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Verification Activity in Sub-seasonal Forecasting at JMA

Verification Activity in Sub-seasonal Forecasting at JMA. Climate Prediction Division / JMA Yuhei Takaya WWRP/THORPEX/WCRP Sub-seasonal to Seasonal Implementation Planning Meeting 2-3 December 2011, Geneva Switzerland

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Verification Activity in Sub-seasonal Forecasting at JMA

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  1. Verification Activity in Sub-seasonal Forecasting at JMA Climate Prediction Division / JMAYuhei Takaya WWRP/THORPEX/WCRP Sub-seasonal to Seasonal Implementation Planning Meeting 2-3 December 2011, Geneva Switzerland Thanks to N. Adachi

  2. Verificationof Sub-seasonal Forecast • Verification of real-time operational forecastMonitoring of the performance of real-time operational forecasts on a routine basis. • Verification of hindcastAssessing the performance of forecast systems using hindcasts (re-forecasts) for every implementation of systems. Climate Prediction Division, JMA

  3. Verification of Hindcast

  4. Setups of Hindcast • 5 members from 3 initial dates in all months during last ~ 30 years (currently 1979-2009) The last day of the month 10th 20th Climate Prediction Division, JMA 5 members

  5. Verification Scores • Verification of JMA monthly EPS is based on the SVS-LRF. • Scores include deterministic scores (i.e., RMSE, ACC)as well as probabilistic scores (i.e., ROC, BSS). • Reference data are JRA-25 re-analysis, GPCPprecipitation. 0.8 0.6 0.5 ROC scores for 2-29 days mean precipitation (I.C.: Nov. 30 1979-2009) Climate Prediction Division, JMA

  6. Provision of Skill Assessment • Our sub-seasonal/seasonal forecasts are provided together with skill assessment based on hindcasts.Tokyo Climate Center: http://ds.data.jma.go.jp/tcc/tcc/products/model/ http://ds.data.jma.go.jp/tcc/tcc/products/model/map/1mE/map1/pztmap.php Climate Prediction Division, JMA

  7. Actions Needed for Hindcast Verification • The number of ensemble members (5 members) is not enough to get precise assessments of the performance. • Supplementary experiments with a larger number of ensemble members for limited initial dates. • This would be done in collaborative work of development of integrated EPS. • Current verification focus on forecast skill rather than representation of processes. • More process-oriented verification would be needed. • Representation from a viewpoint of climate modeling.(e.g., energy budget at the surface and TOA, MJO, etc… ) Climate Prediction Division, JMA

  8. Verification of Real-time Forecasts

  9. Score Dependence on Periods of Climatology Anomaly correlation of GPH500 for 1979-2004, 1981-2010 climatology (operational forecasts during 2009/03/26-2011/04/21) 28 days mean 1981-2010 climatology Week-1 Week-2 Week-3&4 1979-1994 climatology Climate Prediction Division, JMA

  10. Score Dependence on Periods of Climatology Anomaly correlation of GPH500 for 1979-2004, 1981-2010 climatology (operational forecasts dufing 2009/03/26-2011/04/21) 28 days mean 1981-2010 climatology Week-1 Lesson : ACC scores are affected by change of climatology periods. Week-2 Week-3&4 1979-1994 climatology

  11. Interannual Variability of Scores TL159L40 / 50-member improved radiation scheme COBE-SST (for B.C.) T106L40 (Top 0.4hPa) BGM(NH)/26-member BGM(NH+TRO) land analysis Sc scheme SSM/I improved BGM(TRO) improved Cu conv. Scheme improved radiation Scheme TL159L60 (Top 0.1hPa) improved Cu conv. scheme improved gr. wave scheme improved Cu conv. scheme Climate Prediction Division, JMA

  12. Interannual Variability of Scores TL159L40 / 50-member improved radiation scheme COBE-SST (for B.C.) T106L40 (Top 0.4hPa) BGM(NH)/26-member • Lessons from this exercise: • Forecast skill would be affected by the inherent predictability of the climate variability. • Sufficient length (samples) of forecast data is needed to verify the performance of sub-seasonal forecast systems. • It is better to use both hindcasts and operational forecasts to assess the performance of forecast systems. BGM(NH+TRO) land analysis Sc scheme SSM/I improved BGM(TRO) improved Cu conv. Scheme improved radiation Scheme TL159L60 (Top 0.1hPa) improved Cu conv. scheme improved gr. wave scheme improved Cu conv. scheme Climate Prediction Division, JMA

  13. Planned and Ongoing Activity in Verification • Ongoing work • Integrated verification environment for an experiment system of integrated EPS (weekly-monthly) . • Re-assessment of operational forecast scores with the consistent JRA-25 analysis. (Previously forecast skill has been routinely verified against the deterministic analysis at the time.) • Future work… • More appropriate setups in order to verify EPS performance. (5 members hindcasts are obviously NOT enough!) • Verification of precipitation with in-situ observations. Climate Prediction Division, JMA

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