3. Products of the EPS for three-month outlook 1) Outline of the EPS 2) Examples of products 3) Performance of the system The EPS for three-month outlook Analysis Atmosphere Atmospheric model Land Boundary Condition (AtmosphereLand) Ocean SST persisted SST anomaly Horizontal resolution Time integration range Executing frequency Ensemble size Products • Guidance • Map • …... T63 (about 1.875 º Gaussian grid ~180km) 4 months Once a month 31 members What can a model predict ? Where does the signal of long-range forecast come from ? Response of atmosphere to the slowly varying boundary conditions Especially, SST anomalies in the tropics such as ENSO → Anomalies of large scale convective activity → Anomalies of large scale divergence flow → Anomalies of tropical circulation direct and indirect influence on the circulation in the mid- and high- latitudes Linear response on heating in the tropics : Matsuno-Gill response Symmetric heating on the equator Heating u,v,w Rossby wave u, v, p in the low level L L Kelvin Wave * tropical circulation is depicted approximately. Gill.A.E.(1980) QJRMS,447 - Circulation anomalies associated with ENSO (DJF) Stream function at 200hPa Stream function at 850hPa W OLR Composite Map in El-Nino years Example of three-month outlook products(1) OBS DJF 2002/03 Init:2002/11/10 FCST and Error Precipitation anomalies Stream function anomalies at 200hPa W Error of Stream function anomalies at 200hPa Example of three-month outlook products(2) 1999.12 ( Very Cold in the Indochina Peninsula) W Example of three-month outlook products(2) 1999.12 ( Very Cold in the Indochina Peninsula) Init:1999/11/30 OBS FCST Precipitation anomalies Stream function anomalies at 850hPa Example of three-month outlook products(3) DJF 2003/04 Init:2003/11/15 SSTA Stream function at 200hPa Precipitation Velocity potential at 200hPa W at 850hPa Configuration of Seasonal forecast experiment (Hindcast) Model : JMA AGCM(T63v0103) Target years : 1984 to 2001, 18 years Target months : All months ( initial date is the end of every month) Integration time : Four months Atmospheric initial condition : ERA-15 from 1984 to 1993, and JMA’s operational global analyses from 1994 to 2001 Land surface initial condition : Land surface initial condition: Output from SiB forced by ERA-15 from 1984 to 1993, and 10year average of them for 1994 to 2001 SST : Anomaly at initial date is persisted during the forecast period Ensemble size : Five members Verification of circulation fields (Z500) 13-months running mean :above 0.5 :above 0.4 El Nino La Nina W Anomaly correlation scores (ACC) of 90 day mean 500hPa geopotential height at 21-110 forecast range for all cases (1984.1-2001.12). North Pacific(20N-90N,90E-90W) region Verification of circulation fields (Z500) All cases ENSO years .5 (top left): Nrothern Hemisphere (20N-90N) 0 (top right): Eurasia (20N-90N,0-180E) (bottom left):North Pacific .5 (20N-90N,90E-90W) (bottom right) East Asia 0 (20N-60N,90E-170E) Month to month variation of anomaly correlation scores (ACC) of 90 day mean 500hPa geopotential height at 21-110 forecast. Verification of temperature at 2m and precipitation Standard Verification System (SVS) for Long-range Forecast T2m JAS (init:5/31) Precipitation MSSS Corre lation W Could the model predict summer season climate in Asia and Pacific region? Prediction of precipitation in summer (JJA) Distribution of interannual temporal correlation coefficients between observed (CMAP) and model ensemble average forecast precipitation for 18 years (1984-2001). Initial: 30 April Forecast range: 31-120day (90 day mean) Prediction of precipitation in the western North Pacific summer monsoon (WNPM) region (110-160E,10-20N) Day: 31-120 Initial:4.30 Observation Ensemble average Marks Each forecast Interannual variations of observed and model precipitation anomaly in the western North Pacific summer monsoon region (110-160E,1020N) in JJA (Relationship between activities of WNPM and lower tropospheric circulation) Distribution of interannual temporal correlation coefficients between area averaged precipitation(110E-160E,10N20N) and stream function at 850hP in JJA for 18 years (1984-2001). Prediction of westward extension of North Pacific subtropical High in summer Observation Ensemble average Marks Each forecast Lu and Dong(JMSJ,2001) Interannual variations of observed and model 850hPa vorticity anomaly in NPSH region (110-140E,10-30N) Initial: 30 April forecast range:31-120 day Prediction of summer (JJA) in 1998 Precipitation PSI850 observation observation forecast forecast Initial: 31 May 1998 Forecast range: 1-90 day Remarks 1) Prediction skills should be checked before you use the products. 2) Improvement of the EPS for seasonal forecast is required.
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