to Studentrsquos t-test +is increasingtendency has also halted since 1997 So the gauge-basedstation precipitation data and the grid precipitation data ofGPCC both show that summer rainfall over North Chinahad an obvious increasing tendency during 1979ndash1996 andhas halted since 1997
To further investigate the interdecadal shift of thesummer rainfall over North China Mann-Kendall testmethod was used to detect the abrupt point of ISPNC17 inFigure 2(b) +ere is a cross point between the backwardstatistic rank series and forward statistic rank series sug-gesting that summer rainfall over North China experienced adistinct interdecadal change around 1996 Since 1997 therehave been more droughts occurring in North China Asevere drought attacking North China in 2014 also indicatedthat North China has become drier in recent years [44]Figure 3(b) further verifies the interdecadal shift of thesummer rainfall over North China using grid precipitationdata of GPCC
+e differences of summer rainfall by 1997ndash2016 meanminus 1979ndash1996 mean over Northeast Asia further verifythe interdecadal variability of summer rainfall over NorthChina in Figure 4 Whether using gauge-based station dataor using the grid precipitation data of GPCC the significantnegative summer rainfall differences are both found overNorth China which is statistically significant at the 95confidence level by Studentrsquos t-test Meanwhile the mainwetter regions are located in the Huaihe River valley whichsuggests that the wetter belt has moved northwards fromsouthern China [45] Meanwhile the spatial pattern of
summer rainfall variation since 1997 has been different fromthe so-called pattern of southern flood and northern droughtsince the end of 1970s [26 27 46 47]
32 e Interdecadal Variability of the AtmosphericCirculation East Asia is dominated by a typical monsoonclimate [45 48] +e summer precipitation change overeastern China affected by the EASM greatly is very sig-nificant on the interannual and interdecadal timescales [10]To further study the causes of drier North China Figure 5(a)shows the difference of the 850 hPa wind during 1997ndash2016with respect to the period of 1979ndash1996 As Figure 5(a)shows North China is dominated by the anomalousnortherly wind from Lake Baikal which suggests that theEASM is weaker in 1997ndash2016 compared with 1979ndash1996Weaker summer monsoon favors the less precipitation overNorth China [12 44]
Meanwhile an anomalous anticyclonic circulationdominates the region of Lake Baikal (40degNndash60degN80degEndash120degE) significantly +e anticyclonic circulation sys-tem over Lake Baikal is also vital for the variation of summerrainfall over North China [8 49] +e anomalous easterlyflow and northerly flow from the anomalous anticyclone areclosely associated with the water vapor flux anomaly overNorth China In Figure 5(b) an anomalous anticycloniccenter of the water vapor flux is also observed over LakeBaikal North China is dominated by the anomalousnortheast water vapor flux+e difference of water vapor fluxover Lake Baikal and North China during two periods issignificant and reaches the 95 confidence level Obviouslythe anomalous northeast water vapor flux from Lake Baikalis beneficial to the interdecadal drought over North China
Mean = 005Trend = 0101Year (98) Mean = minus004
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
(a)
1980 1985 1990 1995 2000 2005 2010 2015ndash5
0
5
UB
UF
(b)
Figure 2 (a)+e time series of ISPNC17 during 1979ndash2016+e horizontal dashed lines indicate the interdecadal mean while solid line from1979 to 1996 indicates the interdecadal trend and the vertical dashed lines indicate the interdecadal shift points (b)+eMann-Kendall testof ISPNC17 (green dotted line shows backward statistic rank series and blue dotted line shows forward statistic rank series) Two black linesshow 95 confidence level
Advances in Meteorology 3
To further investigate which boundary of water vaportransport is critical for interdecadal drought over NorthChina the water vapor transports via four boundaries arecalculated As shown in Figure 6 the anomalous input watervapor transports are via east and north boundary which isconsistent with the fact that North China is dominated bythe northeast flow and northeast water vapor flux in Fig-ure 5 +e interdecadal differences of the water vaportransport via the east boundary and north boundary areinput 914times106 kgs and 2170times106 kgs and the inter-decadal differences of the water vapor transport via the westboundary and south boundary are output 1462times106 kgsand 1847times106 kgs respectively
Because the sum of output water vapor transport isgreater than the sum of input water vapor transport the
difference of water vapor budget over North China isnegative (-225times106 kgs) Numerous studies focused on thefact that weaker summer monsoon flow is responsible forless water vapor transport via south boundary and lesssummer rainfall in North China [34] +is study furtherpoints that water vapor transport via west boundary is alsoimportant for the less summer rainfall in North China +ewater vapor transport via the west boundary is crucial for thesummer rainfall over eastern China [32 33] In the JRA-55data the differences of water vapor transport via fourboundaries of North China have same directions with thosein ERA-Interim data but there is a weak positive differenceof net water vapor budget which is not consistent with theresults in ERA-Interim data +e weak positive difference ofwater vapor budget is against the fact of less rainfall over
0
0
0
0
0
0
0
20
20
20
40
40 60
60
80
ndash100
ndash80
ndash60
ndash60
ndash60
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash20
ndash20
ndash20
ndash20
ndash20
ndash20ndash20
0
0
100degE 105degE 110degE 115degE 120degE 125degE 130degE 135degE30degN
35degN
40degN
45degN
50degN
ndash20
ndash60
ndash40
ndash60
ndash60ndash40
ndash20
20
(a)
30degN
35degN
40degN
45degN
50degN
0
0
0
0
0
0
0
0 0
0
0
0
0
0
0
0
0
0
0
0
0
0
20
20
20
20
20
20
20
20
20
40
40
40
40
40
40
40
40 60
60
60
60
60
80
80100
ndash80
ndash80
ndash60
ndash60
ndash60ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40ndash40
ndash40
ndash40
ndash40ndash40
ndash20
ndash20
ndash20
ndash20
ndash20
ndash20ndash20
ndash20
ndash20
ndash20
ndash20
ndash20 ndash20
ndash20
ndash20
ndash20
ndash20
0
0
0
ndash60
100degE 105degE 110degE 115degE 120degE 125degE 130degE 135degE
(b)
Figure 4 Difference of summer rainfall by 1997ndash2016 mean minus 1979ndash1996 mean for (a) 160 stations and (b) GPCC +e shadingindicates statistically significant difference at the 95 confidence level based on Studentrsquos t-test +e box shows North China
Mean = 016Trend = 0094Year (95) Mean = ndash015
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
(a)
1980 1985 1990 1995 2000 2005 2010 2015ndash4
ndash2
0
2
4
UF
UB
(b)
Figure 3 (a) Same as Figure 2(a) but for the ISPNCGPCC (b) Same as Figure 2(b) but for the ISPNCGPCC
4 Advances in Meteorology
North China +e reason for the weak positive difference ofwater vapor budget over North China in JRA-55 data isworthy of further study
+ere are also obvious interdecadal variations in low andmiddle troposphere As Figure 7(a) shows the anomalouspositive geopotential height at 500 hPa is observed over LakeBaikal +e anomalous positive geopotential height benefitsthe anomalous northerly wind in eastern China +eanomalous positive geopotential height at 500 hPa is asso-ciated with the interdecadal warming over Lake Baikal +einterdecadal warming over Lake Baikal happens not only inthe surface in Figure 7(b) but also in 200 hPa in Figure 8(a)+e interdecadal warming in 200 hPa reduces the meridionalcontrast of air temperature nearby Lake Baikal +ereby thenegative difference of zonal wind exists around 40degN sug-gesting the weakening 200 hPa zonal winds in the inter-decadal time scales As Figure 8(b) shows the northward andwestward movement of the 200 hPa zonal winds center over
the northwest of North China during 1997ndash2016 comparedwith 1979ndash1996 suggests the interdecadal weakening of the200 hPa zonal winds +e strength of the upper-level zonalwinds has great contribution to the precipitation over NorthChina [50 51] +e anomalous descending motion overNorth China in Figure 9 further demonstrates the weakenedpumping role of the 200 hPa zonal winds over North China+e interdecadal weakening of ascending motion andinterdecadal reduction of the water vapor flux over NorthChina result in the interdecadal reduction of precipitationover North China
33e Possible Mechanism of the Interdecadal Variability ofSummer Rainfall over North China +e interdecadalwarming of Lake Baikal has a significant impact on thesummer rainfall over North China [8 48 52] which is alsoconfirmed in Figure 7(b) To discover the abrupt point of the
2170 times 106
1847 times 106
1462 times 106 914 times 106
ERA (1997ndash2016 minus 1979ndash1996)
ndash225 times 106
Unit kgs
(3525Nndash405degN 11025Endash1215degE)
Figure 6 Difference of water vapor budget via each boundary of North China by 1997ndash2016meanminus 1979ndash1996mean (unit kgs) Darkarrows indicate the direction of horizontal water vapor transport difference across each boundary Number in box indicates the difference ofwater vapor budget for North China
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
