jma monthly and seasonal forecast systems 1 yuhei takaya [email protected] climate prediction...

JMA Monthly and JMA Monthly and Seasonal Forecast SystemsSeasonal Forecast Systems

1

Yuhei [email protected]

Climate Prediction DivisionJapan Meteorological Agency

Workshop on “Sub-seasonal to Seasonal Prediction”, Exeter, UK, 1-3 Dec. 2010

• Designing Operational Forecast Systems• Targets (Phenomena, Time scales, Applications)• Requirements/Limitations

• Current JMA Operational Systems• Monthly (uncoupled) and Seasonal (coupled)

forecast systems• Practical Examples

• Future Directions• Required Activities

Outline


• Operational Forecast Systems are to be oriented to phenomena, user applications.

10 102 103 104

Time scale (hours)

Hor

izon

tal s

cale

(km

)

2

20

200

2,000

20,000

1d 10d 1m 3m

“Designing” Operational Forecast Systems


ENSOMonsoon

MJO

Synoptic

Weather

Systems Teleconnection

sTropical

Cyclone

Seasonal EPS (CGCM TL95 180 km)

Monthly EPS , Early Warning on ExtremeEvents (TL159 110 km)

Weekly /Typhoon EPS (TL319 60 km)Deterministic (JMA-GSM, TL959 20 km)

JMA-NHM (5 km)LFM (2 km)

Atmospheric

convection

Mesoscale

Weather

System


Current JMA Sub-seasonal to Seasonal Prediction Systems

1 month 　　　　　　 3 months 　　　　 7 months 　　

Early warning information onextreme events

1-month forecast

3-month forecast

Warm/cold

season forecast

ENSOoutlook

operatedmodelsAGCM

TL159L6050 member

CGCMJMA/MRI-CGCM

AGCM: TL95L40OGCM:

0.3 -1 deg x 1 deg

51 member

2 weeks

week 1

Week 2

Week 3&4

1 month3 months

3 months(summer/winter)

ENSO, Indian Ocean SST

The seasonal forecast system and ENSO prediction system were integrated with an atmosphere-ocean coupled model in Feb. 2010. The seasonal forecast system and ENSO prediction system were integrated with an atmosphere-ocean coupled model in Feb. 2010.

Issued on Tuesday/Friday

Issued on Friday

Issued every month

Issued in Feb. Sep.

Issued every month

• Computer Resources• Costs & Benefits

Requirements and Limitations


• Higher Resolution• Higher Frequency• More Members

T850Z500&WAF200Precipitation, PSI200, WAF200

X200 and Div WindSST

6

T850Z500&WAF200

X200 and Div WindSST

7

Precipitation, PSI200, WAF200

Precipitation, PSI200, WAF200

Predictability in the Midst of Chaos - Predictability at SSS Time Scale- (Shukla 1998 Science )


JMA Monthly Forecast System

Atmospheric General Circulation Model(JMA-GSM0803C)

TL159L60 (~110km)

JMA Global Data Assimilation System

Atmospheric perturbationsTrop.&Ext.-trop. bred vector

Atmospheric I. C.


JMA Land Surface Analysis

25 members start from Wednesday.25 members start from Thursday. 50 members in total

Arctic Oscillation during Dec. 2009-Feb. 2010

Dec. 2009

• A negative phase of the Arctic Oscillation (AO) pattern was dominant through Winter 2009/2010.

Jan. 2010 Feb. 2010

-300 -180 -60 0 60 180 300 [m]

10

Forecast Skill of Operational JMA Monthly Forecast


Week 1 Week 2 Week 3-4 Week 1-4

Ano

mal

y C

orre

latio

n

12

AO index in Winter 2009/2010

(1) 2009/12/10 　 (2) 2010/1/28

Spatial Pattern of GPH500 EOF1 (Area weighted Covariance, 22.6 %)Computed with 1979-2005 DJF mean 500-hPa GPH.

