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2010
Annual Report
Hydrospheric Atmospheric Research Center (HyARC)
Nagoya University
NAGOYAUNIVERSITY
2010
drospheric tmosphericesearch enter
(HyARC)
Contents
Foreword 2
Staff and Organization 3
Research Programme 6
Progress Reports Projects 8 DivisionofRegional–ScaleWaterCycleProcesses 12 LaboratoryofMeteorology 12 LaboratoryforClimateSystemStudy 18 LaboratoryforCloudandPrecipitationClimatology 22
DivisionofGlobal–ScaleWaterCycleVariations 24 LaboratoryofSatelliteMeteorology 24 LaboratoryofSatelliteBiologicalOceanography 26 LaboratoryofBio-PhysicalOceanography 30 List of Publications 32
2 Foreword
TheHydrosphericAtmosphericResearchCenter(HyARC)atNagoyaUniversity
wasestablished10yearsagotopromoteresearchontheglobalwatercycle,whichis
aprimarycomponentoftheearthsystem.Researchontheglobalwatercyclerequires
strongandextensivecollaborationamongscienceandapplicationcommunities.There-
fore,HyARCfunctionsasaninter-universitycollaborativesystem,whichisinmany
waysuniqueintheworld.InordertoensuretheactivityHyARChasbeenaccredited
asaJointUsage/ResearchCentersinceApril2010bytheMinistryofEducation,Cul-
ture,Sports,ScienceandTechnology,Japan.
HyARChasinitiatednumerousprojectsandactivities.Prominentamongtheseis
theInternationalProjectOfficefortheGlobalEnergyandWaterCycleExperiment
(GEWEX) Asian Monsoon Experiment (GAME) led by Prof. T. Yasunari, and its
various follow-onprojects.Additionalworkhasbeensupportedby the following:
Grants-in-Aid forScientificResearch;CoreResearch forEvolutionalScienceand
Technology (CREST)of JapanScienceandTechnologyCorporation (JST);Global
EnvironmentResearchFund;InnovativeProgramofClimateChangeProjectionfor
the21stCentury;andmore.Inaddition,fundingfromtheMinistryofEducation,
Culture, Sports, Science and Technology, Japan, supported the construction of a
multiparameterradarsystemtostudywatercirculation,andfundingfromtheInter-
UniversityProjectsupportedavirtuallaboratoryfordiagnosingtheearth’sclimate
system.
HyARChasalsocollaboratedwithnumerousinstitutionssuchasResearchInsti-
tute of Humanity and Nature (RIHN) and National Institute of Information and
CommunicationTechnology(NICT).AspartialcontributiontotheUNESCOInter-
nationalHydrologyProgramme(IHP),HyARChasconductedtrainingcoursessup-
portedbytheJapanTrustFund.Thisyear’scoursewasonsatelliteremotesensing
ofatmosphericconstituents.
Whileselectingprojectsandactivities,HyARCconsidersprojectfeasibility,sig-
nificance,andcollaborationrequirements.Itcurrentlyfundsthreeresearchprojects
andfourworkshops.AlthoughHyARChasonly10permanentstaffmembers(four
professors, threeassociateprofessors, and threeassistantprofessors), it supports
manypostdoctoralcandidatesinactiveresearch.Inaddition,HyARChasaccepted
graduatestudentsintheDepartmentofEnvironmentalStudies.
NagoyaUniversityhasadoptedaflexiblemanagementsystemthatemphasizes
accountability,yetencouragesresearchpublicationsandoutreachprograms.With
theencouragementprovidedbyanexternalevaluationcommittee,weherewithpro-
posetoestablishalarge-scalenational/internationalfacilityandaneworganization
foraddressingitssocialrequirements.
Uyeda HiroshiDirector
HydrosphericAtmosphericResearchCenter
3Staff and Organization
Research Division Division of Regional – Scale Water Cycle Processes
Professor
Assoc. Professor
Assist. Professor
Designated Assist. Professor
VL Promotion Unit
AdministrativeDirector
AdministrativeVice-Director
UYEDA Hiroshi
TSUBOKI Kazuhisa
SHINODA Taro
OHIGASHI Tadayasu
YASUNARI Tetsuzo
MASUNAGA Hirohiko
FUJINAMI Hatsuki
Division of Global – Scale Water Cycle Variations
Professor NAKAMURA Kenji
MORIMOTO Akihiko
Assist. Professor MINO Yoshihisa
ISHIZAKA Joji
Technical Office (Technical Center) MINDA Haruya
Secretary Office
Administrative Office
IWAMOTO Keiko
TANIGUCHI Tetsuya
SUGIE Osamu
General Affairs Section
Board of Councilors
Director
AdvisoryBoard
Board onResearch
Collaboration
Assoc. Professor
Designated Assist. Professor TANAKA Hiroki
Accounting Section
Research Promotion Section
Supplies Section
Student Affairs Section
4
Administration
UYEDA Hiroshi: Director, Prof., Hydrospheric Atmospheric Research Center, Nagoya University
NAKAMURA Kenji: Prof., Hydrospheric Atmospheric Research Center, Nagoya University
YASUNARI Tetsuzo: Prof., Hydrospheric Atmospheric Research Center, Nagoya University
ISHIZAKA Joji: Prof., Hydrospheric Atmospheric Research Center, Nagoya University
TANAKA Kentaro: Prof., Graduate School of Science, Nagoya University
TSUJIMOTO Tetsuro: Prof., Graduate School of Engineering, Nagoya University
TAKENAKA Chisato: Prof., Graduate School of Bioagricultural Sciences, Nagoya University
KANZAWA Hiroshi: Prof., Graduate School of Environmental Studies, Nagoya University
MATSUMI Yutaka: Prof., Solar-Terrestrial Environment Laboratory, Nagoya University
Advisory Board
lMembersfromNagoyaUnisversity
NAKAMURAKenji:Prof., Hydrospheric Atmospheric Research Center, Nagoya University
YASUNARITetsuzo:Prof., Hydrospheric Atmospheric Research Center, Nagoya University
ISHIZAKAJoji:Prof., Hydrospheric Atmospheric Research Center, Nagoya University
TSUBOKIKazuhisa:Assoc. Prof., Hydrospheric Atmospheric Research Center, Nagoya University
MASUNAGAHirohiko: Assoc. Prof., Hydrospheric Atmospheric Research Center, Nagoya University
MORIMOTOAkihiko: Assoc. Prof., Hydrospheric Atmospheric Research Center, Nagoya University
lMembersoutsideNagoyaUniversity
FUJIYOSHIYasushi:Prof., Institute of Low Temperature Science, Hokkaido University
HANAWAKimio:Prof., Graduate School of Science, Tohoku University
SUMIAkimasa: Prof., Integrated Research System for Sustainability Science,
The University of Tokyo
FUKUSHIMAYoshihiro:Designated Prof., Tottori University of Environmental Studies
YAMANAKAManabu: Principal Scientist, Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology
YAMANOUCHITakashi:Prof., National Institute of Polar Research
TANIGUCHIMakoto:Prof., Research Institute for Humanityand Nature
OKIRiko:Senior Researcher, Earth Observation Research Center, Japan Aerospace Exploration Agency
Board of Councilors
5
Board on Research Collaboration
lMembersfromNagoyaUniversity
NAKAMURAKenji:Prof., Hydrospheric Atmospheric Research Center, Nagoya University
ISHIZAKAJoji:Prof., Hydrospheric Atmospheric Research Center, Nagoya University
MORIMOTOAkihiko:Assoc. Prof., Hydrospheric Atmospheric Research Center, Nagoya University
lMembersoutsideNagoyaUniversity
FUJIYOSHIYasushi: Prof., Institute of Low Temperature Science, Hokkaido University
YAMANAKAManabu:Principal Scientist, Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology
TANIGUCHIMakoto:Prof., Research Institute for Humanityand Nature
OKIRiko:Senior Researcher, Earth Observation Research Center, Japan Aerospace Exploration Agency
6 Research Programme
Water circulation studies using new polarimetric radars
In2007,newpolarimetric(multiparameter)radarswereinstalledattheHydrosphericAtmosphericResearchCenter(HyARC),NagoyaUniversity.Sinceitsinstallation,thisequip-menthasbeenpromotingnewstudiesoncloudsandprecipitation,thusaidinginthedevelop-mentofnewobservationalandanalyticaltechniquesthatareessentialforstudiesonwatercirculation.Suchobservationalandanalyticaltechniquesaswellasdataassimilationmethodsarenecessaryforutilizingobservationaldatafromthenewradarsandforamalgamatingthedatawithacloud-resolvingmodel. Thisresearchprogramaimsatpromotingresearchonwatercirculationusingthenewpolarimetricradarsandexistingradarsets.Inparticular,weexamineandimplementobser-vationaldataofweatherphenomenaandphysicalprocessesofcloudandprecipitationsystems.Weaimatdevelopingnewparametersformultiparameterradarobservationsanddataanal-ysisandnewdisplaymethodsforradardata.Wewilldevelopsoftwareandoperationalroutinesfortheradarequipmentfromphysicalandengineeringviewpointsincollaborationwithre-searchersparticipatinginthisstudyproject.
Diurnal processes of convection/precipitation systems in the climate System
Diurnalvariationinconvectionandprecipitationisaprominentmeteorologicalfeature,particularlyinthetropics/subtropicsandmonsoonregions.Energy,water,andmomentumexchangesthroughthediurnalcyclebetweentheearthsurface,atmosphericboundarylayer,andfreeatmosphereplayacrucialrole inglobalclimatemodels(GCMs)andstillcannotreproducearealisticdiurnalcycleinconvection/precipitation,includingsystematicerrorsinthemodels. Thisresearchplanaimstoclarify theregionalityandseasonalityofdiurnalprocessesbasedonTRMM,otherremotesensingdata,andin-situobservationaldatafromraingaugestations.Cloudresolvingmodels(e.g.,CReSSandWRF)andotherregionalmodelsarealsousedtoelucidatesystematicerrorsintheclimatemodelduetothediurnalcycle.Thesestud-iescancontributetotheongoinginternationalproject“MAHASRI.”Weaimtopromotestud-iesonthediurnalprocessofconvection/precipitationintheclimatesysteminJapan. OnDecember19,2007,adomesticworkshop,co-hostedbyMAHASRI,washeldinHakone.Studiesonthediurnalvariationofcloud/precipitationsystems, includingtherelationshipwithterrain,synopticconditionsandintraseasonalvariation,werepresented.ThesestudiescoveredareasfromtheTibetanPlateautotheMaritimecontinents.Intotal,14participantspresentednewscientificresultsandtherewasalivelydiscussionwithmanyparticipantsintheworkshop.Futureissuesondiurnalcycleswerealsodiscussed.