2
NC
Lake Baikal
(a)
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN60
Lake Baikal
NC
(b)
Figure 5+e difference by 1997ndash2016meanminus 1979ndash1996mean for (a) 850 hPa horizontal winds (units ms) and (b) vertical integral ofwater vapor flux (unit kgms) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test+e red boxshows North China +e green box shows the region of Lake Baikal (40degNndash60degN 80degEndash120degE) +e white region outlines surface pressurelower than 850 hPa
Advances in Meteorology 5
warming of Lake Baikal the standardized time series of theaveraged summer SAT over Lake Baikal (40degNndash60degN80degEndash120degE) is shown in Figure 10(a) +e feature of theinterdecadal and interannual variability of SAT over LakeBaikal is apparent Mann-Kendall test method is used toinvestigate accurate abrupt point of the SATover Lake Baikalin Figure 10(b) +e abrupt year of the SATover Lake Baikalis close to the abrupt year of the summer rainfall over NorthChina
+e SAT over Lake Baikal and the summer rainfall overNorth China have experienced the interdecadal changes
since the mid-1990s +e negative correlation existing be-tween the SATover Lake Baikal and the summer rainfall overNorth China [49] suggests that the interdecadal warming ofLake Baikal contributes to the interdecadal less summerrainfall over North China+e interdecadal warming of LakeBaikal is observed not only in the lower troposphere inFigure 7(b) but also in the upper troposphere in Figure 8(a)+e interdecadal warming of Lake Baikal results in not onlythe anomalous anticyclonic circulation and anomalouspositive geopotential height over Lake Baikal in the lower andmiddle troposphere but also the weakening of the zonal wind
0
0
0
0
0
2
2
2
2
2
2
2
2
4
4
4
4
4
4
44
4
4
4
6
6
6
6
6
66
6
68
8
8
8
8
8
8
8
10
10
10
10
10
10
10
10
12
12
12
12
12
12 1214
14
1414
14
14
14
1616
1616
16
16
1818
1818
18
18
20
20
20
20
20
20
22
22
22
24
24
24
26
2628
ndash22ndash20
ndash18
ndash1 8
ndash16
ndash 16
ndash14
ndash14
ndash12
ndash12
ndash10
ndash10
ndash8
ndash8
ndash6
ndash6
ndash4
ndash4
ndash4
ndash2
ndash2
ndash2
ndash2
Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
(a)
0202
02
02
02
02
02
02
02
0 2
0202
0202
02
02
02
02
02
02
02
0 2
02
02
02
02
04
04
04
04
04
04
04
04
04
04
04 04 04
04
04
04
04
04
04
04
04
0 4
04
04
04
04 04
06
06
06
06
06
0606
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
08
08
08
08
08
08
08
08
08
08
08
08
08
08
08 08
08
08
08
08
08
1
1
1
1
1
1
1
1
1
1
1
1
11
1
1
1
1
1
1
1
1
12
12
12
12
12
12
14
14
141416
161616
16
1818
18
22
22
ndash06 ndash04
ndash04
ndash04
ndash02
ndash02ndash02
ndash02ndash02
ndash02
ndash02
0
00
0
00
0
0
0
0
00
0
0
0
0
0
0
0
0
0
0
0
0Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
06
02
(b)
Figure 7 Same as Figure 5 but for (a) 500 hPa geopotential height (unit gpm) and (b) SAT (unit degC)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
05
05
05
05
05
05
05
05
05 05 05
0505
1 1
1
1
1
1
1
1
1
1
1 11
115
15
15
15
15 15
15
15
2
2
2
2
2
25
25
25
25
3
3
3
3
35
minus5minus45minus4minus35
minus35
minus3
minus3
minus3
minus3
minus25
minus25
minus25
minus25
minus25
minus2
minus2
2
minus2
minus2
minus2
minus2
minus2
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus1
minus1
minus1 minus1
minus1
minus1
minus1
minus1minus1
minus1
minus1
minus1
minus1
minus05
minus05
minus05minus05
minus05
minus05
minus05
minus05 minus05
minus05
minus05
minus05
minus05
0
minus1 minus08 minus06 minus04 minus02 0 02 04 06 08 1
Lake Baikal
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN minus15
(a)
26
26 3026
30
30
minus30 minus25 minus20 minus15 minus10 minus5 0 5 10 15 20 25 30
Lake Baikal
NC
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
(b)
Figure 8 (a) Same as Figure 5 but for 200 hPa zonal winds (contours unit ms) and temperature (shading unit degC) +e difference oftemperature in blue box with black dots is statistically significant at the 95 confidence level according to Studentrsquos t-test +e difference ofzonal winds with black cross is statistically significant at the 95 confidence level according to Studentrsquos t-test (b) 200 hPa zonal winds (unitms) in JA of 1979ndash1996 mean (black contours) and 1997ndash2016 mean (white contours) +e shading is the climatic mean of 200 hPa zonalwinds during 1979ndash2016 +e black box shows North China +e green box shows the region of Lake Baikal
6 Advances in Meteorology
in the upper troposphere Obviously the anomalous anti-cyclonic circulation over Lake Baikal is beneficial to less watervapor transport from the monsoon flow and the westerliesMeanwhile the weakening of the zonal wind in the uppertroposphere favors the weakening of the ascending motionand further results in the weakening of the pumping effects ofthe zonal winds in the upper troposphere +e interdecadalweakening of the ascending motion and interdecadal re-duction of the water vapor transport to North China directlylead to the interdecadal drought over North China
4 Summary and Discussion
Using the 17-station rainfall and the new GPCC full datamonthly product precipitation data sets the interdecadal
variations of the summer rainfall over North China since themid-1990s are firstly discovered in this paper +e possiblecauses such as the interdecadal variations of the atmosphericcirculation and the water vapor budget are discussed+emajormechanisms are shown in Figure 11 and summarized as follows
Summer rainfall over North China had an increasingtendency during 1979ndash1996 since 1997 this increasingtendency has halted and more summer droughts occurredover North China
+e SAT over Lake Baikal and the summer rainfall overNorth China have had interdecadal abrupt since the mid-1990s +e interdecadal warming of Lake Baikal is beneficialto the interdecadal less summer rainfall over North China
+e intense interdecadal warming of Lake Baikal resultsin not only the anomalous anticyclonic circulation and
20degN 30degN 40degN 50degN 60degN
100
150
200
300
500
700
10000
00 0
0
0
0
0
0
0
0
0 0
0
0
05
05
05
05
05
05
05
05 1
1
1
11
1
1
1
15
1515
15
2 25
335 4
minus2 minus15
minus15
minus15
minus15
minus1
minus1
minus1
minus1
minus1
minus 1
minus1minus05
minus05
minus05
minus05
minus05
minus05
minus05
minusminus05
0Figure 9 Latitude-height cross section of difference of vertical velocity along 11625degE in JA by 1997ndash2016meanminus 1979ndash1996mean (unit10minus 2 Pas) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test +e red line shows North China
Mean = ndash074
Trend = 0069year (96)
Mean = 06
1980 1985 1990 1995 2000 2005 2010 2015
ndash2ndash1012
(a)
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
4
6
UF UB
(b)
Figure 10 (a) Same as Figure 2(a) but for the summer SAT over Lake Baikal (b) Same as Figure 2(b) but for the summer SAT overLake Baikal
Advances in Meteorology 7
anomalous positive geopotential height over Lake Baikal inthe lower and middle troposphere but also the weakening ofthe zonal wind in the upper troposphere +e anomalousanticyclonic circulation in the lower troposphere over LakeBaikal results in less water vapor transport from the mon-soon flow and the westerly flow +e weakening of the zonalwind in the upper troposphere favors the weakening of theascending motion and the pumping effects of the zonalwinds in the upper troposphere+e interdecadal weakeningof the ascending motion and the less interdecadal watervapor transport result in the interdecadal drought in NorthChina
In addition to the contribution of the less water vaportransport from weakened monsoon flow to the summerrainfall over North China the interdecadal reduction of thewater vapor transport from western boundary to NorthChina is also responsible for the halted rainfall tendencyover North China since the mid-1990s which is usuallyignored
+ere are many other factors that also contribute to theinterdecadal variation of the summer rainfall over NorthChina [6] such as Pacific decadal oscillation [52] arcticsea ice [44] and Tibet Plateau snow cover [53] +esefactors and climate model verification are worthy offurther study
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work is supported by the Strategic Priority ResearchProgram of Chinese Academy of Sciences (XDA20100304)the State Key Program of the National Natural ScienceFoundation of China (41475051 41875111) the StartingFoundation of the Civil Aviation University of China(2016QD05X) and the Research Foundation of the CivilAviation University of China (3122015D019)
References
[1] L Han S Li and N Liu ldquoAn approach for improving short-term prediction of summer rainfall over North China bydecomposing interannual and decadal variabilityrdquo Advancesin Atmospheric Sciences vol 31 no 2 pp 435ndash448 2014
[2] Z Yan J Ji and D Ye ldquoNorthern hemispheric summerclimatic jump in the 1960rsquos (I)mdashrainfall and temperaturerdquoScience in China (Series B) vol 33 no 9 pp 1092ndash1101 1990
[3] A Yatagai and T Yasunari ldquoTrends and decadal-scale fluc-tuations of surface air temperature and precipitation overChina and Mongolia during the recent 40 year period (1951-1990)rdquo Journal of the Meteorological Society of Japan Ser IIvol 72 no 6 pp 937ndash957 1994
[4] T Nitta and Z-Z Hu ldquoSummer climate variability in Chinaand its association with 500 hPa height and tropical con-vectionrdquo Journal of theMeteorological Society of Japan vol 74no 4 pp 425ndash445 1996