Index of EOF1 score (500hPa GPH, DJF mean)

The winter 2009/2010 was the most prominent period during 1979-2010.


• 1-month (4-week) mean Anomaly Correlation 0.84 Week 1 0.93, Week 2 0.77, Week 3-4 0.56

13

Prediction for negative AO Case Initial Date: 2009/12/10

Analysis (JRA-25) Forecast

1-month （ 4-week ） mean 500-hPa GPH Anomaly

1209060300 -30-60-90-120[m]

0.84


200-hPa Westerly Jet Initial Date: 2009/12/10

200-hPa Zonal Wind Anomaly 4-Week Mean Forecasts

Forecast I.C.; 2009/12/09 Forecast I.C.:2009/12/10Analysis (12/12-1/8)

[m/s] Strong Sub-tropical Jet Weak Polar Front Jet


14

14

• Momentum Transport Diagnostics: E-vector E=(v’2-u’2, -u’v’)

15

E-vector (Hoskins et al. 1983 JAS)

E

Anti-CyclonicCirculation

Cyclonic Circulation

Divergence Convergence

Ian N. James (1994) “Introduction to Circulating Atmospheres”

Anti-CyclonicCirculation

Cyclonic Circulation


16

Divergence of E-vectorMid-latitude 30N-40N

North Pacific 30N-40N, 170E-120W

North Atlantic 30N-40N, 90W-0

● 　 Hindcast (Initial Date: 10 Dec.)　　 Operational Forecast (2009/12/10)○ 　 JRA-25/JCDAS Analysis

x104 [m s-2]

x104 [m s-2]

x104 [m s-2]

• The seasonal forecast relies on the predictability that comes from the ENSO variability.

• The East Asian monsoon is essentially an ocean-atmosphere-land coupled system.

• Coupled models are suitable for predicting its variability at a seasonal time scale.

JMA Seasonal EPS


The new JMA coupled forecast system has been up and running for the JMA ENSO prediction system since Feb. 2008, and was introduced to the JMA seasonal forecast in Feb. 2010.

The new JMA coupled forecast system has been up and running for the JMA ENSO prediction system since Feb. 2008, and was introduced to the JMA seasonal forecast in Feb. 2010.

New JMA Seasonal Forecast System

coupler(w/ flux adjustment)

Climate Data AssimilationJRA-25/JCDAS

Atmosphere-Ocean Coupled model (JMA/MRI-CGCM)

JMA GSM（ TL95L40: ~180km ）

Ocean model (MRI.COM )

1.0°×(0.3°-1.0°), 51 levels

Ocean Data Assimilation System

MOVE/MRI.COM-G

Atmospheric perturbationsTrop.&Ext. trop bred vector

Atmospheric I. C.

Oceanic I. C.Atmospheric BGM + Lagged

Averaging Forecast


Operational Schedule


10 daysWindow

Ocean Data Assimilation

Forecasts9 members / 5 days

LAF

NINO3 SSTA

South China Flood in 2010

BBC News http://news.bbc.co.uk/2/hi/asia-pacific/4617891.stm


Precipitation Forecasts for June 2010 (I.C. : May)

Beijing ECMWF Exeter Melbourne

Montreal Moscow Seoul Tokyo

Toulouse Washington

WMO LC website http://www.wmolc.org/

Observation; OLR anomaly

(mm/day)

Original data are provided by NOAA.

22

• Weekly EPS • TL479L100 (~40 km) in 2013

• Monthly EPS• TL319L100 (~60 km) in 2013 • Development of integrated Weekly EPS and Monthly EPS

(Seamless system) is under discussion.

• Seasonal EPS• AGCM: TL159L60 (80?) (~110 km) in 2014• OGCM: Tripolar grid, 1deg x 0.3-0.5 deg. 53 levels.

JMA future plan on the next HPC


• The lead time is important at a 1-month time scale.

Forecast Skill wrt Lead Time


50 ensembles50 ensembles

Based on verification of real-time JMA operational forecasts in 2006.