7
Study of atmospheric and oceanic climates over Okinawa Island and its surroundings
TheOkinawaSubtropicalEnvironmentRemote-SensingCenter,anobservationfacilityinOkinawa,Japan,wasestablishedbytheTheNationalInstituteofInformationandCom-municationTechnology (NICT).These facilitiesoffer theuseof fullpolarimetricDopplerradar(COBRA),400MHzwindprofilerradar,Dopplersodar,disdrometers,raingauges,andoceanradars.In2005,aninteruniversitycollaborationwasformedbetweenNICT,Okinawa,andtheHydrosphericAtmosphericResearchCenteratNagoyaUniversity,Japan(HyARC). Severalinterestingphenomena,suchasacoldwaterappearanceinnorthernTaiwanafteratyphoon,havebeenreported.Newobservations,suchasadual-Karadarsystemobserva-tion,havealsobeenintroduced.Thedirectionofthenextstepwasdiscussed,andtwodirec-tionshavebeen identified: (a)flexibleocean radardevelopmentandapplicationsand (b)Ka-bandradarobservationwithaversatileC-bandDopplerradar. Thescientificobjectivesarenotalwaysconcrete;however, the technology toremotelyobserveatmosphericandoceanicphenomenaissimilar.NICTdevelopsradiowavessensors,andHyARCorganizestheexplorationofdeeperandwiderapplications.Theimportanceofthecollaborationiswellrecognized.
8 Projects
PROgReSS RePORtS
Formation of a virtual laboratory for diagnosing the earth’s climate sys-tem (VL)
Toconductcollaborativeresearchandprovideeducationinaddressinghigh-stressfactorssuchasglobalwarming,avirtuallaboratoryfordiagnosingtheEarth’sclimatesystem(VL)wasformedin2007byfouruniversityresearchcentersstudyingclimateandenvironment.HyARCsetuptheAtmosphericResearchPromotionTeam(VLPromotionTeam)toprogressthecollaborativeresearch.Wefocusourstudiesonwaterbudgetsassociatedwithcloudsandprecipitationanddevelopanobservationandanalysissystem.WeanalyzetwopolarimetricDopplerradardatatodiagnoseacategoryofhydrometeorparticles,developacloud-resolvingmodelknownasCloudResolvingStormSimulator(CReSS),validateitsresultsusingasatel-litesimulatorknownasSatelliteDataSimulationUnit(SDSU),andestablishadataassimila-tionmethodforamesoscaleprecipitationsystem. In2010,weperformedcontinuousobservationwithapolarimetricDopplerradarlocatedatNagoyaUniversity.AheavyrainfalleventoccurredinthesoutheasternregionofGifuPre-fectureonJuly15,2010.ThestructureoftheprecipitationsystemwasclarifiedusingthepolarimetricradarandwasaccuratelyreproducedusingCReSS.Inaddition,thelightningfrequencywasreproducedusingCReSSLightningSimulator.Moreover,weusedpolarimetricradardatatoconductstatisticalanalysisofprecipitationcellsovertheNobiPlain. Wecomparedbrightnesstemperatures(TBBs)ofinfraredandmicrowavebandsobtainedfromsatelliteobservationswiththosecalculatedbySDSUappliedtothedailysimulationresultsusingCReSS.SatellitedatawereprovidedbyCenterforEnvironmentalRemoteSens-ing(CEReS),ChibaUniversity,undertheframeworkofVL.Figureshowshorizontaldistribu-tionsofTBBforinfraredbandobtainedbysatelliteobservationandsimulationovertheTai-wan–Okinawaregion.Twowell-developedMesoscaleConvectiveSystems(MCSs)withmini-mumTBBlessthan200KdevelopedoverthesoutheastandsouthwestareasfarfromTaiwanIslandinsatelliteobservation.ThesoutheasternMCScanbereproducedinthesimulation.WewillconfirmbiasesandimprovetheaccuracyofthemicrophysicalprocessesofCReSSincomparisonsimulationresultswithsatelliteobservationsstatistically,.
Fig. HorizontaldistributionsofTBBfortheinfraredbandobtainedbysatelliteobservation(MTSAT-CH1:left)andsimulation(CReSS-SDSU:right)at17UTConMay29,2010overtheTaiwan–Okinawaregion.
9
the Innovative Program of Climate Change Projection for the 21st Cen-tury (KAKUSHIN Program)
lCloud Modeling and Typhoon Research
Cloudphysics isoneof thekeyprocesses formodelingclimatechange,especially forglobalwarming.Improvingcloudprocessesisessentialforaccuratesimulations.Cloudpro-cessesarealsocoreprocessesinsimulationsofhigh-impactweathersystemssuchasheavyrainfallsandtyphoons.Thecloudmodelingteamhasbeendevelopingacloud-resolvingmod-elcalledtheCloudResolvingStormSimulator(CReSS).Thecloudmicrophysicsandcom-putationschemeofCReSSareimprovedforaccurateandhigh-speedcalculation.Convectivecloudsinthetropicalregionandtyphoonsareimportantobjectsofourteam.TheCReSSmodelisalsocoupledwithglobalmodelstosimulateconvectiveregions.CReSSisusedfortyphoonresearch,whichaimstohelpverifytyphoonsimulationsmadebyglobalmodelsandtoproduceaccurateandquantitativeevaluationsoftyphooneffectsonhumansocietyunderthepresentandfutureclimates. Occasionally,typhoonscauseseveredisastersowingtoheavyrainfallandstrongwinds.Ontheotherhand,theybringalargeamountofwatertotheEastAsiancountries.Changesintyphoonswithglobalwarming,therefore,havealargeimpactonhumansociety.Becausetyphoonsarecomposedofintenseconvectivecloudsandassociatedstratiformclouds,acloud-resolvingsimulationisnecessarytoaccuratelypredicttheirintensity.Inthepresentstudy,wehavedevelopedanewtechniqueforperformingaparallelcomputationofthecloud-resolvingmodel in anarbitrary-shaped region,which isnamed the “TilingDomain Technique” forCReSS.Thefigureshowsathree-dimensionaldisplayofsimulatedcloudsassociatedwiththetyphoonoverTaiwanin2009.TheeyewallaroundtheeyeislocatedoverTaiwan.ThecloudbandtothesouthoftheeyecausedheavyrainfallinsouthernTaiwan.Thesimulationshowsthatthecloud-resolvingsimulationenablesustoquantitativelypredictthetyphoonintensity.BycollaboratingwiththeotherteamoftheKAKUSHINprogram,ourteamperformedsimu-lationexperimentsoftyphoonsintheglobalwarmingclimateandfoundthatextremelyintensetyphoons,whichhaveneveroccurredinthepresentclimate,willoccurinthefutureclimates.
Fig.Three-dimensionaldisplayofsimulatedtyphoonNo.8in2009usingPOV-Ray.Thewhiteshadingshowsthemixingratioofcloudwaterat02UTCAugust8,2009.
10
Study consortium for earth-Life Interactive System (SeLIS)
TheStudyconsortiumu forEarth-Life InteractiveSystem(SELIS)wasestablishedasavirtualinstituteinNagoyaUniversityinMarch2008,tofollowuptheresearchactivityofthe21stcenturyCOEProgramof“theSun-Earth-LifeInteractiveSystem”.ThememberinstateofSELISareHyARC,GraduateSchoolofEnvironmentalSciences(GSES),GraduateSchoolofBio-AgriculturalSciences(GSBS)andtheSolar-TerrestrialEnvironmentalLaboratory.TheSELISprojectofficeislocatedatthe5thflooroftheInstituteforAdvancedResearchHallofthiscampus,andtheHyARCismanagingthisofficeasamaininstituteofSELIS.ThemainobjectiveoftheSELISistopromotecoopearativestudiesandrelevantcapacitybuildingfortheEarth-LifeInteractionstudies,andtopromotecollaborationwithrelevantnationalandinternationalprogramsandprojects.SELISisalsoexpectedtocontributetoresearchprojectsproposedfromNagoyaUniversitytotheResearchInstituteforHumanityandNature(RIHN)inKyoto.Intheeducationprogram,SELIScontributestosomelecturecourseandseminars,e.g.,“Chikyu-gaku”(StudyfortheEarth)attheGSES. Inacademic year2010,SELISorganized seven interdisciplinary seminars.SELISalsocontributes tobasic environmental studiesandeducationunder theGlobalCOEProgram“FromEarthSystemSciencetoBasicandClinicalEnvironmentalStudies(BCES)”thatstart-edinJuly2009.InNovember,SELISco-sponsoredaninternationalworkshopon“Impactofsolar activity on climate variability and change”. Two faculty members of SELIS, with agraduate student,publishedone scientificpaper (Zhang,YasunariandOhta,2011)on theTaiga-parmafrostcoupledsysteminSiberiaanditsresponsetothefutureclimatechangeattheEnvironmentalResearchLetters(ERL),whichisaninternationally-renownedjournalontheenvironmentalsciences.
11
12 Division of Regional – Scale Water Cycle Processes
Laboratory of Meteorology
MaintenanceandenhancementmechanismsoftheprecipitationbandformedalongtheIbuki–SuzukaMountainsonSeptember2–3,2008
AheavyprecipitationeventoccurredalongtheIbuki–SuzukaMountainslocatedinthewestof theNobiPlain,JapanonSeptember2–3,2008.Themaximumtotalprecipitationamountobservedbyraingaugesfor18hwas425mm.Thiseventwascausedbyastationaryprecipitationbandthatformedalongthenorth–south-orientedmountainsandstagnatedforapproximately13hfrom12JSTonSeptember2to01JSTonSeptember3.Thelengthandwidthofthebandwereapproximately100kmand20km,respectively. AtimeseriesofhorizontalwindsinaverticalprofileobservedbyawindprofilerradarlocatedatNagoyaLocalMeteorologicalObservatoryshowninFig.1wascapturedonthewindwardsideoftheband.Thelow-levelsoutheasterlywindwaswarmandmoistwithequivalentpotential temperaturegreaterthan355Kandwasinducedbyasynopticcondition (not shown). It would impinge on theeasternslopeoftheMountainsandcontinuouslydevelopprecipitationcells.Thesecellswerepropa-gatednorthwardbysoutherlywindsaboveaheightof1km(Fig.1),correspondingtothealignmentoftheband.Themaintenanceofthebandwouldbeattributedtokeeptheverticalwindprofileforap-proximately13hthroughthesynopticcondition. Twosignificantheavyprecipitationareaswithhorizontalscalesofapproximately10kmappearedintheband.Oneoftheareaswasincludedintherangeofadual-DoppleranalysisobtainedbytwoX-bandpolarimetricDopplerradars.Thisanalysisshowthatalow-levelsoutheasterlywindataheightof1kmconvergedinawedge-shapedvalleyopeningsouthwardbetweentheIbuki-SuzukaMountainsanditsbranch,theYoroMountains,whichareorientednorth–northwesttosouth–southeast(Fig.2).Thelocationofthisvalleycorrespondstothewindwarddirectionofwarmandmoistinflow.Theprecipitationen-hancementmechanismofthisareacanbeattributedtothecontinuousupdraftsanddevelop-mentofprecipitationcellsformedbythelow-levelconvergenceoverthisvalley.
Fig. 1 Timeseriesofhorizontalwindsinaverticalpro-fileobservedfrom00JSTonSeptember2to06JSTonSeptember3,2008byawindprofilerradarlocatedatNagoyaLocalMeteorologicalObserva-tory.Fullandhalfbarbsdepict5and2.5ms–1,respectively.
Fig. 2 (a)Horizontaldistributionofreflectivityataheightof3km(shades)andhorizontalwindsat1km(arrows)at1730JSTonSeptember2,2008.Contourshowsaheightof300mabovesealevel.
(b)Verticalcrosssectionofreflectivity(shades)andwindvectorsalongtheA–Bplane(arrows)in(a).