60degE70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
60deg E70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
20degN
30degN
40degN
50degN
60degN
1997ndash2016 minus 1979ndash1996
850hPa
200hPa
Upper-level jet stream
Lake Baikal
North ChinaDrier
Anomalous anticyclone
Weakened
Anomalousdescendingflows
Figure 11 Schematic diagram of mechanism for the halt of the increasing trend of summer rainfall over North China since the mid-1990s
8 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
To further investigate which boundary of water vaportransport is critical for interdecadal drought over NorthChina the water vapor transports via four boundaries arecalculated As shown in Figure 6 the anomalous input watervapor transports are via east and north boundary which isconsistent with the fact that North China is dominated bythe northeast flow and northeast water vapor flux in Fig-ure 5 +e interdecadal differences of the water vaportransport via the east boundary and north boundary areinput 914times106 kgs and 2170times106 kgs and the inter-decadal differences of the water vapor transport via the westboundary and south boundary are output 1462times106 kgsand 1847times106 kgs respectively
Because the sum of output water vapor transport isgreater than the sum of input water vapor transport the
difference of water vapor budget over North China isnegative (-225times106 kgs) Numerous studies focused on thefact that weaker summer monsoon flow is responsible forless water vapor transport via south boundary and lesssummer rainfall in North China [34] +is study furtherpoints that water vapor transport via west boundary is alsoimportant for the less summer rainfall in North China +ewater vapor transport via the west boundary is crucial for thesummer rainfall over eastern China [32 33] In the JRA-55data the differences of water vapor transport via fourboundaries of North China have same directions with thosein ERA-Interim data but there is a weak positive differenceof net water vapor budget which is not consistent with theresults in ERA-Interim data +e weak positive difference ofwater vapor budget is against the fact of less rainfall over
0
0
0
0
0
0
0
20
20
20
40
40 60
60
80
ndash100
ndash80
ndash60
ndash60
ndash60
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash20
ndash20
ndash20
ndash20
ndash20
ndash20ndash20
0
0
100degE 105degE 110degE 115degE 120degE 125degE 130degE 135degE30degN
35degN
40degN
45degN
50degN
ndash20
ndash60
ndash40
ndash60
ndash60ndash40
ndash20
20
(a)
30degN
35degN
40degN
45degN
50degN
0
0
0
0
0
0
0
0 0
0
0
0
0
0
0
0
0
0
0
0
0
0
20
20
20
20
20
20
20
20
20
40
40
40
40
40
40
40
40 60
60
60
60
60
80
80100
ndash80
ndash80
ndash60
ndash60
ndash60ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40
ndash40ndash40
ndash40
ndash40
ndash40ndash40
ndash20
ndash20
ndash20
ndash20
ndash20
ndash20ndash20
ndash20
ndash20
ndash20
ndash20
ndash20 ndash20
ndash20
ndash20
ndash20
ndash20
0
0
0
ndash60
100degE 105degE 110degE 115degE 120degE 125degE 130degE 135degE
(b)
Figure 4 Difference of summer rainfall by 1997ndash2016 mean minus 1979ndash1996 mean for (a) 160 stations and (b) GPCC +e shadingindicates statistically significant difference at the 95 confidence level based on Studentrsquos t-test +e box shows North China
Mean = 016Trend = 0094Year (95) Mean = ndash015
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
(a)
1980 1985 1990 1995 2000 2005 2010 2015ndash4
ndash2
0
2
4
UF
UB
(b)
Figure 3 (a) Same as Figure 2(a) but for the ISPNCGPCC (b) Same as Figure 2(b) but for the ISPNCGPCC
4 Advances in Meteorology
North China +e reason for the weak positive difference ofwater vapor budget over North China in JRA-55 data isworthy of further study
+ere are also obvious interdecadal variations in low andmiddle troposphere As Figure 7(a) shows the anomalouspositive geopotential height at 500 hPa is observed over LakeBaikal +e anomalous positive geopotential height benefitsthe anomalous northerly wind in eastern China +eanomalous positive geopotential height at 500 hPa is asso-ciated with the interdecadal warming over Lake Baikal +einterdecadal warming over Lake Baikal happens not only inthe surface in Figure 7(b) but also in 200 hPa in Figure 8(a)+e interdecadal warming in 200 hPa reduces the meridionalcontrast of air temperature nearby Lake Baikal +ereby thenegative difference of zonal wind exists around 40degN sug-gesting the weakening 200 hPa zonal winds in the inter-decadal time scales As Figure 8(b) shows the northward andwestward movement of the 200 hPa zonal winds center over
the northwest of North China during 1997ndash2016 comparedwith 1979ndash1996 suggests the interdecadal weakening of the200 hPa zonal winds +e strength of the upper-level zonalwinds has great contribution to the precipitation over NorthChina [50 51] +e anomalous descending motion overNorth China in Figure 9 further demonstrates the weakenedpumping role of the 200 hPa zonal winds over North China+e interdecadal weakening of ascending motion andinterdecadal reduction of the water vapor flux over NorthChina result in the interdecadal reduction of precipitationover North China
33e Possible Mechanism of the Interdecadal Variability ofSummer Rainfall over North China +e interdecadalwarming of Lake Baikal has a significant impact on thesummer rainfall over North China [8 48 52] which is alsoconfirmed in Figure 7(b) To discover the abrupt point of the
2170 times 106
1847 times 106
1462 times 106 914 times 106
ERA (1997ndash2016 minus 1979ndash1996)
ndash225 times 106
Unit kgs
(3525Nndash405degN 11025Endash1215degE)
Figure 6 Difference of water vapor budget via each boundary of North China by 1997ndash2016meanminus 1979ndash1996mean (unit kgs) Darkarrows indicate the direction of horizontal water vapor transport difference across each boundary Number in box indicates the difference ofwater vapor budget for North China
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
2
NC
Lake Baikal
(a)
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN60
Lake Baikal
NC
(b)
Figure 5+e difference by 1997ndash2016meanminus 1979ndash1996mean for (a) 850 hPa horizontal winds (units ms) and (b) vertical integral ofwater vapor flux (unit kgms) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test+e red boxshows North China +e green box shows the region of Lake Baikal (40degNndash60degN 80degEndash120degE) +e white region outlines surface pressurelower than 850 hPa
Advances in Meteorology 5
warming of Lake Baikal the standardized time series of theaveraged summer SAT over Lake Baikal (40degNndash60degN80degEndash120degE) is shown in Figure 10(a) +e feature of theinterdecadal and interannual variability of SAT over LakeBaikal is apparent Mann-Kendall test method is used toinvestigate accurate abrupt point of the SATover Lake Baikalin Figure 10(b) +e abrupt year of the SATover Lake Baikalis close to the abrupt year of the summer rainfall over NorthChina
+e SAT over Lake Baikal and the summer rainfall overNorth China have experienced the interdecadal changes
since the mid-1990s +e negative correlation existing be-tween the SATover Lake Baikal and the summer rainfall overNorth China [49] suggests that the interdecadal warming ofLake Baikal contributes to the interdecadal less summerrainfall over North China+e interdecadal warming of LakeBaikal is observed not only in the lower troposphere inFigure 7(b) but also in the upper troposphere in Figure 8(a)+e interdecadal warming of Lake Baikal results in not onlythe anomalous anticyclonic circulation and anomalouspositive geopotential height over Lake Baikal in the lower andmiddle troposphere but also the weakening of the zonal wind
0
0
0
0
0
2
2
2
2
2
2
2
2
4
4
4
4
4
4
44
4
4
4
6
6
6
6
6
66
6
68
8
8
8
8
8
8
8
10
10
10
10
10
10
10
10
12
12
12
12
12
12 1214
14
1414
14
14
14
1616
1616
16
16
1818
1818
18
18
20
20
20
20
20
20
22
22
22
24
24
24
26
2628
ndash22ndash20
ndash18
ndash1 8
ndash16
ndash 16
ndash14
ndash14
ndash12
ndash12
ndash10
ndash10
ndash8
ndash8
ndash6
ndash6
ndash4
ndash4
ndash4
ndash2
ndash2
ndash2
ndash2
Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
(a)
0202
02
02
02
02
02
02
02
0 2
0202
0202
02
02
02
02
02
02
02
0 2
02
02
02
02
04
04
04
04
04
04
04
04
04
04
04 04 04
04
04
04
04
04
04
04
04
0 4
04
04
04
04 04
06
06
06
06
06
0606
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
08
08
08
08
08
08
08
08
08
08
08
08
08
08
08 08
08
08
08
08
08
1
1
1
1
1
1
1
1
1
1
1
1
11
1
1
1
1
1
1
1
1
12
12
12
12
12
12
14
14
141416
161616
16
1818
18
22
22
ndash06 ndash04
ndash04
ndash04
ndash02
ndash02ndash02
ndash02ndash02
ndash02
ndash02
0
00
0
00
0
0
0
0
00
0
0
0
0
0
0
0
0
0
0
0
0Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
06
02
(b)
Figure 7 Same as Figure 5 but for (a) 500 hPa geopotential height (unit gpm) and (b) SAT (unit degC)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
05
05
05
05
05
05
05
05
05 05 05
0505
1 1
1
1
1
1
1
1
1
1
1 11
115
15
15
15
15 15
15
15
2
2
2
2
2
25
25
25
25
3
3
3
3
35
minus5minus45minus4minus35
minus35
minus3
minus3
minus3
minus3
minus25
minus25
minus25
minus25
minus25
minus2
minus2
2
minus2
minus2
minus2
minus2
minus2
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus1
minus1
minus1 minus1
minus1
minus1
minus1
