Products of the JMA Ensemble Prediction System (EPS) for Seasonal Forecast Shuhei Maeda Climate Prediction Division [email protected] Contents 1. Introduction 2. Products of the EPS for one-month prediction 3. Products of the EPS for three-month outlook 4. Remarks TCC Web page http://cpd2.kishou.go.jp/tcc/ One-month prediction Three-month outlook 2. Products of the EPS for onemonth prediction 1) Outline of the EPS 2) Performance of the system 3) Examples of products The EPS for one-month prediction Analysis Atmosphere Atmospheric Model Land Boundary Condition (AtmosphereLand) Ocean SST persisted SST anomaly Products • Map • Verification ・GPV Horizontal resolution Time integration range Executing frequency Ensemble size SST Physical processes T106 (about 1.125 º Gaussian grid ~110km) 34 days Once a week 26 members persisted anomaly The same as those of shortand medium- range forecast model Example of ensemble prediction Initial Spread W Ensemble mean Each member 7 day running mean Z500 normalized anomaly over the western North Pacific (40N,140E-170E) Products Kind Forecast range Ensemble 2-8day mean 9-15day map 16-29day 2-29day Parameter (NH) Z500,Z500A T850,T850A PSEA PSEAA ＊○○○A: (60N-60S and Asia) Z500,Z500A SLP,SLPA PSI200,PSI200A PSI850,PSI850A CHI200,CHI200A T2m,T2mA RAIN,RAINA,SSTA anomalies of ○○○ (continue) Products Forecast range Parameter Spread map 2-8 day Z500A 9-15 day Large 16-29 day anomaly index* map 2-29 day Time series 7-day running (each mean member) Circulation indices (Z500A) Area averaged T850A Area averaged spread (Z500A) CHI200 in the equatorial region *Ratio of number of members whose anomaly is higher than 0.5SD to total number of ensemble menber at each grid point 2) Performance of the system Example of one-month prediction verification charts W Anomaly correlation scores of ensemble mean forecast in 2001 28 day (2-29) mean 500hPa height fields over the Northern Hemisphere. Initial: 2001/1/4-2001/12/27 W RMSE of ensemble mean forecast in 2002 28 day (2-29) mean 500hPa height fields over the Northern Hemisphere. Initial: 2002/1/3-2002/12/27 Example of verification of probabilistic one-month prediction Event (E) Z500 anomaly is greater than 0 Frequency of occurrences where E was forecast within each of the probability category bins W Forecast frequency distribution Reliability diagram for 7 day mean 500hPa field: day 9-15 2003 Spring (2003/2/27-5/29) 3) Examples of products Prediction of ・Arctic Oscillation ・Rossby waves along Asia jet ・Intra Seasonal Oscillation in the tropics (Madden Julian Oscillation (MJO)) Example of one-month prediction products(1) Ｚ５００ Ｚ５００ analysis forecast AO ! T850 T850 analysis forecast W Ensemble average forecast map ( Initial: 2002/10/24) Northern Hemisphere Z500 and T850 ; 28day mean Many members predict large Z500 anomaly (above 0.5*standard deviation) Many members predict large Z500 anomaly (below 0.5*standard deviation) W Large anomaly index map Init:2002.10.24 28 day mean ( day:2-29) W Analysis and ensemble average Each member Analysis 7 day running mean Z500 normalized anomaly over North western Pacific (40N,140E-170E) Example of one-month prediction Oct Nov products(2) Dec Jan Time sequences of temperature anomalies in Japan (5 day running mean) 2001.10-2002.1 Normalized temperature anomalies 2002.1.11-15 W What? Prediction of the Rossby wave along Asia jet PSI200 analysis 1/12-1/18 PSI200 forecast W Ensemble average forecast map ( Initial: 2002/1/3) PSI200 ; 7day mean (9-15 day forecast range) Rossby wave guide along Asia jet Dispersion relation of barotropic Rossby wave in U(y) is ω＝Uk-β＊k/K2, here, β＊ ＝ β-∂2U/ ∂y2 , K2 ＝k2+l2. Therefore, total wave number of a stationary Rossby wave is K＝Ks＝（ β＊/U)1/2. Hoskins and Ambrizzi(JAS,1993,1661-) showed that if Ks has maximum at some latitude as figure 1, it works as “Rossby wave guide” latitude Schematic figure of Rossby wave guide Climatological Ks in DJF (shade) and Analyzed stream function anomaly at 200hPa (2002.1.11-15) Temperature anomalies, and Rossby wave along Asia jet W W Normalized temperature anomalies Stream function (200hPa) anomalies Longitude and height cross section of 20N-30N averaged stream function anomaly 2002.1.11-15 Time-longitude cross-section of stream function anomaly (20N-30N) at 200 hPa initial 2002.1.3 (left) analysis (right) ensemble mean forecast Spread among ensemble members W Spread among ensemble members ( Initial: 2003/10/16) Z500 ; 7day mean (9-15 day ) Predicted stream function (200hPa) anomalies and wave activity flux of two of 26 ensemble member Example of one-month prediction products(3) 96015 98618 Observed amount of daily precipitation in MAY 2003 What ? ? 97430 91425 1 10 20 30 MAY 2003 Eastward propagation of MJO 1-5 May 2003 6-10 May 11-15 May 16-20 May Velocity potential (200hPa) OLR 1 May day Velocity potential (200hPa) in the equatorial region W longitude 20 May Schematics of MJO 3-D structure over the Indian Ocean Rui and Wang(1990) Prediction of MJO in May 2003 Observation 2nd week prediction ( 7 day mean) Velocity potential anomalies (200hPa) Stream function anomalies W (200hPa) 2003/5/3-5/9 Ensemble mean Initial:2003/4/24 Observation 2nd week prediction Velocity potential anomalies (200hPa) Stream function anomalies W (200hPa) 2003/5/10-5/16 Ensemble mean Initial:2003/5/1 Observation 2nd week prediction Velocity potential anomalies (200hPa) 2003/5/17-5/23 W Ensemble mean Initial:2003/5/8 Stream function anomalies (200hPa) Prediction of MJO in Oct. 2003 Init:10/9 2nd week 20 Sep day Obs. 10 Oct CHI200a Fcst W Longitude PSI850a Velocity potential at 200hPa (CHI200) PSI200a Prediction of MJO in July 1984-1993 OBS FCST 1 84 31 86 92 88 CHI200A in the equatorial region
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