13StructureandformationmechanismoftherainbandaroundthecenterofTyphoon0918atlandfall
Heavyrainfallproducedbylandfallingtyphoonsinteracted with the typhoon’s atmospheric environ-ment,underlyingsurfacecondition,andinternalme-soscalestructure.Althoughmanypreviousstudieshavereported the orographic effect on the heavy rainfallproducedbylandfallingtyphoons,additionalfactorshavenotbeenstudiedmuch.Typhoon0918(T0918)broughtheavyrainfalltotheKiiPeninsulaandAichiPrefecturefrom00to07JSTonOctober8,2009.Thepurposeof this study is to clarify the structureandformationmechanismoftherainbandaroundthecen-terofT0918atlandfallandstructurealterationtoanextratropicalcyclone. TheheavyrainfallareaproceedednorthwardovertheeasternslopeoftheKiiPeninsulawiththepropaga-tionofT0918from00to04JSTonOctober8.Strongeasterlywindsinthelowertropospherewereobservedinthenorthernsideofthetyphooncenterduringtheperiod.Equivalentpotentialtemperatureinthelow-leveleasterlywindwasgreaterthan350K,thusawarmandmoistairmassascendedovertheeasternslopeoftheKiiPeninsulaandbroughtheavyrainfall.Duringtheperiod,theobservedcloud-topheightwasnotsig-nificantlyhigh,andlightningwasnotobservedthroughLightningLocationSystem(LLS)operatedbyChubuElectricPowerCo.,Inc.Thefactthattheheavyrainfallwascausedbytherelativelyshallowprecipitationsys-temovertheKiiPeninsulacorrespondstoseveralpre-viousstudies. AsT0918propagatednorthward,heavyrainfallwasobservednearAichiPrefecture.Theheavyrainfallwascausedbyarainbandalignedfromsouth–southwesttonorth–northeastwhoseecho-topheightdefinedby20dBZewashigherthan12km(Fig.3).FrequentlightningwasalsoobservedbyLLSduringthepassageoftherainbandnearAichiPrefecture.Figure4showshorizontaldistributionsofreflectivityatheightsof2kmand7kmat0350,0410,and0450JSTonOctober8observedbytheDopplerradarlocatedatNagoyaLocalMeteorologicalObservatory.Thedeeprainbandobservedat0450JSTdevelopedthrough
themergingofashallowprecipitationre-gionthatformedneartheeasterncoastoftheShimaPeninsulaintoanothershallowprecipitationregionthatpropagatedovertheKiiPeninsula.Thisrainbandproceedednortheastwardandwasmaintainedbycon-vergence of a low-level warm and moistsoutheasterlywindintheeasternsideandarelativelylowequivalentpotentialtem-perature airmass with the northwesterlywind in the western side. Therefore, thestructure of the deep rainband differedfromthatoftheshallowprecipitationre-gionthatdevelopedovertheeasternslopeof the Kii Peninsula. The deep rainbandwasformedabruptlybythemergingoftwoshallowprecipitationregions.
Fig. 3 Horizontaldistributionofreflectivityataheightof2kmobservedat0442JSTonOctober8,2009byanX-bandpolarimetricradarlocatedatAnjyoCity(upper)andverticalcrosssectionofreflectivityalongtheA–Blineatthesametime(lower).
Fig. 4 Horizontaldistributionsofreflectivityatheightsof2km(upper)and7km(lower)at0350(left),0410(center),and0450(right)JSTonOctober8,2009observedbytheDopplerradarlocatedatNagoyaLocalMeteorologicalObservatory.
14RelationshipofpolarimetricparameterswithpropertiesofsolidprecipitationparticlesobservedintheHokurikudistrict,Japanduringthewinterseasonin2008–2009
Tounderstandthecharacteristicsofsolidprecipitationparticlesusingpolarimetricradars,itisfirstnecessarytoclarifytherelationshipbetweenthepropertiesoftheseparticlesandpolari-metric parameters. The purpose of this study is to examine the relationship of polarimetricparametersobtainedbyaradarandpropertiesofsolidprecipitationparticles(category,diameter,shape, and number concentration) observed by a ground-based particle-imaging system atKanazawaUniversityduringthewinterseasonin2008–2009. ThepolarimetricradarlocatedatOshimizu,IshikawaPrefecture,Japanyieldedparametersofradarreflectivity(Zh),differentialreflectivity(Zdr),specificdifferentialphase(Kdp),andcorrela-tion coefficient between horizontal and vertical polarization signals (ρhv). The ground-basedparticle-imagingsystematKanazawaUniversity locatedapproximately30kmfromthe radarrecordedphotographsofeachsolidparticleanddigitizeditbyanimage-processingtechniquetoachievetheshapeanddiameterofeachparticleandtheirnumberconcentrations.Thecomplex-ity,whichistheratioofthecircumferencelengthtothatoftheminimumarea,andnumberofholeswereusedtodetermineclassificationofparticleintosnowflakeorgraupel.Here,particleswithoutholesandwithcomplexitylessthan1.21aredefinedasgraupel,whileremainingparticlesaredefinedassnowflakes.Moreover,particlewithdiameterslessthan3mmwereexcludedfromtheanalysesbecausetheirsizemadeexaminationimpractical.Thetotalvolumeofsnowflakeandgraupelparticleswascalculatedasthesumofparticlevolumesachievedbyrotatingparticlearea.Categoryandtypicalcharacteristicsofpredominantparticlesweredeterminedin1-minintervals.Tomatchthetargetareabetweenthevolumesobtainedbybothmethods,thetargetvolumeontheradarbininthelowermostPlanPositionIndicator(PPI)scanwasprescribedthroughconsid-erationofcategory,fallvelocity,andhorizontalwinddirectionandspeed. Ourobservationperiodswere1900–2100JSTonJan13,1255–1500JSTonJan15,and2100–2130JSTonFeb16,2009.Figure5showsatimeseriesofpolarimetricparameters,number,andvolumeofeachcategoryfrom1255to1500JSTonJan15.Whenconicalorroundgraupelparticleswithdiametersfrom3to6mm(graupelperiod)werepredominantlyobserved,Zh,Zdr,Kdp,andρhvrangedfrom19.9to31.2dBZe,-0.6to-0.1dB,−0.3to−0.1°/km,and0.99to1.00,respectively.Whensnowflakeswithdiametersfrom6to15mm(snowperiod)werepredominantlyobserved,thesameparametersrangedfrom14.9to27.2dBZe,−0.5to−0.2dB,−0.2to0.3°/km,and0.99to1.00, respectively. During thegraupel period, Zh increased incorrelationwiththesameshiftinobserved particle diameters ornumberconcentrations.Inaddi-tion,Zdrdecreased(approached0dB)when thepredominantpar-ticleshapewasconical (round).Theseresultscorrespondtothoseshown in previous studies. Thelower threshold of Zh to detectgraupel should be reconsideredbecausetheminimumZhwasap-proximately20dBZeinthisstudy.Itisinterestingtonotethatduringthesnowperiod,ZdrandKdpval-ueswereclosetozero,whichil-lustrates that snowflake shapesshouldnotbeoblate;thatis,theverticalandhorizontaldiametersmatch.
Fig. 5 Timeseriesofpolarimetricparameters(upperandmiddlepanels),number,andtotalvolumeofsnow/graupelparticles(lowerpanel)observedfrom1255to1500JSTonJanuary15,2009.Zh(solidline)andZdr(brokenline)obtainedbyapolarimetricradarin5-minintervalsareshownintheupperpanel.Kdp(brokenline)andρhv(solidline)areshowninthemiddlepanel.Numberofsnowparticles(orangebargraph),graupelparticles(bluebargraph),andvolumeofsnow(brokenline)andgraupel(solidline)obtainedbytheground-basedparticle-imagingsystematevery1-minintervalsareshowninthelowerpanel.
15VerticalobservationoficeparticlesizedistributionsinastratiformregionofaMesoscaleCon-vectiveSystemduringtheBaiuperiod
Althoughmanypreviousstudiesdoc-umentedthedynamicstructureofMeso-scaleConvectiveSystems(MCSs),nore-searchisbasedonmicrophysicalinsituobservationoficeparticleswithdiame-terslessthan500µm.Weconductedanin site observation of ice particles in astratiformregionofaMCSonJune12,2008 using hydrometeor videosonde(HYVIS)atOkinawaIsland.This studyanalyzes the vertical distribution of iceparticle properties obtained by HYVISobservation, including shape, numberconcentration,andparticlesizedistribu-tions (PSDs), and discusses the iceparticlegrowingprocess. AMCSfocusedinthepresentstudydevelopedalongtheBaiufrontandprop-agatedeastwardovertheEastChinaSea.ItsstratiformregioncoveredOkinawaIsland.HYVISlaunchedat1426JSTonJune12showsthemeltinglevelataheightof4.5km.UsingimagesobtainedbyHYVIS,iceparticleswereclassifiedintosixcategoriesaccordingtotheirshape:needle,column,plate,columnandplate,aggregate,andundefined.TheverticalprofilesofnumberconcentrationsofeachcategoryandPSDswerealsoestimated. Figure6showsverticalprofilesofnumberconcentrationsofeachcategorydividedbytheirshape,whichwasdelimitedbyamaximumdiameterof100µm.Thelargestcategorywastheplatetype,whichsuggestedthattheiceparticleswereobtainedinlowsupersatura-tionconditionswithicelessthan10%.Theordersofnumberconcentrationwithdiameterssmallerorlargerthan100µmwere105m−3or104m−3,respectively.Almostundefinedcate-gorywasthesmallparticleswithdiametersrangingfrom10to20µm.NosupercooledliquidparticlesorrimediceparticlesweredetectedbyHYVIS. PSDisdefinedbyslopeparameter(Λ)andinterceptparameter(N0).PSDsateachheightwerecalculatedbyfittingontheregressioncurveoftheMarshall–Palmerdistribution.Figure7showsverticalprofilesofΛandN0calculatedusingPSDsateachheight.Thegrowthprocessoficeparticlesisassumedbytheverticalprofiles of these parameters. When theheightdecreasesbetween10and12km,between7and8km,andlessthan6km,bothΛandN0decrease.Thevariationsoftheseparametersshowadecreaseinthenumberconcentrationoficeparticlesandtheappearanceoflargeparticleswithadecrease inheight,whichsuggests thataggregationgrowthispredominant.Onthecontrary,whentheheightdecreasesbetween8and10kmandbetween6and7 km, Λ is constant and N0 increases,which suggests a predominant deposi-tionalgrowth.
Fig. 6 Verticalprofilesofnumberconcentrationsofeachcategorydividedbytheirshape(shadedbargraph),whichwasdelim-itedbyamaximumdiameterof100µm.Maximumparticlediameterlessthan100µm(left)andgreaterthanorequalto100µm(right)areshown.Solidandbrokenlinesrepresentthedegreesoficeandwaterofsaturation,respectively.
Fig. 7 VerticalprofilesofN0 (left)andΛ (right) fromthemeltinglevelatapproximately4.5km to12km.Theseparameterswere obtained by fitting on the regression curves of theMarshall-Palmerdistribution.