minus1minus1
minus1
minus1
minus1
minus1
minus05
minus05
minus05minus05
minus05
minus05
minus05
minus05 minus05
minus05
minus05
minus05
minus05
0
minus1 minus08 minus06 minus04 minus02 0 02 04 06 08 1
Lake Baikal
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN minus15
(a)
26
26 3026
30
30
minus30 minus25 minus20 minus15 minus10 minus5 0 5 10 15 20 25 30
Lake Baikal
NC
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
(b)
Figure 8 (a) Same as Figure 5 but for 200 hPa zonal winds (contours unit ms) and temperature (shading unit degC) +e difference oftemperature in blue box with black dots is statistically significant at the 95 confidence level according to Studentrsquos t-test +e difference ofzonal winds with black cross is statistically significant at the 95 confidence level according to Studentrsquos t-test (b) 200 hPa zonal winds (unitms) in JA of 1979ndash1996 mean (black contours) and 1997ndash2016 mean (white contours) +e shading is the climatic mean of 200 hPa zonalwinds during 1979ndash2016 +e black box shows North China +e green box shows the region of Lake Baikal
6 Advances in Meteorology
in the upper troposphere Obviously the anomalous anti-cyclonic circulation over Lake Baikal is beneficial to less watervapor transport from the monsoon flow and the westerliesMeanwhile the weakening of the zonal wind in the uppertroposphere favors the weakening of the ascending motionand further results in the weakening of the pumping effects ofthe zonal winds in the upper troposphere +e interdecadalweakening of the ascending motion and interdecadal re-duction of the water vapor transport to North China directlylead to the interdecadal drought over North China
4 Summary and Discussion
Using the 17-station rainfall and the new GPCC full datamonthly product precipitation data sets the interdecadal
variations of the summer rainfall over North China since themid-1990s are firstly discovered in this paper +e possiblecauses such as the interdecadal variations of the atmosphericcirculation and the water vapor budget are discussed+emajormechanisms are shown in Figure 11 and summarized as follows
Summer rainfall over North China had an increasingtendency during 1979ndash1996 since 1997 this increasingtendency has halted and more summer droughts occurredover North China
+e SAT over Lake Baikal and the summer rainfall overNorth China have had interdecadal abrupt since the mid-1990s +e interdecadal warming of Lake Baikal is beneficialto the interdecadal less summer rainfall over North China
+e intense interdecadal warming of Lake Baikal resultsin not only the anomalous anticyclonic circulation and
20degN 30degN 40degN 50degN 60degN
100
150
200
300
500
700
10000
00 0
0
0
0
0
0
0
0
0 0
0
0
05
05
05
05
05
05
05
05 1
1
1
11
1
1
1
15
1515
15
2 25
335 4
minus2 minus15
minus15
minus15
minus15
minus1
minus1
minus1
minus1
minus1
minus 1
minus1minus05
minus05
minus05
minus05
minus05
minus05
minus05
minusminus05
0Figure 9 Latitude-height cross section of difference of vertical velocity along 11625degE in JA by 1997ndash2016meanminus 1979ndash1996mean (unit10minus 2 Pas) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test +e red line shows North China
Mean = ndash074
Trend = 0069year (96)
Mean = 06
1980 1985 1990 1995 2000 2005 2010 2015
ndash2ndash1012
(a)
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
4
6
UF UB
(b)
Figure 10 (a) Same as Figure 2(a) but for the summer SAT over Lake Baikal (b) Same as Figure 2(b) but for the summer SAT overLake Baikal
Advances in Meteorology 7
anomalous positive geopotential height over Lake Baikal inthe lower and middle troposphere but also the weakening ofthe zonal wind in the upper troposphere +e anomalousanticyclonic circulation in the lower troposphere over LakeBaikal results in less water vapor transport from the mon-soon flow and the westerly flow +e weakening of the zonalwind in the upper troposphere favors the weakening of theascending motion and the pumping effects of the zonalwinds in the upper troposphere+e interdecadal weakeningof the ascending motion and the less interdecadal watervapor transport result in the interdecadal drought in NorthChina
In addition to the contribution of the less water vaportransport from weakened monsoon flow to the summerrainfall over North China the interdecadal reduction of thewater vapor transport from western boundary to NorthChina is also responsible for the halted rainfall tendencyover North China since the mid-1990s which is usuallyignored
+ere are many other factors that also contribute to theinterdecadal variation of the summer rainfall over NorthChina [6] such as Pacific decadal oscillation [52] arcticsea ice [44] and Tibet Plateau snow cover [53] +esefactors and climate model verification are worthy offurther study
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work is supported by the Strategic Priority ResearchProgram of Chinese Academy of Sciences (XDA20100304)the State Key Program of the National Natural ScienceFoundation of China (41475051 41875111) the StartingFoundation of the Civil Aviation University of China(2016QD05X) and the Research Foundation of the CivilAviation University of China (3122015D019)
References
[1] L Han S Li and N Liu ldquoAn approach for improving short-term prediction of summer rainfall over North China bydecomposing interannual and decadal variabilityrdquo Advancesin Atmospheric Sciences vol 31 no 2 pp 435ndash448 2014
[2] Z Yan J Ji and D Ye ldquoNorthern hemispheric summerclimatic jump in the 1960rsquos (I)mdashrainfall and temperaturerdquoScience in China (Series B) vol 33 no 9 pp 1092ndash1101 1990
[3] A Yatagai and T Yasunari ldquoTrends and decadal-scale fluc-tuations of surface air temperature and precipitation overChina and Mongolia during the recent 40 year period (1951-1990)rdquo Journal of the Meteorological Society of Japan Ser IIvol 72 no 6 pp 937ndash957 1994
[4] T Nitta and Z-Z Hu ldquoSummer climate variability in Chinaand its association with 500 hPa height and tropical con-vectionrdquo Journal of theMeteorological Society of Japan vol 74no 4 pp 425ndash445 1996
60degE70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
60deg E70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
20degN
30degN
40degN
50degN
60degN
1997ndash2016 minus 1979ndash1996
850hPa
200hPa
Upper-level jet stream
Lake Baikal
North ChinaDrier
Anomalous anticyclone
Weakened
Anomalousdescendingflows
Figure 11 Schematic diagram of mechanism for the halt of the increasing trend of summer rainfall over North China since the mid-1990s
8 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
North China +e reason for the weak positive difference ofwater vapor budget over North China in JRA-55 data isworthy of further study
+ere are also obvious interdecadal variations in low andmiddle troposphere As Figure 7(a) shows the anomalouspositive geopotential height at 500 hPa is observed over LakeBaikal +e anomalous positive geopotential height benefitsthe anomalous northerly wind in eastern China +eanomalous positive geopotential height at 500 hPa is asso-ciated with the interdecadal warming over Lake Baikal +einterdecadal warming over Lake Baikal happens not only inthe surface in Figure 7(b) but also in 200 hPa in Figure 8(a)+e interdecadal warming in 200 hPa reduces the meridionalcontrast of air temperature nearby Lake Baikal +ereby thenegative difference of zonal wind exists around 40degN sug-gesting the weakening 200 hPa zonal winds in the inter-decadal time scales As Figure 8(b) shows the northward andwestward movement of the 200 hPa zonal winds center over
the northwest of North China during 1997ndash2016 comparedwith 1979ndash1996 suggests the interdecadal weakening of the200 hPa zonal winds +e strength of the upper-level zonalwinds has great contribution to the precipitation over NorthChina [50 51] +e anomalous descending motion overNorth China in Figure 9 further demonstrates the weakenedpumping role of the 200 hPa zonal winds over North China+e interdecadal weakening of ascending motion andinterdecadal reduction of the water vapor flux over NorthChina result in the interdecadal reduction of precipitationover North China
33e Possible Mechanism of the Interdecadal Variability ofSummer Rainfall over North China +e interdecadalwarming of Lake Baikal has a significant impact on thesummer rainfall over North China [8 48 52] which is alsoconfirmed in Figure 7(b) To discover the abrupt point of the
2170 times 106
1847 times 106
1462 times 106 914 times 106
ERA (1997ndash2016 minus 1979ndash1996)
ndash225 times 106
Unit kgs
(3525Nndash405degN 11025Endash1215degE)
Figure 6 Difference of water vapor budget via each boundary of North China by 1997ndash2016meanminus 1979ndash1996mean (unit kgs) Darkarrows indicate the direction of horizontal water vapor transport difference across each boundary Number in box indicates the difference ofwater vapor budget for North China
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
2
NC
Lake Baikal
(a)
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN60
Lake Baikal
NC
(b)
Figure 5+e difference by 1997ndash2016meanminus 1979ndash1996mean for (a) 850 hPa horizontal winds (units ms) and (b) vertical integral ofwater vapor flux (unit kgms) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test+e red boxshows North China +e green box shows the region of Lake Baikal (40degNndash60degN 80degEndash120degE) +e white region outlines surface pressurelower than 850 hPa
