Verification activity in sub seasonal forecasting at jma
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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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Verification activity in sub seasonal forecasting at jma

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


Verification of sub seasonal forecast

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


Verification of hindcast

Verification of Hindcast


Setups of hindcast

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


Verification scores

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


Provision of skill assessment

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


Actions needed for hindcast verification

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


Verification of real time forecasts

Verification of Real-time Forecasts


Score dependence on periods of climatology

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


Score dependence on periods of climatology1

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


Interannual variability of scores

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


Interannual variability of scores1

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


Planned and ongoing activity in verification

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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