16CharacteristicsofprecipitationcellsobservedbyR/VMiraioverthetropicalwesternPacificOcean
Precipitation cells, which are fundamental elements of precipitation systems, requirestatisticalanalysestoclarifytheirgeneralfeatures.Thisstudyinvestigatesstatisticalcharac-teristicsofprecipitationcellsoverthetropicalwesternPacificOceanusingdatarecordedfromJune6toJune27byaship-borneDopplerradarandupper-airsoundingobservationsobtainedbyR/VMirai(MR08-02)ofJapanAgencyforMarine-EarthScienceandTechnology(JAMSTEC)at135.0E/12.0N.Theareaand30-dBZeecho-topheightofeachprecipitationcellwereanalyzedastheirhorizontalandverticalscales,respectively.Athree-dimensionaldetec-tionalgorithmdevelopedinapreviousstudydetected13,654precipitationcellsduringtheobservationperiod. Figure8showsanintegratedprobabilitydensityof30-dBZeprecipitationcellecho-topheight.Theratiooftheecho-topheightnotexceedingthemeltinglevel(4.9km)+1kmwas84%.Thefrequencyofprecipitationcellswithechotopshigherthan8kmwassubstantiallylower,whichisconsistentwiththecharacteristicsofoceaniccellsreportedinpreviousstud-ies.Figure9showstheprobabilitydensityofanareaofprecipitationcellsataheightof2kmwithanaverageandmaximumfrequencyof34.8km2and21km2,respectively,whichindicatesthatthelargestareaissmallerthantheaverage. Upper-airsoundingobservationsconductedevery3hduringstationaryobservationonR/VMiraishowachangeintheatmosphericenvironment;thatis,mid-leveldrynesswithalow-leveleasterlywindwascharacterizedintheformerperiod,andadeep,moistlayerwithalow-levelwesterlywinddevelopedinthelatter.Sensitivityofthecharacteristicsofprecipi-tationcellsonrelativehumidity(RH)atheightsof3,4,and5km;verticalgradientofequiv-alentpotentialtemperaturebetween0.5and6.0km;andconvectiveavailablepotentialen-ergy(CAPE)asindicesofatmosphericenvironmentswereexamined.Precipitationcellshavelower(higher)30-dBZeecho-topheightandsmaller(larger)areaataheightof2kminthelower(higher)RHataheightof3km.Inaddition,thosewithsmaller(larger)areaataheightof2kmcorrespondtotheatmosphericenvironmentwithlower(higher)RHatheightsof4and5kmandwithsteep(gentle)verticalgradientofequivalentpotentialtemperature.How-ever,lesssensitivitywasobservedon30-dBZeecho-topheightsinRHatheightsof4and5kmandverticalgradientsofequivalentpotentialtemperature.Moreover,lesssensitivityinprecipitationcellswasobservedforCAPEcharacteristics.
Fig. 8 Integrated probability density of 30 dBZe echo-topheightinprecipitationcellsobtainedbyaship-borneDopplerradaronR/VMirai(MR08-02).
Fig. 9 Probabilitydensityofareaofprecipitationcellsataheightof2km.
17SimulationoflightningactivityusingCReSSLightningSimulator
WesimulatedlightningactivityusingaLightningSimulatorbasedonCloudResolvingStormSimulator(CReSS).ThisLightningSimulatorfeaturestwoprocesses:accumulationofelectricchargebyhydrometeorparticlechargingandlightningdischarge.Thelightningdischargeprocess includes theextensionof lightningchannelsandchargeneutralization.Althoughtheparametersensitivitywasconfirmedinpreviousstudiesofthelightningchannelextensionprocess,uncertaintiesexistedforparametersofthechargeneutralizationprocess. Inthechargeneutralizationprocess,threeparametersareusedtoconductthesensitivityexperiment:minimumthresholdofchargedensitythatdeterminestheregionofchargeneu-tralization(ρchan);minimumthresholdofchargedensitythatremainsbehindchargeneutral-ization(ρneut);andratioofneutralization(fρ).Ifthechargedensityatacertaingrid(Qx)isgreaterthanρchan,thegridhasapossibilitytobeinlightningchannelsandneutralize.Here,theneutralizedchargedensityinthegridis(Qx-ρneut)×fρ.Thisstudyexaminessensitivityexperimentsonthethreeparametersinthechargeneutralizationprocessbycomparingfre-quenciesofcloud-to-groundlightninganditspolarityusingLLS. Figure10showstheratioofnegativepolaritycloud-to-groundlightningtoallcloud-to-groundlightningfrom2340to2350JSTonSeptember2,2008.Here,sensitivitywithvaryingfρandρchanareconfirmedwithconstantρneut.Almostsimulatedpolaritiesratiointhesesen-sitivity experiments corresponded to the observed one obtained by LLS; that is, negativepolaritywasapproximately74%.Thisresultsuggeststhatfρandρchanhavelesssensitivityonthepolarityofcloud-to-groundlightning. Anadditionalsensitivityexperimentrevealedthathighfρsignificantlydecreasedthefre-quencyofthecloud-to-groundlightning,althoughlesssensitivityforcloud-to-groundlightningfrequencywasobtainedbyvaryingρchanandρneut.Moreover,lesssensitivitywasobservedintheratioofthecloud-to-groundlightningtoalllightningincludingin-cloudlightningbyvary-ingthethreeparameters,whichsuggeststhatthechargeneutralizationprocessisnotsig-nificantlycritical for lightning simulation.Thus,wecanconfirm that it is crucial for theLightningSimulatortoreproducethunderstormdevelopmentandtheirelectricchargeac-cumulationprocess.
Fig. 10 Simulatedratioofnegativepolaritycloud-to-groundlightningtoallcloud-to-groundlightningfrom2340to2350JSTonSeptember2,2008.
Parametersfρ(horizontalaxis)andρchan(typeofline)arevariedwithconstantρneut. Observed ratio of negative polarity by LLS is approximately 74%indicatedbytheboldline.
18
Laboratory for Climate System Study
DynamicsofLarchTaiga–PermafrostCoupledSysteminSiberiaunderClimateChange Larchtaiga,alsoknownastheSiberianborealforest,playsanimportantroleinglobalandregionalwater–energy–carbon(WEC)cyclesandintheclimatesystem.Recentinsituobservationshavesuggestedthatlarch-dominatedtaigatogetherwithpermafrostbehaveasacoupledeco-climatesystemacrossthebroadborealzoneofSiberia.However,neitherfield-basedobservationsnormodelingexperimentshaveclarifiedthesynthesizeddynamicsofthissystem.Here,usinganewdynamicvegetationmodelcoupledwithapermafrostmodel,werevealtheinteractiveprocessesbetweentaigaandpermafrost.ThemodeldemonstratesthatunderthepresentclimateconditionsineasternSiberia,larchtreesmaintainpermafrostbycontrollingitsseasonalthawing,whichinturnmaintainsthetaigabyprovidingsufficientwatertolarchtrees.Theexperimentwithoutpermafrostprocessesshowedthatlarchtreescandecreaseitsbiomassandbereplacedbyaprevalenceofpineandotherspeciesthatareexposed to drier hydro-climatic conditions. In the coupled system, fire, although usuallydestructive,canpreservethe larchdominationintheforests.Climate-warmingsensitivityexperimentsshowthatthiscoupledsystemcannotbemaintainedifthetemperaturerisesabove2°C.Undertheseconditions,aforestwithtypicaldeciduousanddarkconiferborealtreespecieswouldbealternativelydominatedanddecoupledfromthepermafrostprocesses.This study thus suggests that future global warming could dramatically alter the larch-dominatedtaiga–permafrostcoupledsysteminSiberiathroughassociatedchangesinWECcyclesandfeedbacktoclimate.
Fig. 1Schematicdiagramofsoil,vegetation,andfirefeedbackintheSiberiantaiga–permafrostsystemconsideredinthisstudy(right-sidediagram);spatialdistributionoflarchtaiga(bottomleft)andboundaryofpermafrost(bottomleft,dashedlines); location(bottomleftstar)andclimateofYakutsk(topleft).Intheschematicdia-gram, arrows show forcedirectionsbetweeneach factor. Symbols “+”and “–” indicate apositive andnegativecorrelationbetweentwofactors,repectively;“±”indicatesanunclearcorrelation.Thethickerar-rowsindicateprocessesthatwerebetterconsideredinmodelsimulation.Dashedarrowindicatesaprocessnotconsideredinthisstudy.Thewordsbesideeacharrowidentifythevariablesthatcontroleachprocess.
19Reference:Zhang,N.-N.,,T.YasunariandT.Ohta.2011:Dynamicsofthelarchtaiga-permafrostcoupledsystem
inSiberiaunderclimatechange,Environ.Res.Lett.6,2,doi:10.1088/1748-9326/6/2/024003
Fig. 2 Timesequenceofsimulatedforestsuccessionandactivelayerthickness(ALT)ofpermafrost.Coloredareasindicatetheassembledsimulationofabove-groundforestsuccessionfrombareground(first300yearsof1000-yearrun);dashedlinerepresentsassembledresultofsimulatedannualmaximumALT’“+”symbolsindicate observed biomass above ground at different forest stages; pie charts show observed (left) andsimulated(right)forestcompositions.
Fig. 3 Above-groundtotalbiomassincludingfractionalcomponentsofmajorspeciesforCNTLrun(leftbar)andNPrun(rightbar)simulatedunderfivevariousclimateconditions.Thefivebargroups,fromlefttoright,representthepresentclimateconditions;temperatureconditionsof1.12°Cabovethepresent;+2.25°C,+4.5°C,and+4.5°Cplusprecipitationof20%abovethepresent.Theexperimentnamesareshownaboveeachbar.Thetwodashedlinesintheupperpartof thefigureshowchangesinsummer(JJA)meansoilwaterforCNTLandNPrunsindicatedbysquareanddiamondmarks,respectively.Notethechangesofmajorspeciescontributingtothetotalbiomassunderthevariousclimateconditions.
20Long-termvariabilityofAsiansummermonsoonanditsseasonality
Anthropogenicclimatechangeduetoincreaseingreenhousegasesandaerosolhasbecomeamajorissueinrecentdecades.Assessmentofsuchclimatechangebasedonobservationaldataandsensitivityexperimentswithclimatemodelsisstronglyrequiredforbetterunder-standingof itsprocessandmechanism. In this study,wehave investigated the long-termtrendsoftheAsiansummermonsoonrainfallandthecirculationfieldduring1979–2008onamonthlymeanbasisbyusingtherainfalldataset(CMAP),reanalysiswindcirculationdata(NCEP/NCAR),HadISST(UKMetoffice),andinterpolatedOLRdata(NOAA).Thenon-para-metricMann–Kendalltestisappliedforevaluatingthetrends.Inparticular,wefocusedontheseasonaldependenceoflong-termclimatechange. InMay,asignificantincreasingtrendofmonsoonrainfallisobservedovertheArabianSea,theBayofBengal,andtheSouthChinaSea(Fig.4a).Trendsofstrongwesterlywindappearalong10N,whichcorrespondtoenhancedconvectionwithrainfall.Incontrast,therainfallovertheabovementionedareasshowsasignificantdecreasingtrendinJune(Fig.4b).TheincreasingtrendoverSouthernChinaisalsoremarkableinJune.Theserainfalltrendsareconsistentwiththemonsooncirculationandwatervaporfluxtrendsinthelowertropo-sphere.Inaddition,weexaminedthevariabilityinmonsoononsetduring1979–2008onthebasisoftheclimatologicalpentadmeanrainfalldata.ThemonsoononsetdatedefinedbyWangandLinHo(2002)isfollowed.Inrecentdecades,themonsoononsetdatesforsoutheasternandeasternAsiahasbeenshiftedapproximatelyto10–15daysearly(Fig.5),whichreflectstherainfalltrendsinMayandJune.Interestingly,theAsianmonsoonrainfallinJulyandAugustdoesnothaveanyclearsignificanttrend.Thus,theAsianmonsoonhasasignifi-canttrendonlyduringthetransientphasefromborealspringtosummer.