Advances in Meteorology 5
warming of Lake Baikal the standardized time series of theaveraged summer SAT over Lake Baikal (40degNndash60degN80degEndash120degE) is shown in Figure 10(a) +e feature of theinterdecadal and interannual variability of SAT over LakeBaikal is apparent Mann-Kendall test method is used toinvestigate accurate abrupt point of the SATover Lake Baikalin Figure 10(b) +e abrupt year of the SATover Lake Baikalis close to the abrupt year of the summer rainfall over NorthChina
+e SAT over Lake Baikal and the summer rainfall overNorth China have experienced the interdecadal changes
since the mid-1990s +e negative correlation existing be-tween the SATover Lake Baikal and the summer rainfall overNorth China [49] suggests that the interdecadal warming ofLake Baikal contributes to the interdecadal less summerrainfall over North China+e interdecadal warming of LakeBaikal is observed not only in the lower troposphere inFigure 7(b) but also in the upper troposphere in Figure 8(a)+e interdecadal warming of Lake Baikal results in not onlythe anomalous anticyclonic circulation and anomalouspositive geopotential height over Lake Baikal in the lower andmiddle troposphere but also the weakening of the zonal wind
0
0
0
0
0
2
2
2
2
2
2
2
2
4
4
4
4
4
4
44
4
4
4
6
6
6
6
6
66
6
68
8
8
8
8
8
8
8
10
10
10
10
10
10
10
10
12
12
12
12
12
12 1214
14
1414
14
14
14
1616
1616
16
16
1818
1818
18
18
20
20
20
20
20
20
22
22
22
24
24
24
26
2628
ndash22ndash20
ndash18
ndash1 8
ndash16
ndash 16
ndash14
ndash14
ndash12
ndash12
ndash10
ndash10
ndash8
ndash8
ndash6
ndash6
ndash4
ndash4
ndash4
ndash2
ndash2
ndash2
ndash2
Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
(a)
0202
02
02
02
02
02
02
02
0 2
0202
0202
02
02
02
02
02
02
02
0 2
02
02
02
02
04
04
04
04
04
04
04
04
04
04
04 04 04
04
04
04
04
04
04
04
04
0 4
04
04
04
04 04
06
06
06
06
06
0606
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
08
08
08
08
08
08
08
08
08
08
08
08
08
08
08 08
08
08
08
08
08
1
1
1
1
1
1
1
1
1
1
1
1
11
1
1
1
1
1
1
1
1
12
12
12
12
12
12
14
14
141416
161616
16
1818
18
22
22
ndash06 ndash04
ndash04
ndash04
ndash02
ndash02ndash02
ndash02ndash02
ndash02
ndash02
0
00
0
00
0
0
0
0
00
0
0
0
0
0
0
0
0
0
0
0
0Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
06
02
(b)
Figure 7 Same as Figure 5 but for (a) 500 hPa geopotential height (unit gpm) and (b) SAT (unit degC)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
05
05
05
05
05
05
05
05
05 05 05
0505
1 1
1
1
1
1
1
1
1
1
1 11
115
15
15
15
15 15
15
15
2
2
2
2
2
25
25
25
25
3
3
3
3
35
minus5minus45minus4minus35
minus35
minus3
minus3
minus3
minus3
minus25
minus25
minus25
minus25
minus25
minus2
minus2
2
minus2
minus2
minus2
minus2
minus2
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus1
minus1
minus1 minus1
minus1
minus1
minus1
minus1minus1
minus1
minus1
minus1
minus1
minus05
minus05
minus05minus05
minus05
minus05
minus05
minus05 minus05
minus05
minus05
minus05
minus05
0
minus1 minus08 minus06 minus04 minus02 0 02 04 06 08 1
Lake Baikal
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN minus15
(a)
26
26 3026
30
30
minus30 minus25 minus20 minus15 minus10 minus5 0 5 10 15 20 25 30
Lake Baikal
NC
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
(b)
Figure 8 (a) Same as Figure 5 but for 200 hPa zonal winds (contours unit ms) and temperature (shading unit degC) +e difference oftemperature in blue box with black dots is statistically significant at the 95 confidence level according to Studentrsquos t-test +e difference ofzonal winds with black cross is statistically significant at the 95 confidence level according to Studentrsquos t-test (b) 200 hPa zonal winds (unitms) in JA of 1979ndash1996 mean (black contours) and 1997ndash2016 mean (white contours) +e shading is the climatic mean of 200 hPa zonalwinds during 1979ndash2016 +e black box shows North China +e green box shows the region of Lake Baikal
6 Advances in Meteorology
in the upper troposphere Obviously the anomalous anti-cyclonic circulation over Lake Baikal is beneficial to less watervapor transport from the monsoon flow and the westerliesMeanwhile the weakening of the zonal wind in the uppertroposphere favors the weakening of the ascending motionand further results in the weakening of the pumping effects ofthe zonal winds in the upper troposphere +e interdecadalweakening of the ascending motion and interdecadal re-duction of the water vapor transport to North China directlylead to the interdecadal drought over North China
4 Summary and Discussion
Using the 17-station rainfall and the new GPCC full datamonthly product precipitation data sets the interdecadal
variations of the summer rainfall over North China since themid-1990s are firstly discovered in this paper +e possiblecauses such as the interdecadal variations of the atmosphericcirculation and the water vapor budget are discussed+emajormechanisms are shown in Figure 11 and summarized as follows
Summer rainfall over North China had an increasingtendency during 1979ndash1996 since 1997 this increasingtendency has halted and more summer droughts occurredover North China
+e SAT over Lake Baikal and the summer rainfall overNorth China have had interdecadal abrupt since the mid-1990s +e interdecadal warming of Lake Baikal is beneficialto the interdecadal less summer rainfall over North China
+e intense interdecadal warming of Lake Baikal resultsin not only the anomalous anticyclonic circulation and
20degN 30degN 40degN 50degN 60degN
100
150
200
300
500
700
10000
00 0
0
0
0
0
0
0
0
0 0
0
0
05
05
05
05
05
05
05
05 1
1
1
11
1
1
1
15
1515
15
2 25
335 4
minus2 minus15
minus15
minus15
minus15
minus1
minus1
minus1
minus1
minus1
minus 1
minus1minus05
minus05
minus05
minus05
minus05
minus05
minus05
minusminus05
0Figure 9 Latitude-height cross section of difference of vertical velocity along 11625degE in JA by 1997ndash2016meanminus 1979ndash1996mean (unit10minus 2 Pas) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test +e red line shows North China
Mean = ndash074
Trend = 0069year (96)
Mean = 06
1980 1985 1990 1995 2000 2005 2010 2015
ndash2ndash1012
(a)
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
4
6
UF UB
(b)
Figure 10 (a) Same as Figure 2(a) but for the summer SAT over Lake Baikal (b) Same as Figure 2(b) but for the summer SAT overLake Baikal
Advances in Meteorology 7
anomalous positive geopotential height over Lake Baikal inthe lower and middle troposphere but also the weakening ofthe zonal wind in the upper troposphere +e anomalousanticyclonic circulation in the lower troposphere over LakeBaikal results in less water vapor transport from the mon-soon flow and the westerly flow +e weakening of the zonalwind in the upper troposphere favors the weakening of theascending motion and the pumping effects of the zonalwinds in the upper troposphere+e interdecadal weakeningof the ascending motion and the less interdecadal watervapor transport result in the interdecadal drought in NorthChina
In addition to the contribution of the less water vaportransport from weakened monsoon flow to the summerrainfall over North China the interdecadal reduction of thewater vapor transport from western boundary to NorthChina is also responsible for the halted rainfall tendencyover North China since the mid-1990s which is usuallyignored
+ere are many other factors that also contribute to theinterdecadal variation of the summer rainfall over NorthChina [6] such as Pacific decadal oscillation [52] arcticsea ice [44] and Tibet Plateau snow cover [53] +esefactors and climate model verification are worthy offurther study
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work is supported by the Strategic Priority ResearchProgram of Chinese Academy of Sciences (XDA20100304)the State Key Program of the National Natural ScienceFoundation of China (41475051 41875111) the StartingFoundation of the Civil Aviation University of China(2016QD05X) and the Research Foundation of the CivilAviation University of China (3122015D019)
References
[1] L Han S Li and N Liu ldquoAn approach for improving short-term prediction of summer rainfall over North China bydecomposing interannual and decadal variabilityrdquo Advancesin Atmospheric Sciences vol 31 no 2 pp 435ndash448 2014
[2] Z Yan J Ji and D Ye ldquoNorthern hemispheric summerclimatic jump in the 1960rsquos (I)mdashrainfall and temperaturerdquoScience in China (Series B) vol 33 no 9 pp 1092ndash1101 1990
[3] A Yatagai and T Yasunari ldquoTrends and decadal-scale fluc-tuations of surface air temperature and precipitation overChina and Mongolia during the recent 40 year period (1951-1990)rdquo Journal of the Meteorological Society of Japan Ser IIvol 72 no 6 pp 937ndash957 1994
[4] T Nitta and Z-Z Hu ldquoSummer climate variability in Chinaand its association with 500 hPa height and tropical con-vectionrdquo Journal of theMeteorological Society of Japan vol 74no 4 pp 425ndash445 1996
60degE70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
60deg E70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
20degN
30degN
40degN
50degN
60degN
1997ndash2016 minus 1979ndash1996
850hPa
200hPa
Upper-level jet stream
Lake Baikal
North ChinaDrier
Anomalous anticyclone
Weakened
