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Seasonal forecasts Laura Ferranti and the Seasonal Forecast Section

Seasonal forecasts Laura Ferranti and the Seasonal Forecast Section. User meeting 15-17 June 2005. Outline:. Performance 2004-2005 Drought conditions over the Iberian peninsula Progress with the multi-model system Some results from the experimentation done to test the next system (S3).

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Seasonal forecasts Laura Ferranti and the Seasonal Forecast Section

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  1. Seasonal forecastsLaura Ferrantiand the Seasonal Forecast Section User meeting 15-17 June 2005

  2. Outline: • Performance 2004-2005 • Drought conditions over the Iberian peninsula • Progress with the multi-model system • Some results from the experimentation done to test the next system (S3).

  3. 2004-2005 Performance • Monsoon 2004 • Tropical storm activity • Anomalously cold Feb 2005

  4. JJA 2004 SST anomaly Op. anal-era40 (1987-2001) SST predictions for the JJA 2004i.c. 01/05/2004

  5. Prob. for the below normal category Ensemble mean anomaly GPCP anomalies (1987-2001) PrecipitationJJA 2004

  6. Observed tropical storm frequency over the Atlantic: Over Western North Pacific: Tropical storm activity: 2004 Climate

  7. 2mt anomalies JFM 2005

  8. January February March 2005

  9. Seasonal forecast performance JFM 2005 Z 500 Feb 2005

  10. Accumulated precip 1 Sept 2004 – 10 June 2005

  11. Accumulated precip 1 Oct 2004 – 31 May 2005 % of normal Instituto da Água, Portugal

  12. Precipitation, Centre/South Portugal Instituto da Água, Portugal Accumulated Accumulated, climate Monthly precipitation

  13. 2005 2003 2004 2002 2001 Southern Iberian Peninsula 40-37N 9E-0W: Precipitation (GPCP) Soil Moisture months months

  14. Seasonal predictions of precipitations:

  15. 2005 2003 2004 2002 2001 summer 2005 versus summer 2003 Soil Moisture Precipitation (GPCP) 40-50N 0-15E

  16. JJA 2005 Probability of 2m Temp > upper tercile of the model climate JJA 2003

  17. ECMWF Probability of 2m Temp > upper tercile of the model climate for JJA 2005 Météo France Met Office Forecasts start 1 May 2005

  18. Conclusions • Predictions of the monsoon precipitation for JJA 2004 verified well. • Over the West Pacific basin the forecast predicted successfully higher tropical storm activity than the climatology. Over the Atlantic the forecast has not been as good. • Beyond the first month the skill of the seasonal forecast for a single month can be limited by the chaotic nature of the atmosphere. • Dry conditions over the Iberian Peninsula were consistently predicted since November 2004. • For the next summer warm anomalies are predicted over the South-western Europe.

  19. Multi-model : • Verification of the individual multi-model component is completed this includes the original and revised Météo France system. • Multi-model products as well as their verification is in progress. • What issues are involved for reaching the operational status: • - A suitable hind-cast ensemble size covering the same period. • - Some coordination on how to display the products on the web.

  20. Météo France S1 Météo France S2

  21. Météo France S1 Météo France S2

  22. System 3 experimentation:

  23. System 3 experimentation: Too weak easterlies

  24. System 3 experimentation:

  25. Experimentation for System 3: • Results from coupled integrations with a more recent version of the atmospheric model (CY29R1) indicate generally a higher skill except for a specific season and location. • This seems to be related with the mean state of the atmospheric model that tends to underestimate the easterlies over the central tropical Pacific. • One possible solution to this problem may be a correction term during the model integration. • Further experimentation is in progress including the testing of the latest atmospheric cycle.

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