Fig. 4 (a) Lineartrendofrainfall(CMAP;Shading:mm/day)and850hPawind(NCEP/NCARReanalysis;vector:m/s)inMayduring1979–2008.Allvaluesaremultipliedby30(years)fortheperiod1979–2008.Onlythosethataresignificantat95%levelbytheMann–kendalltestareplotted.
(b) SameastheLeftpanel,butforJune.
(a)
(b)
21 Itissuggestedthatthesetrendsofearlymonsoononsetarecloselyrelatedtotheincreas-ingtrendsofSSToverthetropicalPacificandIndianOceanaswellastheincreasingtrendsofthelandsurfacetemperatureintheAsiancontinent.However,theseSSTwarmingtrendslastthroughouttheyearwithlesssignificantseasonalvariations.GCMsimulationssuggeststrongseasonalityintheeffectofincreaseinanthropogenicornaturalaerosolforcingontheAsianmonsoonclimate. ThisstudyispartiallysupportedbytheresearchfundforglobalwarmingundertheMinistryofEnvironment(A0902)titled“IntegratedImpactofVegetationandAerosolChangesonAsianMonsoonClimate.”
Fig. 5 Dateofmonsoononsetobtainedbyclimatologicalpentadmeanrainfallduring1979–1993(Digit).TheonsetpentadisdeterminedasinWangandLinho(2002).TheJulianpentadinwhichtherelativerainfallratesubtractedbytheJanuarymeanexceeds5mm/dayisdefinedastheonsetpentad.Shadingdenotesthedifferencebetweenthemonsoononsetfor1994–2008and1979–1993.
22
Laboratory for Cloud and Precipitation Climatology
EquatorialAsymmetryofEastPacificinter-tropicalconvergencezone(ITCZ) ThelocationoftheeastPacificinter-tropicalconvergencezone(ITCZ),abandof area covered with convective clouds,exclusivelytothenorthoftheequator(Fig.1)hasbeenalong-standingmystery.Whilemany theories explain this north–southITCZ asymmetry, observational verifica-tion is still required. Therefore, theproposed hypotheses are quantitativelyexamined.Toachievethis,theequatorialasymmetry of the east Pacific ITCZ isexploredonthebasisofanoceansurfaceheatbudgetanalysisperformedusingvarioussatellitedataproducts. TheannualmeanclimatologyofabsorbedshortwavefluxexhibitsamarkedmeridionalasymmetrybecauseofthereductionofinsolationbyhighcloudsinthenorthITCZ.Oceanmixed-layeradvectionhasthegreatesteffectofcounteractingthisshortwave-exertedasym-metry.Althoughotherheatfluxes,inparticularlatentheatflux,predominateovertheadvec-tiveheatfluxinmagnitude,theyaresecondaryfactorswithrespecttoequatorialasymmetry(Fig.2).TheasymmetryintheadvectiveheatfluxoriginatesfromawarmpoolofftheCentralAmericancoastand,toalesserextent,theNorthEquatorialCounterCurrent,neitherofwhichexistsinthesouthernhemisphere.Theirregularcontinentalgeographypresumablycomesintoplaybygeneratingawarmpoolnorthoftheequator,andbringingcoldwatertothesouthinthefareasternPacific. Inadditiontotheannualclimatology,thenorth–southcontrastintheseasonalcycleofthesurfaceheatfluxisinstrumentalinsustainingthenorthITCZthroughouttheyear.ThenortheastPacificisexposedtoaseasonalcycleconsiderablyweakerthanthatinthesoutheastPacific.ThisiscausedbymultiplephenomenaincludingthefiniteeccentricityoftheEarth’sorbitandthemeridionalgradientinmixedlayerabsorptivity.Simpleexperimentsgeneratingsyntheticseasurfacetemperature(SST)illus-tratethatthemutedseasonalcycleofheatfluxforcingmoderatesSSTseasonalvariability inthenortheastPacific, thusallowingthenorthITCZtosustainthroughouttheyear. Existing theories on the ITCZ asymmetryare briefly examined considering the presentfindings:1)Thewind-evaporative-SST(WES)feedbackisactivebutconsiderablyweaktoen-tirely cause the equatorial asymmetry; 2) thestratus-SSTfeedbackisalocalizedeffectneartheSouthAmericancoast;and3)theupwelling-SSTfeedbackislimitedtotheequatorialcoldtongue and is unlikely to help maintain theITCZ.
Fig. 2 North–southcontrastinzonal-meanheatfluxes:absorbed shortwave (shaded), latent heat(solid),upwelling(dotted),longwave(dashed),andadvectiveheat(dot-dashed).
Fig. 1 Geographicalmapofannualmeandeepconvectivecloudcover(shaded)andSST(contour).
23SatelliteStudyofAtmosphericForcingandResponsetoMoistConvectionoverTropicalandSubtropicalOceans
Tropicalconvectivecloudsareoftendescribedas“mediators”actingagainstlarge-scaleforcingthatdestabilizestheatmosphere,suchasmoisturecon-vergence and surface heat flux. This neutralizingeffectofconvectionwasformulatedbyDrs.AarakawaandSchubertintothequasi-equilibriumhypothesis,whichhasbeenwidelyacceptedasthebasisformanycumulusparameterization schemes.On theotherhand,somerecentstudiesdiscoveredobservationalevidence that necessitates updating the quasi-equilibriumhypothesisasoriginallypostulated. Satellitedataareanalyzedtoexplorethether-modynamicevolutionoftropicalandsubtropicalatmospherespriorandsubsequenttomoistconvec-tioninordertoofferanobservationaltestbedforconvectiveadjustment,whichisimportanttothequasi-equilibriumhypothesis.MeasurementsbytheTropicalRainfallMeasuringMission(TRMM)andAquasatellitesareprojectedonacompositetem-poralsequenceoveranhourlytodailytimescale.Thisisdonebyexploitingthetemporalgapbetweenthelocalsatelliteoverpassesthatchangesdaily(Fig.3).Theatmosphericforcingandresponsetoconvectionareinvestigatedseparatelyfordeepconvectiveandcongestusclouds.ConvectiveadjustmentisquickandefficientinthedeepTropicsduringtimeswhendeepconvectionisactive.Moisturetransportfromtheatmosphericboundarylayer(ABL)tothefreetroposphereisevidentinassociationwithdeepconvection.However,theevolutionofconvectiveavailablepotentialenergy(CAPE)iscontrollednotonlybyABLmoisturebutalsoextensivelybycoin-cidentABLcooling.CAPEexhibitsarapiddropfor12hpriortoconvectionandasubsequentrestoringphaselasting1–2daysasthecoolanomalyrecovers(Fig4a).ABLcoolingisaccom-panied180°outofphasebymid-toupper-troposphericwarmingtogethercomprisingabipo-lartemperatureanomaly.ThebehaviorofCAPEisconsiderablydifferentwhenmoistconvec-tioniscausedbycongestuscloudswithnodeepconvectionnearby.CAPEgentlyincreasesoverape-riodof1–2daysuntilcongestusclouds appear, then slowly de-clinestotheinitiallevel(Fig.4b).Convectiveadjustmentisnotef-ficientlyatworkeveninthedeepTropics when convective cloudsarenotdevelopedsodeepinorderto penetrate the entire tropo-sphere. The subtropical atmo-sphereshowsnosignofconvec-tiveadjustment regardlesof thepresenceofvigorousconvection.
Fig. 3 Schematic representation of compositeanalysis.TRMMandAquaobservationsaremarkedbycloudsandlinegraphs,respec-tively.
Fig. 4 CompositeCAPEfordeepconvection(a)andcongestusclouds(b).
24 Division of global – Scale Water Cycle Variations
Loboratory of Satellite Meteorology
DualKa-bandradarsystemobservationforthefutureGlobalPrecipitationMeasurementMission AdualKa-bandradarsystemwasdevelopedbytheJapanAerospaceExplorationAgency(JAXA)fordevelopingtheglobalprecipitationmeasurement–dual-frequencyprecipitationradar(GPM–DPR)algorithm.ThedualKa-radar system,whichconsistsof two identicalKa-bandradars,canmeasurespecificattenuationandequivalentradarreflectivityattheKaband;boththeseparametersareimportant,particularlyforsnowmeasurement.UsingthisdualKa-radarsystem along with other instruments such as ground-based rain measurement systems andpolarimetricprecipitationandwindprofilerradars,parameteruncertaintiesintheDPRalgorithmcanbereduced.VerificationofimprovementinrainretrievalusingtheDPRalgorithmisalsoincludedasanobjective. Thebasicconceptofthemeasurementistocomparethesameprecipitationsystemintworadarsplaced10–20kmapart.Thebeamofthefirstradarisdirectedtomatchthatofthesecondradar.Ingeneral,theprecipitationechointensitydecreaseswithrangebecauseofrainattenua-tion,whichappearssymmetricallyinbothradars.Throughthismethod,theseparationofequiv-alentradarreflectvitivyofprecipitationandrainattenuationcanbeattained. ThedualKa-bandradarsystemisinstalledattheOkinawaSubtropicalEnvironmentRemoteSensingCenter,theNationalInstituteofInformationandCommunicationsTechnology(NICT),wheresimultaneousobservationofrainwithaC-bandpolarimetricDopplerradarandgroundrainobservationinstrumentsiscurrentlyunderway.Thisradarisafrequencymodulatedcon-tinuouswave(FMCW)systemwitharelativelylowtransmittingpowerof100Wandtwooffsetparabolicantennasthatenablesimultaneoustransmissionandreception.Thissystemishighlydigitizedwithflexibilitytoadjustsystemparameterswithobservationsandisequippedwiththreeobservationmodes:(1)nominal,witha15kmobservationrangeand50mrangeresolu-tion;(2)long-range,witha30kmobservationrange;and(3)high-sensitivity,with250mrangeresolution. Figure1showstheobservationconfigurationinOkinawaIsland.Thetworadarbeamsarenotanexactmatchbecauseoftheinterferencecausedbyasmallmountainthatexistsbetweenthetworadars.Nearthemiddlepoint,instrumentsareinstalledtomeasuregroundrain.Figure2showsanexampleoftheprecipitationechoesrecordedbythetwoKa-bandradarsonJanuary15,2011.Thetwopatternsappearsymmetricalbecausebothradarsobserveprecipitationin
Fig. 2 PrecipitationechoesobtainedfromdualKa-radarsystem.
Fig. 1ConfigurationofdualKa-radarsystemobservation.
25oppositedirections.StrongrainattenuationintheKabandcausesastrongechonearoneradarandaratherweakdetectionnearthesecond.ThisfiguresuggeststhefeasibilityofspecificrainattenuationestimatesobtainedfromthisdualKa-bandradarsystem.