Anomalousdescendingflows
Figure 11 Schematic diagram of mechanism for the halt of the increasing trend of summer rainfall over North China since the mid-1990s
8 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
warming of Lake Baikal the standardized time series of theaveraged summer SAT over Lake Baikal (40degNndash60degN80degEndash120degE) is shown in Figure 10(a) +e feature of theinterdecadal and interannual variability of SAT over LakeBaikal is apparent Mann-Kendall test method is used toinvestigate accurate abrupt point of the SATover Lake Baikalin Figure 10(b) +e abrupt year of the SATover Lake Baikalis close to the abrupt year of the summer rainfall over NorthChina
+e SAT over Lake Baikal and the summer rainfall overNorth China have experienced the interdecadal changes
since the mid-1990s +e negative correlation existing be-tween the SATover Lake Baikal and the summer rainfall overNorth China [49] suggests that the interdecadal warming ofLake Baikal contributes to the interdecadal less summerrainfall over North China+e interdecadal warming of LakeBaikal is observed not only in the lower troposphere inFigure 7(b) but also in the upper troposphere in Figure 8(a)+e interdecadal warming of Lake Baikal results in not onlythe anomalous anticyclonic circulation and anomalouspositive geopotential height over Lake Baikal in the lower andmiddle troposphere but also the weakening of the zonal wind
0
0
0
0
0
2
2
2
2
2
2
2
2
4
4
4
4
4
4
44
4
4
4
6
6
6
6
6
66
6
68
8
8
8
8
8
8
8
10
10
10
10
10
10
10
10
12
12
12
12
12
12 1214
14
1414
14
14
14
1616
1616
16
16
1818
1818
18
18
20
20
20
20
20
20
22
22
22
24
24
24
26
2628
ndash22ndash20
ndash18
ndash1 8
ndash16
ndash 16
ndash14
ndash14
ndash12
ndash12
ndash10
ndash10
ndash8
ndash8
ndash6
ndash6
ndash4
ndash4
ndash4
ndash2
ndash2
ndash2
ndash2
Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
(a)
0202
02
02
02
02
02
02
02
0 2
0202
0202
02
02
02
02
02
02
02
0 2
02
02
02
02
04
04
04
04
04
04
04
04
04
04
04 04 04
04
04
04
04
04
04
04
04
0 4
04
04
04
04 04
06
06
06
06
06
0606
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
06
08
08
08
08
08
08
08
08
08
08
08
08
08
08
08 08
08
08
08
08
08
1
1
1
1
1
1
1
1
1
1
1
1
11
1
1
1
1
1
1
1
1
12
12
12
12
12
12
14
14
141416
161616
16
1818
18
22
22
ndash06 ndash04
ndash04
ndash04
ndash02
ndash02ndash02
ndash02ndash02
ndash02
ndash02
0
00
0
00
0
0
0
0
00
0
0
0
0
0
0
0
0
0
0
0
0Lake Baikal
NC
20degN
30degN
40degN
50degN
60degN
70degN
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
06
02
(b)
Figure 7 Same as Figure 5 but for (a) 500 hPa geopotential height (unit gpm) and (b) SAT (unit degC)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
05
05
05
05
05
05
05
05
05 05 05
0505
1 1
1
1
1
1
1
1
1
1
1 11
115
15
15
15
15 15
15
15
2
2
2
2
2
25
25
25
25
3
3
3
3
35
minus5minus45minus4minus35
minus35
minus3
minus3
minus3
minus3
minus25
minus25
minus25
minus25
minus25
minus2
minus2
2
minus2
minus2
minus2
minus2
minus2
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus15
minus1
minus1
minus1 minus1
minus1
minus1
minus1
minus1minus1
minus1
minus1
minus1
minus1
minus05
minus05
minus05minus05
minus05
minus05
minus05
minus05 minus05
minus05
minus05
minus05
minus05
0
minus1 minus08 minus06 minus04 minus02 0 02 04 06 08 1
Lake Baikal
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN minus15
(a)
26
26 3026
30
30
minus30 minus25 minus20 minus15 minus10 minus5 0 5 10 15 20 25 30
Lake Baikal
NC
60degE 70degE 80degE 90degE 100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
70degN
(b)
Figure 8 (a) Same as Figure 5 but for 200 hPa zonal winds (contours unit ms) and temperature (shading unit degC) +e difference oftemperature in blue box with black dots is statistically significant at the 95 confidence level according to Studentrsquos t-test +e difference ofzonal winds with black cross is statistically significant at the 95 confidence level according to Studentrsquos t-test (b) 200 hPa zonal winds (unitms) in JA of 1979ndash1996 mean (black contours) and 1997ndash2016 mean (white contours) +e shading is the climatic mean of 200 hPa zonalwinds during 1979ndash2016 +e black box shows North China +e green box shows the region of Lake Baikal
6 Advances in Meteorology
in the upper troposphere Obviously the anomalous anti-cyclonic circulation over Lake Baikal is beneficial to less watervapor transport from the monsoon flow and the westerliesMeanwhile the weakening of the zonal wind in the uppertroposphere favors the weakening of the ascending motionand further results in the weakening of the pumping effects ofthe zonal winds in the upper troposphere +e interdecadalweakening of the ascending motion and interdecadal re-duction of the water vapor transport to North China directlylead to the interdecadal drought over North China
4 Summary and Discussion
Using the 17-station rainfall and the new GPCC full datamonthly product precipitation data sets the interdecadal
variations of the summer rainfall over North China since themid-1990s are firstly discovered in this paper +e possiblecauses such as the interdecadal variations of the atmosphericcirculation and the water vapor budget are discussed+emajormechanisms are shown in Figure 11 and summarized as follows
Summer rainfall over North China had an increasingtendency during 1979ndash1996 since 1997 this increasingtendency has halted and more summer droughts occurredover North China
+e SAT over Lake Baikal and the summer rainfall overNorth China have had interdecadal abrupt since the mid-1990s +e interdecadal warming of Lake Baikal is beneficialto the interdecadal less summer rainfall over North China
+e intense interdecadal warming of Lake Baikal resultsin not only the anomalous anticyclonic circulation and
20degN 30degN 40degN 50degN 60degN
100
150
200
300
500
700
10000
00 0
0
0
0
0
0
0
0
0 0
0
0
05
05
05
05
05
05
05
05 1
1
1
11
1
1
1
15
1515
15
2 25
335 4
minus2 minus15
minus15
minus15
minus15
minus1
minus1
minus1
minus1
minus1
minus 1
minus1minus05
minus05
minus05
minus05
minus05
minus05
minus05
minusminus05
0Figure 9 Latitude-height cross section of difference of vertical velocity along 11625degE in JA by 1997ndash2016meanminus 1979ndash1996mean (unit10minus 2 Pas) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test +e red line shows North China
Mean = ndash074
Trend = 0069year (96)
Mean = 06
1980 1985 1990 1995 2000 2005 2010 2015
ndash2ndash1012
(a)
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
4
6
UF UB
(b)
Figure 10 (a) Same as Figure 2(a) but for the summer SAT over Lake Baikal (b) Same as Figure 2(b) but for the summer SAT overLake Baikal
Advances in Meteorology 7
anomalous positive geopotential height over Lake Baikal inthe lower and middle troposphere but also the weakening ofthe zonal wind in the upper troposphere +e anomalousanticyclonic circulation in the lower troposphere over LakeBaikal results in less water vapor transport from the mon-soon flow and the westerly flow +e weakening of the zonalwind in the upper troposphere favors the weakening of theascending motion and the pumping effects of the zonalwinds in the upper troposphere+e interdecadal weakeningof the ascending motion and the less interdecadal watervapor transport result in the interdecadal drought in NorthChina
In addition to the contribution of the less water vaportransport from weakened monsoon flow to the summerrainfall over North China the interdecadal reduction of thewater vapor transport from western boundary to NorthChina is also responsible for the halted rainfall tendencyover North China since the mid-1990s which is usuallyignored
+ere are many other factors that also contribute to theinterdecadal variation of the summer rainfall over NorthChina [6] such as Pacific decadal oscillation [52] arcticsea ice [44] and Tibet Plateau snow cover [53] +esefactors and climate model verification are worthy offurther study
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work is supported by the Strategic Priority ResearchProgram of Chinese Academy of Sciences (XDA20100304)the State Key Program of the National Natural ScienceFoundation of China (41475051 41875111) the StartingFoundation of the Civil Aviation University of China(2016QD05X) and the Research Foundation of the CivilAviation University of China (3122015D019)
References
[1] L Han S Li and N Liu ldquoAn approach for improving short-term prediction of summer rainfall over North China bydecomposing interannual and decadal variabilityrdquo Advancesin Atmospheric Sciences vol 31 no 2 pp 435ndash448 2014
[2] Z Yan J Ji and D Ye ldquoNorthern hemispheric summerclimatic jump in the 1960rsquos (I)mdashrainfall and temperaturerdquoScience in China (Series B) vol 33 no 9 pp 1092ndash1101 1990
[3] A Yatagai and T Yasunari ldquoTrends and decadal-scale fluc-tuations of surface air temperature and precipitation overChina and Mongolia during the recent 40 year period (1951-1990)rdquo Journal of the Meteorological Society of Japan Ser IIvol 72 no 6 pp 937ndash957 1994
[4] T Nitta and Z-Z Hu ldquoSummer climate variability in Chinaand its association with 500 hPa height and tropical con-vectionrdquo Journal of theMeteorological Society of Japan vol 74no 4 pp 425ndash445 1996
60degE70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
60deg E70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
20degN