ACC (Daily 500-hPa GPH) ACC (7-day mean 500-hPa GPH)

Scores if forecasts 3-day before used.

Toward “Seamless Prediction System”


Weekly EPS(TL479L100)

2-Week EPS (Early Warning)

Monthly EPS (TL319L100)reforecast

2-Week EPS (TL479L100)reforecast

Monthly EPS (TL319L100)reforecast

2-Week EPS (TL479L100)reforecast

Monthly EPS (TL319L100)

Week-1 Week-2 Week-3 Week-4

FY2013-

FY ?

FY ???

• International research projects to investigate predictability at monthly time scale 　 (extended TIGGE ???)

• International research projects for key processes of predictability, MJO, ENSO, etc… 　 (CLIVAR MJO WG etc. )

• Standard verification framework for operational forecasts at sub-seasonal (monthly) time scale. (under WMO, CBS? SVS?)

Required Activities for Further Improvement of SSS time scale



END

EOF1(AO), REOF(PNA, NAO) Scores Initial Date: 2009/12/10

(a) EOF1 22.6 %

(b) REOF1 16.6 % (c) REOF2 16.1 %

AO, NAO, PNA Indices were well predicted.

Red ： Ensemble meanBlue ： AnalysisGrey ： Each realization

Contours: 300-hPa Zonal Wind Anomaly [m s-1] Colors: High-Frequent Wave Activity Anomaly x 10-5 [m2 s-2]

30

High-Frequency Wave Activity Anomaly K=½(u’2+v’2) 　 Initial Date: 2009/12/10

K anomaly and U300 Anomalies Analysis (JRA-25 , 12/12-1/8)

K anomaly and U300 Anomalies Ensemble Forecast ( I.C. 12/10)


Contours; Convergence of Eddy Momentum Flux by High-Frequency Variation ∂y (-u’v’) (contour interval: 2 ・ 10-4 [m s-2] )

Colors: 300-hPa Zonal Wind Anomaly [m s-1]

31

Convergence of Momentum Flux ∂y (-u’v’) and U300 Initial Date: 2009/12/10∂y (-u’v’), U300 Anomaly Analysis (JRA-25 , 12/12-1/8)

∂y (-u’v’), U300 Anomaly Ensemble Forecast ( I.C. 12/10)


Ensemble Perturbations


The JMA monthly forecast system produces initial perturbations using the Bred Vectors, which is specially intended to obtain large-scale growing modes in the tropics.

Chikamoto et al. 2007, GRL

Tropical Bred Vector Perturbation


Hovmoeller diagrams of 200-hPa velocity potential averaged over the 10S–10N region for (a) the observed field, (b) the bred vector

The space-time spectrum of the 200-hPa velocity potential of the tropical bred vector averaged over the 10S–10N region.

• Old • Singular Vector with a simplified model (NH only)

• New• Combination of BV method in the tropics and

extra-tropics (NH only).

Perturbation (500-hPa GPH Spread)


OLD NEW NEW-OLD

Courtesy: M. Hirai@JMA

[m]

• Perturbations in tropics contribute to increase of the spread in extra-tropics.

Perturbation and Spread-Skill Relationship


N. H. S. H.

New RMSEOld Spread

Courtesy: M. Hirai@JMA

Precipitation in June 2010

Zhejiang 174 %

Fuzhou 157 %

Based on CLIMAT reports


Ratio to Normals

37

Index of 1st Mode


Wand and Fan Index : U850 (5-15N,90-130E) – U850 (22.5-32.5N,110-140E)

The 1st mode is well correlated with Wang and Fan Index (Wang and Fan ,1999).

Index of the 1st Mode

• Z500

2009/12/10


Forecast I.C.; 2009/12/10Analysis (12/12-1/8)

• T850

2009/12/10



• SLP

2009/12/10



jma monthly and seasonal forecast systems 1 yuhei takaya [email protected] climate prediction...

Documents