StudyofKuroshio’simpactonprecipitatonusingsatellitedata TheKuroshioisawarmcurentwiththeseasurfacetemperature(SST)warmerthanthatofthesurroundingoceanthroughouttheyear.PrecipitationgenerallyoccursoverwarmSSTareasasaresultofincreasedwater-vaporandsensible-heatfluxesfromtheseasurface.Inthisstudy,theKuroshio’sinfluenceonprecipitationisinvestigatedusingtheGlobalSatelliteMappingofPrecipitation_MVK+(GSMaP_MVK+)productanddataobtainedfromprecipita-tion radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. TheprecipitationbandalongtheKuroshioappearsafteraveragingGSMaP_MVK+for2003–2006.ToidentifythetypeofprecipitationsystemmostoftenattributedtotheKuroshio,GSMaP_MVK+dataaredividedintoseveraltypesaccordingtosynopticscaledisturbances.Compos-iteanalysis reveals that rainappears tobeenhancedby theKuroshioand that thisbandmainly consists of precipitation associated with atmospheric fronts. Little precipitationappearsduringcold-airoutbreaksdespitethestrongatmosphere–oceancontrastintempera-tures. PRdataprovidevariousprecipitationdetailsincludingconvectiveorstratiformprecipita-tiontypes,stormheight,andtheverticalprecipitationprofile,inadditiontonearsurfacerainrate,whichallowustostudyprecipitationcharacteristicsingreaterdetail.Thisanalysisre-vealsthattheKuroshioplaysamoresignificantroleinthefrequencyofconvectiveprecipita-tionthanthatofprecipitationintensityforconvectiveorstratiformpreciptation(Figs.3and4).ThefrequencyofconvectionateachaltitudeisinvestigatedtoobservethescopeoftheKuroshio’seffect,whichispresentupto9kmanddisappearsat10km.Aninterstingfeatureis that thestormheightovertheKuroshioappears lower inthewinter.ThesurfacewindvelocityisalsohigheroverorslightlynorthwestoftheKuroshio,whichcanbeexplainedbyverticalmixing.However, therapidsurfacewindareadoesnotexactlycorrespond to thelowerstormheightregion.
Fig. 4 Distributionofconvectiverainfrequency.
Fig. 3LocationoftheKuroshio.
26
Laboratory of Satellite Biological Oceanography
SeasonalandSpringInterannualVariationsofChlorophyll-aintheYellowSeaandEastChinaSeaUsingaNewSatelliteDataSetwithReducedInfluenceofSuspendedSediment
IncreaseinredtideandmassiveoutbreakofgiantjellyfishareknownproblemsintheYellowSeaandEastChinaSea(YECS).Itisspeculatedthateutrophicationisoneoftheirpossiblecauses.TheoccurrencesindicatedthattheenvironmentalconditionsinYECSmaybechanging.Furthermore,theconstructionofThreeGorgesDamintheupperstreamofChangjiangRiverissuspectedofinfluencingtheenvironmentoftheYECS.Oceancolorremotesensingdataaccu-mulatedovermorethan10-years,whichcanmeasuresurfacechlorophyll-a(Chl)asanindexoftheamountofphytoplankton,isagoodtoolforexamininginterannualvariationsofChlintheYECS.However,itissuggestedthattheaccuracyofthestandardsatelliteChl(standardSCHL)ispoorbecauseofthehighconcentrationofsuspendedsedimentintheYECS.Inthisstudy,anewSCHLalgorithm,withreducedinfluenceofsuspendedsediment,hasbeendeveloped,andtheseasonalandspringinterannualvariationsofnewSCHLwasexaminedwithcomparingsatellite-estimatedtotalsuspendedmatter(TSM)intheYECS. ThemonthlynewSCHLwaslowerthanthestandardSCHLatcoastalareasandaroundtheChangjiangHillock,wherethebottomtopographyisshallow(<50m),fromfalltoearlyspring.Insummer,theareaofthelowernewSCHLwaslimitedalongthecoast.TheselowernewSCHLareascorrespondedtohighTSMareas. TSMwaslowthroughouttheyearinthemiddleofYellowSeaandsouthoffthehillock,andmaximumSCHLwasobservedinApril(Figs.1bandb).Itisconsideredthatspringbloomsoccurredintheseareas.CorrelationbetweenSCHLandTSMwashigh,andtheratioofSCHLinTSMwashigh.ThisindicatedthatvariationofTSMmostlydependedonconcentrationofphytoplanktonandthatinorganicmatterintheTSMwaslowattheseareas(Figs.2aandb).
Fig. 1 Seasonal variation of monthly newSCHL (black circle) and TSM (whitecircle)averagedover10-yearsineacharea.(a)middleofYellowSea,(b)southoffChangjiangHillock,(c)offshoreofChangjiangRivermouth, (d)Changji-angHillock,and(e)eastoffChangjiangHillock.
Fig. 2 Scatter diagram of 10-year averagedmonthlynewSCHLandTSMineacharea.(a)middleofYellowSea,(b)southoffChangjiangHillock,(c)offshoreofChangjiangRivermouth, (d)Changji-angHillock,and(e)eastoffChangjiangHillock. Lines indicate the regressionlineatthemiddleofYellowSea.
27 Ontheotherhand,onthehillockthemonthlySCHLwaslowwithhighTSMinwinterandincreasedwithdecreaseofTSMstartingfromApril,andmaximumofSCHLwasobservedinMay(Fig.1d).ItisconsideredthatspringbloomsoccurredfollowingdecreaseoftheTSMbecausegrowthofphytoplanktonmaybelimitedbylowlightconditionsduetothehighTSMinthatarea.Insummer,maximumSCHLwasobservedandwasprobablyduetotheinfluenceofChangji-angDilutedWater.Inaddition,theratioofSCHLinTSMwasashighasthatinthemiddleofYellowSeaandsouthoffthehillock(Fig.2d).Atoffshoreofthemouth,themonthlySCHLwaslowwithhighTSMinwinteranditincreasedwithdecreaseofTSMinspring.However,maximumSCHLwasnotobserved,andmaximumSCHLwasobservedinsummerandtheratioofSCHLinTSMwasashighasthatinthemiddleofYellowSeaandsouthoffthehillock(Figs.1cand2c) SpringSCHLsignificantly increasedatoffshoreof themouth,andthe increasemightcorrespondtotheincreaseintheoccurrenceandmagnitudeofredtides.InthemiddleofYellowSea,springmaximumofSCHLgraduallyincreasedsignificantly,anditseemstobecausedbyeutrophication. FromthenewSCHLandTSMdata,itisclearthatspringbloomsoccurredatthehighTSMareasaswellaslowTSMareasasaresultoffavorablelightconditionsduetodecreaseofTSM.TheincreasingtrendofthespringSCHLaswellassummerinthemiddleofYellowSeaindicatesthepossibilityofeutrophication.
ModificationofVerticallyGeneralizedProductionModelforTurbidWatersofAriakeBay,South-westernJapan
Remotely-sensedoceancolorcannotprovideadequateinformationaboutoceanicprimaryproductivity(PP)withoutthesupportofmodelsandseatruthdata.SeveralmodelsarebeingusedforderivingPPintheocean.Theverticallygeneralizedproductionmodel(VGPM)formu-latedbyBehrenfeldandFalkowski(1997a;henceforthBF)isoneofthesimplestandmostcom-monlyusedmodels forestimatingPPfromsatellite-basedchlorophylla (Chla), seasurfacetemperature(SST)andphotosyntheticallyactiveradiation(PAR)data.Despiteofconsiderableunderstandingofthephotosyntheticprocessandknowledgeoftheoceanopticsthatdetermineoceancolorsignals,satellite-basedPPoftenhave limited success in reproducing theobservedvariabilityofPPdataspecificallyin coastal environments. This study at-temptstodevelopamodifiedversionoftheVGPMforaturbidcoastalwater. TheVGPM,basicallydesignedforopenoceanwaters,wasevaluatedwithinsitumeasurementsofPPintheturbidcoastalwaters of Ariake Bay. The VGPM-basedeuphoticdepth(Zeu)-integratedPP(IPP)significantlyoverestimated(x1-3)usinginsituChlaandSST,anditexplainedonly52%oftheobservedvariability(Fig.3a).This largeerrorcouldbepartlybecausetheestimatesfromthesub-modelsforZeuand optimal Chl a-normalized PP (PB
opt)suggestedbyBFoverestimateandshowedweak correlations with in situ data. BysubstitutingPB
optandZeuwithinsituvalues;the modeled IPP significantly improvedaccounting84%ofvariabilityandshowedlessoverestimation(Fig.3b).
Fig. 3 ScatterplotsofinsituandVGPM-basedIPPobtainedbyusing(a)modeledPB
optandZeu,(b)insituPBoptand
Zeu,(c)insituPBoptandmodeledZeu,and(d)modified
VGPMmodel.Thesolidanddottedlinerepresentstheregressionlineandthe1:1line,respectively.
28 TheZeuwasthemostimportantparameterinfluencingthemodeledIPPvariationinAriakeBay.BFsuggestedopenoceanZeumodelbasedonsurfaceChla,largelyoverestimated(x2-3)(Fig.3c).AbetterestimationofZeuinthisturbidwatercouldbeobtainedfrominsituremotesensingreflectance(Rrs)byemployingaquasi-analyticalalgorithm(QAA).Amongtheparam-etersofthePPmodels,PB
optisconsideredtobethemostimportant.However,inthisstudy,PB
optwasfoundtobeofsecondaryimportanceandwasdifficulttobeestimatedfromSST.TheestimationofChlawasimprovedbyoptimizingacoastalalgorithmwithinsituRrsdata. By incorporating the QAA-based Zeu, optimizing algorithm Chl a and using constant(median)PB
opt;theperformanceofVGPMwassignificantlyimprovedinthestudyarea(Fig.3d).Thus,althoughVGPMisaglobalopenoceanmodel,whencoupledwithturbidwateralgo-rithmsforZeuandChla,itprovidedrealisticestimatesofIPPintheturbidwaterecosystem.
PhotoadaptiveResponseofPhytoplanktontoLightVariationCausedbyWindandTide:ACaseStudyofTurbidAriakeBay
Intheocean,lightisoneofthemostimportantvariablescontrollingprimaryproduction.Tomaintainhighphotosyntheticefficiencyinavariablelightenvironment,phytoplanktoncellsareknowntorespondtothevariationsoflight.ThisstudyexaminestheinfluenceoftemporallightvariationscausedbyverticalmixingonphotosyntheticpigmentandefficiencyinAriakeBay,Japan.AriakeBayisknownforitshighturbiditycausedbythelargetidalam-plitude,anditcouldbeasuitablesiteforexaminingtheinfluenceofthelightvariationsonphytoplankton.Changesofphotosyntheticpigmentandtheassociatedphotosyntheticeffi-ciencyofphytoplanktonundervaryinglightconditionswereexaminedunderatdifferenttimescalesoftheverticalmixingcausedbywindandtide. ObservationswereconductedbyT/VKakuyoMaruofNagasakiUniversityonNovember8(Cruise1)and15(Cruise2),2008andNovember8(Cruise3)and15(Cruise4),2009.Thetimescaleoflightvariationsforphytoplanktonwasevaluatedbyverticalmixingtimecoveringtheeuphoticzone(teu)estimatedbythediffusioncoefficient(Kz)andtheeuphoticzonedepth(Zeu).