30degN
40degN
50degN
60degN
1997ndash2016 minus 1979ndash1996
850hPa
200hPa
Upper-level jet stream
Lake Baikal
North ChinaDrier
Anomalous anticyclone
Weakened
Anomalousdescendingflows
Figure 11 Schematic diagram of mechanism for the halt of the increasing trend of summer rainfall over North China since the mid-1990s
8 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
in the upper troposphere Obviously the anomalous anti-cyclonic circulation over Lake Baikal is beneficial to less watervapor transport from the monsoon flow and the westerliesMeanwhile the weakening of the zonal wind in the uppertroposphere favors the weakening of the ascending motionand further results in the weakening of the pumping effects ofthe zonal winds in the upper troposphere +e interdecadalweakening of the ascending motion and interdecadal re-duction of the water vapor transport to North China directlylead to the interdecadal drought over North China
4 Summary and Discussion
Using the 17-station rainfall and the new GPCC full datamonthly product precipitation data sets the interdecadal
variations of the summer rainfall over North China since themid-1990s are firstly discovered in this paper +e possiblecauses such as the interdecadal variations of the atmosphericcirculation and the water vapor budget are discussed+emajormechanisms are shown in Figure 11 and summarized as follows
Summer rainfall over North China had an increasingtendency during 1979ndash1996 since 1997 this increasingtendency has halted and more summer droughts occurredover North China
+e SAT over Lake Baikal and the summer rainfall overNorth China have had interdecadal abrupt since the mid-1990s +e interdecadal warming of Lake Baikal is beneficialto the interdecadal less summer rainfall over North China
+e intense interdecadal warming of Lake Baikal resultsin not only the anomalous anticyclonic circulation and
20degN 30degN 40degN 50degN 60degN
100
150
200
300
500
700
10000
00 0
0
0
0
0
0
0
0
0 0
0
0
05
05
05
05
05
05
05
05 1
1
1
11
1
1
1
15
1515
15
2 25
335 4
minus2 minus15
minus15
minus15
minus15
minus1
minus1
minus1
minus1
minus1
minus 1
minus1minus05
minus05
minus05
minus05
minus05
minus05
minus05
minusminus05
0Figure 9 Latitude-height cross section of difference of vertical velocity along 11625degE in JA by 1997ndash2016meanminus 1979ndash1996mean (unit10minus 2 Pas) Shaded areas are statistically significant at the 95 confidence level according to Studentrsquos t-test +e red line shows North China
Mean = ndash074
Trend = 0069year (96)
Mean = 06
1980 1985 1990 1995 2000 2005 2010 2015
ndash2ndash1012
(a)
1980 1985 1990 1995 2000 2005 2010 2015
ndash2
0
2
4
6
UF UB
(b)
Figure 10 (a) Same as Figure 2(a) but for the summer SAT over Lake Baikal (b) Same as Figure 2(b) but for the summer SAT overLake Baikal
Advances in Meteorology 7
anomalous positive geopotential height over Lake Baikal inthe lower and middle troposphere but also the weakening ofthe zonal wind in the upper troposphere +e anomalousanticyclonic circulation in the lower troposphere over LakeBaikal results in less water vapor transport from the mon-soon flow and the westerly flow +e weakening of the zonalwind in the upper troposphere favors the weakening of theascending motion and the pumping effects of the zonalwinds in the upper troposphere+e interdecadal weakeningof the ascending motion and the less interdecadal watervapor transport result in the interdecadal drought in NorthChina
In addition to the contribution of the less water vaportransport from weakened monsoon flow to the summerrainfall over North China the interdecadal reduction of thewater vapor transport from western boundary to NorthChina is also responsible for the halted rainfall tendencyover North China since the mid-1990s which is usuallyignored
+ere are many other factors that also contribute to theinterdecadal variation of the summer rainfall over NorthChina [6] such as Pacific decadal oscillation [52] arcticsea ice [44] and Tibet Plateau snow cover [53] +esefactors and climate model verification are worthy offurther study
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work is supported by the Strategic Priority ResearchProgram of Chinese Academy of Sciences (XDA20100304)the State Key Program of the National Natural ScienceFoundation of China (41475051 41875111) the StartingFoundation of the Civil Aviation University of China(2016QD05X) and the Research Foundation of the CivilAviation University of China (3122015D019)
References
[1] L Han S Li and N Liu ldquoAn approach for improving short-term prediction of summer rainfall over North China bydecomposing interannual and decadal variabilityrdquo Advancesin Atmospheric Sciences vol 31 no 2 pp 435ndash448 2014
[2] Z Yan J Ji and D Ye ldquoNorthern hemispheric summerclimatic jump in the 1960rsquos (I)mdashrainfall and temperaturerdquoScience in China (Series B) vol 33 no 9 pp 1092ndash1101 1990
[3] A Yatagai and T Yasunari ldquoTrends and decadal-scale fluc-tuations of surface air temperature and precipitation overChina and Mongolia during the recent 40 year period (1951-1990)rdquo Journal of the Meteorological Society of Japan Ser IIvol 72 no 6 pp 937ndash957 1994
[4] T Nitta and Z-Z Hu ldquoSummer climate variability in Chinaand its association with 500 hPa height and tropical con-vectionrdquo Journal of theMeteorological Society of Japan vol 74no 4 pp 425ndash445 1996
60degE70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
60deg E70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
20degN
30degN
40degN
50degN
60degN
1997ndash2016 minus 1979ndash1996
850hPa
200hPa
Upper-level jet stream
Lake Baikal
North ChinaDrier
Anomalous anticyclone
Weakened
Anomalousdescendingflows
Figure 11 Schematic diagram of mechanism for the halt of the increasing trend of summer rainfall over North China since the mid-1990s
8 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
anomalous positive geopotential height over Lake Baikal inthe lower and middle troposphere but also the weakening ofthe zonal wind in the upper troposphere +e anomalousanticyclonic circulation in the lower troposphere over LakeBaikal results in less water vapor transport from the mon-soon flow and the westerly flow +e weakening of the zonalwind in the upper troposphere favors the weakening of theascending motion and the pumping effects of the zonalwinds in the upper troposphere+e interdecadal weakeningof the ascending motion and the less interdecadal watervapor transport result in the interdecadal drought in NorthChina
In addition to the contribution of the less water vaportransport from weakened monsoon flow to the summerrainfall over North China the interdecadal reduction of thewater vapor transport from western boundary to NorthChina is also responsible for the halted rainfall tendencyover North China since the mid-1990s which is usuallyignored
+ere are many other factors that also contribute to theinterdecadal variation of the summer rainfall over NorthChina [6] such as Pacific decadal oscillation [52] arcticsea ice [44] and Tibet Plateau snow cover [53] +esefactors and climate model verification are worthy offurther study
Data Availability
+e data used to support the findings of this study areavailable from the corresponding author upon request
Conflicts of Interest
+e authors declare that they have no conflicts of interest
Acknowledgments
+is work is supported by the Strategic Priority ResearchProgram of Chinese Academy of Sciences (XDA20100304)the State Key Program of the National Natural ScienceFoundation of China (41475051 41875111) the StartingFoundation of the Civil Aviation University of China(2016QD05X) and the Research Foundation of the CivilAviation University of China (3122015D019)
References
[1] L Han S Li and N Liu ldquoAn approach for improving short-term prediction of summer rainfall over North China bydecomposing interannual and decadal variabilityrdquo Advancesin Atmospheric Sciences vol 31 no 2 pp 435ndash448 2014
[2] Z Yan J Ji and D Ye ldquoNorthern hemispheric summerclimatic jump in the 1960rsquos (I)mdashrainfall and temperaturerdquoScience in China (Series B) vol 33 no 9 pp 1092ndash1101 1990
[3] A Yatagai and T Yasunari ldquoTrends and decadal-scale fluc-tuations of surface air temperature and precipitation overChina and Mongolia during the recent 40 year period (1951-1990)rdquo Journal of the Meteorological Society of Japan Ser IIvol 72 no 6 pp 937ndash957 1994
[4] T Nitta and Z-Z Hu ldquoSummer climate variability in Chinaand its association with 500 hPa height and tropical con-vectionrdquo Journal of theMeteorological Society of Japan vol 74no 4 pp 425ndash445 1996
60degE70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
60deg E70degE
80degE90degE
100degE 110degE 120degE 130degE 140degE 150degE
20degN
30degN
40degN
50degN
60degN
20degN
30degN
40degN
50degN
60degN
1997ndash2016 minus 1979ndash1996
850hPa
200hPa
Upper-level jet stream
Lake Baikal
North ChinaDrier
Anomalous anticyclone
Weakened
Anomalousdescendingflows
Figure 11 Schematic diagram of mechanism for the halt of the increasing trend of summer rainfall over North China since the mid-1990s
8 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
[5] R Huang Y Xu and L Zhou ldquo+e interdecadal variation ofsummer precipitations in China and the drought trend inNorth Chinardquo Plateau Meteorology vol 18 pp 456ndash4761999