Z2euteu=
2×Kz×602
Effectsofdifferenttimescalesoflightvariationsonmeanchlorophylla(Chla)-specificdiadinoxanthin(DD)anddiato-xanthin(DT)poolsize[(DD+DT)/Chla]andonmaximumquantumyieldofpho-tosystem(PS)II(Fv/Fm)wereexamined. Theshortest(4h)andlongest(27d)teuwereobservedathigh(8.6±0.5ms–1)andlow(2.2±0.8ms–1)windspeedsdur-ingCruises1and3,respectively.Despiteoflowwindspeed,theintermediatevalues(10hours)ofteuwerealsofoundasare-sultsofshallowerZeucausedbythetidalcurrent mixing during Cruises 2 and 4.(DD+DT)/Chlavariedwithdiurnalcycleand the average was higher for long teu(>10h)comparedwiththatforshortteu(<5h)(Fig.4).Theseresultsindicatedthatphoto-protective response could be ac-tivelyoccurredduringthelongestteu.TheFv/Fminupperlayerswashigherduringlongteu(>10h)comparedwiththatduring
Fig. 4 Timevariationof(DD+DT)/ChlaandPhotosyntheticallyActiveRadiation(PAR)forCruise1(a),Cruise2(b),Cruise3(c)andCruise4(d).Openedrhombussymbolsrepresentphytoplank-tonat thesurface.Openedcycleandclosedcyclesymbolsrepresenttheincubatedphytoplanktonunderhighlightcondi-tion(100%PAR)andlowlightcondition(1%PAR),respec-tively.Thinlinesrepresent1minute-averagedincidentPAR.
29shortteu(<5h).Theseresultsindicatedthatphoto-damagetotheFv/Fmunderhighlightcondi-tionswascausedbyaninactivephoto-protectiveresponseduringshortteu(<5h). Therefore,thevariationintheshorttimescale(teu<5h)inthelightenvironmentduetostrongwindmayinhibitthephoto-protectiveresponseandthephotosynthesisofphytoplank-ton.Tounderstandtheprimaryproduction,itisnecessarytoexaminehowphotosynthesischangeswithshorttimelightvariationscausedbywind.
VariationsofPhytoplanktonPhoto-physiologyandProductivityinaDynamicEutrophicEcosystem Incoastalwatersrelativelyhighprimaryproduc-tionoccursasaresultofthesupplyofnutrientsfromland.Localproductivityusuallyshowsalarge,com-plexvariationsinbothtemporalandspatialscalesinresponsetochangesintheavailabilityofresourc-es(lightandnutrients)duetotidalmovementsandthe inflowof freshwater. Inparticular,underan-thropogenicallyeutrophicconditionswithtypicallythinopticallayersduetoastrongattenuation,cellsundergopronounced,short-termchangesinalightenvironment due to vertical mixing. Therefore, astrategytoacclimatizetoagivenlightregimeiscru-ciallyimportantfortheirgrowthandsuccess.Inthisstudy, using a fast repetition rate fluorometer(FRRF),weinvestigatedthephoto-acclimationstateofphytoplanktonassemblagesandtheproductivityin the upper Gulf of Thailand (UGOT) which ishighlyeutrophiedduetoanthropogenicloading. Two onboard observations on November 2005andJuly2006revealed theregionaldifferences inthephotosystem(PS)IIparameters,FV/FM,σPSIIandthemaximumratesofQareoxidation(1/τQA).Inpar-ticular,theprofilesof1/τQAapparentlyreflectedtheregional differences in water column structures,which corresponded to the photoacclimation re-sponse. These PS II parameterswereused to estimate normalizedproductivity (PB)with aphotosyntheticmodel,andfrominsituPBprofiles;inaddition,thephotosynthesis-irradiance(P-E)curvesandtheinstantaneouseuphoticzone(EZ)-averagedPB(PB
EZ)weredetermined.ThederivedP-EparametersshowedlargedifferencesbetweentheupperstratifiedwatersinStn.1andwell-mixedwatercolumnofStn.5;ahigherαwasfoundinStn.5whilePB
maxandtheEkwerehigherintheStn.1(Fig.5;Table1).Thisindicatedthatrelativelyhighlight-acclimated(oradapted)cellsweredominantinStn.1,wheretheyweresustainedunderbrighterconditionsduetoastronghalocline.Ontheotherhand,cellsinStn.5hadacclimatedtoalowerlightlevelasaresultofdeepermixing.Asignificant(logarithmic)relationshipwasfoundbetweenPB
EZandthesurfacePARfromthedataforallprofilesdata,whichsuggestedthatthecolumnproductivityintheUGOTwasprincipallycontrolledbylightavailability.Inaddition,this implied that, although cells wereexposedtodifferent lightregimesunderlessnutrient-stress,cellsatdifferentsitesmight achieve a comparable potentialproductivity due to adequate photo-acclimation.
Fig. 5 Relationships between underwater PARandinstantaneousFRRF_basedPB(a)forStn.1,(b)forStn.5intheupperGulfofThailand.
table 1 TheestimatedP-EparametersforStn.1and5.
30
Laboratory of Bio-Physical Oceanography
StudyoftheKuroshioaxismovementassociatedwithtyphoonpassagebyusingatmosphere–oceancoupledmodel
WereproducedoceanicandmetrologicalstatesaroundTaiwanbeforeandafterTyphoonHaitang’spassagein2005forinvestigatingthemechanismoftheKuroshioaxismovement,whichwasobservedbylong-rangeoceanradar(LROR)developedbytheNationalInstituteofInforma-tionandCommunicationsTechnology(NICT),Japan.WeusedtheCloudResolvingStormSim-ulator(CReSS)developedbyTsubokiandSakakibara(2002)asameteorologicalmodelandtheNonhydrostaticOceanmodelforEarthSimulator(NHOES)developedbyAikiandYamagata(2004)asanoceanmodel,andcoupledboththemodels.Thehorizontalgridsizeofboththemodelswas0.04°,andtheverticallayersweredividedinto100layersbytheNHOESwithdepthsrangingfrom2mto100mbelowthesurface.Thecalculationperiodwas10daysfrom0:00UTCJuly14,2005,thedaywhenTyphoonHaitangspawned,to0:00UTCJuly24,2005;TyphoonHaitangmadelandfallonJuly18,2005.Thecalculatedpathofthetyphoonwasconsistentwiththatoftheobservedpath.ThemodelwindatYonaguniIslandwasslightlystrongerthantheoneobserved;however,thevariationtendencywasnearlyidentical.TheKuroshioflowednortheast-wardalongtheshelfedgeinthemodelbeforethetyphoonapproached,asobservedbyLROR(Fig.1aandb).Southerlywindassociatedwiththetyphoon’sapproachdominatednortheastTaiwanforonedayuntiltheKuroshioaxischangedthewinddirectiontonortherly.Themodelcurrentpatternat1:00UTCJuly21coincideswellwiththatoftheLROR(Fig.1candd). Volumetransportacrosstheshelfedgeincreasedby4Svwhenthewinddirectionchangedfromnortherlytosoutherlyandthenananti-cycloniceddyemergedontheshelf.Thegenerationofananti-cycloniceddyisconsideredsuchthatthewatercolumnobtainednegativevorticityasaresultofconservationofpotentialvorticitycausedbythemovementoftheKuroshiowatersfromdeeptoshallowerarea.Becausethevolumetransportacrosstheshelfedgeincreasedperi-odicallyaftertheeddyformation,negativevorticitycouldbesuppliedcontinuously.Itis,therefore,suggestedthattheanti-cycloniceddiesontheshelfcausedthechangeinKuroshioaxisdirection.
MeanfieldandseasonalvariationofseasurfacecurrentintheEastChinaSea Weobtaineddetailed,high-resolutionspatiotemporalinformationoftheseasurfacecurrentfieldintheEastChinaSea(ECS)bycombiningsatellitealtimeterandsurfacedrifterdata,andinvestigateditstemporalmeanfieldandseasonalvariationbyanalyzingthisdata. TheKuroshio’snortheastwardcurrentwithspeedsgreaterthan50cms−1alongthecontinentalshelfslope;theTaiwanWarmCurrentflowingnorthwardwithspeedsof20–30cms−1,extendingfromTaiwanStraitwithanorthwardintrusion(~30cms−1)northeastofTaiwan;andtheKuroshio
Fig. 1 Surfacecurrentfieldbeforetyphoonpassage:(a)calculatedbythemodel;(b)observedbyLROR.Surfacecurrentfieldaftertyphoonpassage:(c)calcu-latedby themodel; (d)observedbyLROR.
31branch’snorthwardcurrentwithspeedsof10–20cms−1westofKyushuweresteady(Fig.2a).Ontheotherhand,anannualvariationcausedbythedevelopmentoftwodifferentdisturbances,whichpropagatedalongtheisobathsonthecontinentalshelffromthenortheastTaiwanStraitandneartheTsushimaStrait(TS)towestofKyushu,waspredominant in the seasonal disturbance. Thespatiotemporalscaleandthepropagationofthesedisturbancescanbeexplainedbythedispersionrelationship of barotropic topographic Rossbywavespropagatinginasteadyflow.Thesedistur-bances also caused differences in the annualvariationsofcurrentspeedandaxialpositionoftheKuroshiobranchbetweenitssouthernandnorthern(linesSandNinFig.2a,respectively)parts(Fig.2bandc). Insummary,theannualvariationwaspredominantintheseasonaldisturbanceofthesurfacecurrentfield.Thisannualvariationwascausedbythepropagationofthedisturbance,whichbehavedliketopographicwavesinasteadyflowfromthevicinityofthetwostraits.Thesea-sonalvariationwestofKyushuwasespeciallyinfluencedbythesepropagationsintheECS.
TsushimawarmcurrentpathsinthesouthwesternpartoftheJapanSea TheTsushimaWarmCurrent (TWC)pathshavebeenpreviously investigatedbynumerousoceanographers;however,thecorrectcurrentpathswereunclear.Inthepresentstudy,wecreatedseasurfacecurrentanddynamicalheightfieldinformationusingsatellitealtimeterandArgosbuoytrajectorydatarecordedfromMay1995toJanuary2009.WethencomparedourseasurfacecurrentdatawithgeostrophiccurrentcomponentsoftheArgosbuoytrajectoriestoreproduceandevaluatetheaccuracyofourdataset.WeexaminedtheTWCpathsinthesouthwesternpartoftheSeaofJapan/EastSea,whereTWCpathsdisplayhighvariability,usingthedataset. Inthemeanseasurfacecurrentfield,thefirstbranchoftheTWC(FBTWC)throughtheeast-ernchannelofTSflowsalongtheJapanesecoastandthroughnorthofMishimaIsland.ThesecondbranchoftheTWC(SBTWC)flowsalongthecontinentalshelfedge,andthethirdbranchoftheTWC(TBTWC)throughthewesternchannelofTSflowsnorthwardalongtheKoreancoast. WeexaminedseasonalvariationintheTWCpaths.ItisclearthattheFBTWCandTBTWCexistthroughouttheyearwithspeedsgreaterthan15cms−1.TheSBTWCappearsinAugust,continuingthroughOctober.Inothermonths,theSBTWCflowsalongthecontinentalshelfedgewithasmallcurrentvelocity.Twocurrentaxesarepresentnearshoreandoffshoreofthecontinentalshelfeastof131°Ethroughouttheyear.TheoffshorecurrentpathappearsfromApriltoSeptember.ItisconsideredthatthiscurrentaxisoriginatedfromtheSBTWCandFBTWC,whichcouldhavebeenbifur-catedafterpassingnorthofMishimaIsland.Thenear-shorecurrentflowsthroughthewestsideofOkiwithameancurrentspeedof20cms−1,andthecurrentwithaspeedgreaterthan15cms−1appearsfromJanuarytoMayandfromAugusttoDecember. OurschematicviewoftheTWCpathsinthesouth-westernpartoftheSeaofJapan/EastSea,showninFig.3,isthefirstofitstypetobedocumented.
Fig. 2 Horizontaldistributionoftemporalmeansurfacecurrentvectors from May 1995 to January 2010: (a) annualvariationinnorthwardsurfacecurrentsalong(b)linesSand(c)N.Shadedareasin(b)and(c)representcurrentspeedwithvaluesgreaterthan15cms−1.Contourin-tervalsfornorthwardsurfacecurrentare1cms−1.
Fig. 3 SchematicviewofTsushimaWarmCurrentpathsinthesouthwesternpartoftheSeaofJapananalyzedfromMay1995toJanuary2009.
32 List of Publications*:Staffs,studentsandresearchfellowsintheHyARC.
01. Akter,N.*andK.Tsuboki* CharacteristicsofsupercellsintherainbandofnumericallysimulatedCycloneSidr.Scientific
OnlineLettersontheAtmosphere(SOLA),6A,25-28,doi:10.2151/sola.6A-007,2010.02. Bhatt,B.C.,T.-Y.Koh,M.YamamotoandK.Nakamura* ThediurnalcycleofconvectiveactivityoverSouthAsiaasdiagnosedfromMETEOSAT-5and
TRMM data. Terrestrial, Atmospheric and Oceanic Sciences, 21(5), 841-854, doi:10.3319/TAO.2010.02.04.01(A),2010.
03. Hossen,M.S.,T.HiyamaandH.Tanaka* EstimationofnighttimeecosystemrespirationoverapaddyfieldinChina.BiogeosciencesDiscus-
sions,7(1),1201-1232,doi:10.5194/bgd-7-1201-2010,2010.04. Hutahaean,A.A.*,J.Ishizaka*,A.Morimoto*,J.Kanda,N.HorimotoandT.Saino Developmentofalgorithmsforestimatingtheseasonalnitrateprofilesintheupperwatercolumn
oftheSagamiBay,Japan.Lamer,48(2),71-86,2010.05. Islam,M.N.,S.DasandH.Uyeda* CalibrationofTRMMderivedrainfalloverNepalduring1998-2007.TheOpenAtmosphericSci-
enceJournal,4,12-23,doi:10.2174/1874282301004010012,2010.06. Karev,A.R.,D.-I.Lee,C.-H.YouandH.Uyeda* Variationsinraindropsizedistributionsobservedinmid-latitudeoceancloudsduringtheEast-
Asiansummermonsoon.AtmosphericResearch,96(1),65-78,doi:10.1016/j.atmosres.2009.11.014,2010.
07. Lee,K.-O.,S.Shimizu,M.Maki,C.-H.You,H.Uyeda*andD.-I.Lee Enhancementmechanismofthe30June2006precipitationsystemobservedoverthenorthwest-
ernslopeofMt.Halla,JejuIsland,Korea.AtmosphericResearch,97(3),343-358,doi:10.1016/j.atmosres.2010.04.008,2010.
08. Li,X.,W.-K.Tao,T.Matsui,C.LiuandH.Masunaga* ImprovingaspectralbinmicrophysicalschemeusingTRMMsatelliteobservations.Quarterly
JournaloftheRoyalMeteorologicalSociety,136(647),382-399,doi:10.1002/qj.569,2010.09. Ma,X.,Y.Fukushima,T.Yasunari*,M.Matsuoka,Y.Sato,F.KimuraandH.Zheng ExaminationofthewaterbudgetinupstreamandmidstreamregionsoftheYellowRiver,China.
HydrologicalProcesses,24(5),618-630,doi:10.1002/hyp.7556,2010.10. Masunaga,H.*,T.Matsui,W.-K.Tao,A.Y.Hou,C.D.Kummerow,T.Nakajima,P.Bauer,W.S.
Olson,M.SekiguchiandT.Y.Nakajima SatelliteDataSimulatorUnit:Amultisensor,multispectralsatellitesimulatorpackage.Bulletin
of theAmericanMeteorologicalSociety,91(12),1625-1632,doi:10.1175/2010BAMS2809.1,2010.
11. Masunaga,H.*andT.S.L’Ecuyer The southeast Pacific warm band and double ITCZ. Journal of Climate, 23(5), 1189-1208,
doi:10.1175/2009JCLI3124.1,2010.12. Minda,H.*,F.A.Furuzawa*,S.SatohandK.Nakamura* ConvectiveboundarylayeraboveasubtropicalislandobservedbyC-bandradarandinterpreta-
tionusingacloudresolvingmodel.JournaloftheMeteorologicalSocietyofJapan,88(3),285-312,doi:10.2151/jmsj.2010-303,2010.
13. Oue,M.*,H.Uyeda*andY.Shusse TwotypesofprecipitationparticledistributioninconvectivecellsaccompanyingaBaiufrontal
rainband around Okinawa Island, Japan. Journal of Geophysical Research, 115, D02201,doi:10.1029/2009JD011957,2010.
14. Rafiuddin,M.,H.Uyeda*andM.N.Islam CharacteristicsofmonsoonprecipitationsystemsinandaroundBangladesh.InternationalJour-
nalofClimatology,30(7),1042-1055,doi:10.1002/joc.1949,2010.15. Saba,V.S.,M.A.M.Friedrichs,D.Antoine,R.A.Armstrong,I.Asanuma,M.J.Behrenfeld,A.M.
Ciotti,M.Dowell,N.Hoepffner,K.J.W.Hyde,J. Ishizaka*,T.Kameda,J.Marra,F.Mélin,A.Morel,J.O’Reilly,M.Scardi,W.O.SmithJr.,T.J.Smyth,S.Tang,J.Uitz,K.WatersandT.K.Westberry
Anevaluationofoceancolormodelestimatesofmarineprimaryproductivity incoastaland
33pelagicregionsacrosstheglobe.BiogeosciencesDiscussions,7(5),6749-6788,doi:10.5194/bgd-7-6749-2010,2010.
16. Saba,V.S.,M.A.M.Friedrichs,M.-E.Carr,D.Antoine,R.A.Armstrong,I.Asanuma,O.Aumont,N.R.Bates,M.J.Behrenfeld,V.Bennington,L.Bopp,J.Bruggeman,E.T.Buitenhuis,M.J.Church,A.M.Ciotti,S.C.Doney,M.Dowell,J.Dunne,S.Dutkiewicz,W.Gregg,N.Hoepffner,K.J.W.Hyde,J.Ishizaka*,T.Kameda,D.M.Karl,I.Lima,M.W.Lomas,J.Marra,G.A.McKinley,F.Mélin,J.K.Moore,A.Morel,J.O’Reilly,B.Salihoglu,M.Scardi,T.J.Smyth,S.Tang,J.Tjiputra,J.Uitz,M.Vichi,K.Waters,T.K.WestberryandA.Yool
Challengesofmodelingdepth-integratedmarineprimaryproductivityovermultipledecades:AcasestudyatBATSandHOT.GlobalBiogeochemicalCycles,24(3),GB3020,doi:10.1029/2009GB003655,2010.
17. Shibata,T.*,S.C.Tripathy*andJ.Ishizaka* Phytoplanktonpigmentchangeasaphotoadaptiveresponsetolightvariationcausedbytidal
cycle inAriakeBay,Japan.JournalofOceanography,66(6),831-843,doi:10.1007/s10872-010-0067-z,2010.
18. Short,D.A.andK.Nakamura* EffectofTRMMorbitboostonradarreflectivitydistributions.JournalofAtmosphericandOce-
anicTechnology,27(7),1247-1254,doi:10.1175/2010JTECHA1426.1,2010.19. Singh,P.*andK.Nakamura* Diurnalvariationinsummermonsoonprecipitationduringactiveandbreakperiodsovercentral
India and southern Himalayan foothills. Journal of Geophysical Research, 115, D12122,doi:10.1029/2009JD012794,2010.
20. Sojisuporn,P.,A.Morimoto*andT.Yanagi SeasonalvariationofseasurfacecurrentintheGulfofThailand.CoastalMarineScience,34(1),
91-102,2010.21. Son,Y.B.,T.Lee,D.-L.Choi,S.-T.Jang,C.-H.Kim,Y.H.Ahn,J.H.Ryu,M.Kim,S.-K.Jungand
J.Ishizaka* Spatialandtemporalvariationsofsatellite-derived10-yearsurfaceParticulateOrganicCarbon
(POC)intheEastChinaSea.KoreanJournalofRemoteSensing,26(4),421-437,2010.22. Takahashi,D.*,H.Miyake,T.Nakayama,N.Kobayashi,K.KidoandY.Nishida ResponseofasummertimeanticycloniceddytowindforcinginFunkaBay,Hokkaido,Japan.
ContinentalShelfResearch,30(13),1435-1449,doi:10.1016/j.csr.2010.05.003,2010.23. Takahashi,H.G.,H.Fujinami*,T.Yasunari*andJ.Matsumoto DiurnalrainfallpatternobservedbyTropicalRainfallMeasuringMissionPrecipitationRadar
(TRMM-PR)around the Indochinapeninsula.JournalofGeophysicalResearch,115,D07109,doi:10.1029/2009JD012155,2010.
24. Takahashi,H.G.,T.Yoshikane,M.Hara,K.TakataandT.Yasunari* High-resolutionmodellingofthepotentialimpactoflandsurfaceconditionsonregionalclimate
overIndochinaassociatedwiththediurnalprecipitationcycle.InternationalJournalofClimatol-ogy,30(13),2004-2020,doi:10.1002/joc.2119,2010.
25. Tripathy,S.C.*,J.Ishizaka*,T.Fujiki,T.Shibata*,K.Okamura,T.HosakaandT.Saino Assessmentofcarbon-andfluorescence-basedprimaryproductivityinAriakeBay,southwestern
Japan.Estuarine,CoastalandShelfScience,87(1),163-173,doi:10.1016/j.ecss.2010.01.006,2010.26. You,C.-H.,D.-I.Lee,S.-M.Jang,M.Jang,H.Uyeda*,T.Shinoda*andF.Kobayashi CharacteristicsofrainfallsystemsaccompaniedwithChangmafrontatChujadoinKorea.Asia-
PacificJournalofAtmosphericSciences,46(1),41-51,doi:10.1007/s13143-010-0005-1,2010.27. Zhao,X.,Y.Liu,H.Tanaka*andT.Hiyama Acomparisonoffluxvarianceandsurfacerenewalmethodswitheddycovariance.IEEEJournal
ofSelectedTopicsinAppliedEarthObservationsandRemoteSensing,3(3),345-350,doi:10.1109/JSTARS.2010.2060473,2010.
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2010
Annual Report
Hydrospheric Atmospheric Research Center (HyARC)
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