[6] R Lu ldquoInterdecadal variations of precipitations in variousmonths of summer in North Chinardquo Plateau Meteorologyvol 18 no 4 pp 510ndash519 1999
[7] X Dai P Wang and J Chou ldquoMultiscale characteristics ofthe rainy season rainfall and interdecadal decaying of summermonsoon in North Chinardquo Chinese Science Bulletin vol 48no 24 pp 2730ndash2734 2003
[8] Y Zhu H Wang W Zhou and J Ma ldquoRecent changes in thesummer precipitation pattern in East China and the back-ground circulationrdquo Climate Dynamics vol 36 no 7-8pp 1463ndash1473 2011
[9] R Lu ldquoLinear relationship between the interdecadal andinterannual variabilities of North China rainfall in rainyseasonrdquo Chinese Science Bulletin vol 48 no 10pp 1040ndash1044 2003
[10] Y Ding Z Wang and Y Sun ldquoInter-decadal variation of thesummer precipitation in East China and its association withdecreasing Asian summer monsoonmdashpart I observed evi-dencesrdquo International Journal of Climatology vol 28 no 9pp 1139ndash1161 2008
[11] F Liang S Tao J Wei and C Bueh ldquoVariation in summerrainfall in North China during the period 1956ndash2007 and linkswith atmospheric circulationrdquo Advances in AtmosphericSciences vol 28 no 2 pp 363ndash374 2011
[12] H Wang ldquo+e weakening of the Asian monsoon circulationafter the end of 1970rsquosrdquo Advances in Atmospheric Sciencesvol 18 no 3 pp 376ndash386 2001
[13] R Wu and B Wang ldquoA contrast of the East Asian summermonsoon-ENSO relationship between 1962ndash77 and 1978ndash93rdquoJournal of Climate vol 15 no 22 pp 3266ndash3279 2002
[14] J Han and H Wang ldquoFeatures of interdecadal changes of theEast Asian summer monsoon and similarity and discrepancyin ERA-40 and NCEPNCAR reanalysis datardquo ChineseJournal of Geophysics vol 56 no 6 pp 1666ndash1676 2007
[15] M Kwon J G Jhun B Wang et al ldquoDecadal change inrelationship between east Asian and WNP summer mon-soonsrdquoGeophysical Research Letters vol 32 no 16 Article IDL16709 2005
[16] S-Y Yim J-G Jhun and S-W Yeh ldquoDecadal change in therelationship between east Asian-western North Pacific sum-mer monsoons and ENSO in the mid-1990srdquo GeophysicalResearch Letters vol 35 no 20 Article ID L20711 2008
[17] Y Kajikawa and B Wang ldquoInterdecadal change of the SouthChina Sea summer monsoon onsetrdquo Journal of Climatevol 25 no 9 pp 3207ndash3218 2012
[18] S-Y Yim B Wang and M Kwon ldquoInterdecadal change ofthe controlling mechanisms for East Asian early summerrainfall variation around the mid-1990srdquo Climate Dynamicsvol 42 no 5-6 pp 1325ndash1333 2014
[19] H Yao Z Zhong H Chen et al ldquoOut of phase decadalchanges in boreal summer rainfall between Yellow-Huaiheriver valley and southern China around 20022003rdquo ClimateDynamics vol 47 no 1-2 pp 137ndash158 2016
[20] J Chen Z Wen R Wu X Wang C He and Z Chen ldquoAninterdecadal change in the intensity of interannual variabilityin summer rainfall over southern China around early 1990srdquoClimate Dynamics vol 48 no 1-2 pp 191ndash207 2017
[21] RWu ZWen S Yang and Y Li ldquoAn interdecadal change inSouthern China summer rainfall around 199293rdquo Journal ofClimate vol 23 no 9 pp 2389ndash2403 2010
[22] Z Yan J Ji and D Ye ldquoNorthern hemispheric summer climaticjump in the 1960rsquos (II)mdashsea level pressure and 500 hPa heightrdquoScience China Chemistry vol 34 no 4 pp 87ndash96 1991
[23] C Li and Q Liao ldquoQuasi-Decadal oscillation of climate inEast AsiaNorthwestern Pacific region and possible mecha-nismrdquo Climate and Environmental Research vol 1 no 2pp 124ndash133 1996
[24] B Wu R Huang and D Gao ldquoImpacts of long-range var-iations of winter sea-ice extents in Arctic on rainfall in NorthChinardquo Plateau Meteorology vol 18 pp 590ndash594 1999
[25] C Li and G Li ldquoVariation of the NAO and NPO associatedwith climate jump in the 1960srdquo Chinese Science Bulletinvol 44 no 21 pp 1983ndash1987 1999
[26] Z-Z Hu ldquoInterdecadal variability of summer climate overEast Asia and its association with 500 hPa height and globalsea surface temperaturerdquo Journal of Geophysical ResearchAtmospheres vol 102 no D16 pp 19403ndash19412 1997
[27] R Yu and T Zhou ldquoSeasonality and three-dimensionalstructure of interdecadal change in the East Asian monsoonrdquoJournal of Climate vol 20 no 21 pp 5344ndash5355 2007
[28] Y Zhang J M Wallace and D S Battisti ldquoENSO-likeinterdecadal variability 1900ndash93rdquo Journal of Climate vol 10no 5 pp 1004ndash1020 1997
[29] C-P Chang Y Zhang and T Li ldquoInterannual and inter-decadal variations of the East Asian summer monsoon andtropical Pacific SSTsmdashpart I roles of the subtropical ridgerdquoJournal of Climate vol 13 no 24 pp 4326ndash4340 2000
[30] F Yang and K M Lau ldquoTrend and variability of Chinaprecipitation in spring and summer linkage to sea-surfacetemperaturesrdquo International Journal of Climatology vol 24no 24 pp 1625ndash1644 2004
[31] S Menon J Hansen L Nazarenko et al ldquoClimate effects ofblack carbon aerosols in China and Indiardquo Science vol 297no 5590 pp 2250ndash2253 2002
[32] H Tian P Guo and W Lu ldquoCharacteristics of vapor inflowcorridors related to summer rainfall in China and impact factorsrdquoJournal of Tropical Meteorology vol 20 no 4 pp 401ndash408 2004
[33] X Zhou Y Ding and P Wang ldquoMoisture transport in Asiansummer monsoon region and its relationship with summerprecipitation in Chinardquo Acta Meteorologica Sinica vol 24no 1 pp 31ndash42 2008
[34] R Huang Z Zhang and GHuang ldquoCharacteristics of the watervapor transport in east Asian monsoon region and its differencefrom that in south Asian monsoon region in summerrdquo ScientiaAtmospherica Sinica vol 22 pp 460ndash469 1998
[35] K A McKinnon and C Deser ldquoInternal variability and re-gional climate trends in an observational large ensemblerdquoJournal of Climate vol 31 no 17 pp 6783ndash6802 2018
[36] G Srinivas J S Chowdary Y Kosaka C GnanaseelanA Parekh and K V S R Prasad ldquoInfluence of the Pacific-Japan pattern on Indian summer monsoon rainfallrdquo Journalof Climate vol 31 no 10 pp 3943ndash3958 2018
[37] Y Xu and A Hu ldquoHow would the twenty-first-centurywarming influence pacific decadal variability and its con-nection to North American rainfall assessment based on arevised procedure for the IPOPDOrdquo Journal of Climatevol 31 no 4 pp 1547ndash1563 2018
[38] D P Dee S M Uppalaa and A J Simmons ldquo+e ERA-interim reanalysis configuration and performance of the dataassimilation systemrdquo Quarterly Journal of the Royal Meteo-rological Society vol 137 pp 553ndash597 2011
[39] A Ebita S Kobayashi Y Ota et al ldquo+e Japanese 55-yearreanalysis ldquoJRA-55rdquo an interim reportrdquo Sola vol 7pp 149ndash152 2011
Advances in Meteorology 9
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology
[40] H B Mann ldquoNon-parametric tests against trendrdquo Econo-metrica vol 13 no 3 pp 163ndash171 1945
[41] M G Kendall Rank Correlation Methods Charles GriffinLondon UK 4th edition 1975
[42] D S Wilks Statistical Methods in the Atmospheric SciencesOxford Academic Press Oxford UK 3rd edition 2011
[43] J T Schmitz and S L Mullen ldquoWater vapor transport as-sociated with the summertime North American monsoon asdepicted by ECMWF analysesrdquo Journal of Climate vol 9no 7 pp 1621ndash1634 1996
[44] H Wang and S He ldquo+e North ChinaNortheastern Asiasevere summer drought in 2014rdquo Journal of Climate vol 28no 17 pp 6667ndash6681 2015
[45] H Liu T Zhou Y Zhu and Y Lin ldquo+e strengthening EastAsia summer monsoon since the early 1990srdquo Chinese ScienceBulletin vol 57 no 13 pp 1553ndash1558 2012
[46] Q Xu ldquoAbrupt change of the mid-summer climate in centraleast China by the influence of atmospheric pollutionrdquo At-mospheric Environment vol 35 no 30 pp 5029ndash5040 2001
[47] Z Hu S Yang and R Wu ldquoLong-term climate variations inChina and global warming signalsrdquo Journal of GeophysicalResearch vol 108 no D19 p 4614 2003
[48] T Zhou D Gong J Li and B Li ldquoDetecting and under-standing the multi-decadal variability of the East Asiansummer monsoon recent progress and state of affairsrdquoMeteorologische Zeitschrift vol 18 no 4 pp 455ndash467 2009
[49] K Xu C Zhu and J He ldquoImpact of the surface air tem-perature warming around Lake Baikal on trend of summerprecipitation in North China in the past 50 yearsrdquo PlateauMeteorology vol 30 no 2 pp 309ndash317 2011
[50] K Xu J He H Zhu et al ldquo+e interdecadal linkage of thesummer precipitation in eastern China with the surface airtemperature over Lake Baikal in the past 50 yearsrdquo ActaMeteorologica Sinica vol 69 no 4 pp 570ndash580 2011
[51] D-Q Huang J Zhu Y-C Zhang and A-N Huang ldquo+edifferent configurations of the East Asian polar front jet andsubtropical jet and the associated rainfall anomalies overeastern China in summerrdquo Journal of Climate vol 27 no 21pp 8205ndash8220 2014
[52] C Zhu B Wang W Qian et al ldquoRecent weakening ofnorthern east asian summer monsoon a possible response toglobal warmingrdquo Geophysical Research Letters vol 39 no 9Article ID L09701 2012
[53] B Wang Q Bao B Hoskins G Wu and Y Liu ldquoTibetanPlateau warming and precipitation changes in East AsiardquoGeophysical Research Letters vol 35 no 14 Article IDL14702 2008
10 Advances in Meteorology