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Monthly Forecasting

Monthly Forecasting. Frederic Vitart ECMWF, Reading, UK. Monthly Forecasting System. Real-time forecast: Coupled ocean-atmosphere integrations: a 51-member ensemble is integrated for 32 days every Thursday.

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Monthly Forecasting

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  1. Monthly Forecasting Frederic Vitart ECMWF, Reading, UK

  2. Monthly Forecasting System • Real-time forecast: • Coupled ocean-atmosphere integrations: a 51-member ensemble is integrated for 32 days every Thursday. • Atmospheric component: IFS with the latest operational cycle and with a TL159L40 resolution • Oceanic component: HOPE (from Max-Planck Institute) with a zonal resolution of 1.4 degrees and 29 vertical levels • Coupling: OASIS (CERFACS). Coupling every ocean time step (1 hour) • Background statistics: • 5-member ensemble integrated at the same day and same month as the real-time time forecast over the past 12 years

  3. Model Changes during the past year • New versions of IFS : • Cycle 28R2 in June 2004 • Cycle 28R3 in October 2004 (contains a new physic package) • Cycle 29R1 in April 2005 (contains a new moist boundary layer scheme) • Operational suite (October 2004): • The frequency of the monthly forecast is once a week instead of once every two weeks. • Starting date is Thursday instead of Wednesday • Product dissemination on Fridays • Hindcast and real-time forecast are archived under different streams (mnfc and mnfh) • Model climatology and anomalies relative to the model climate are archived

  4. Performance over the Northern Extratropics ROC area of probability of 2-meter temperature in upper tercile Persistence of previous week probabilities Monthly Forecast Day 12-18 Day 19-32 DJF03 DJF04 DJF05 DJF04 DJF03 DJF05

  5. Verification: Week 10/01/2005-16/01/2005

  6. Verification: Week 24/01/2005-30/01/2005

  7. Verification: Week 21/02/2005-27/02/2005

  8. Verification: Week 07/03/2005-13/03/2005

  9. Verification: Week 21/03/2005-27/03/2005

  10. Monthly Forecast 13/01/2005 Day 12-18 Day 5-11

  11. Future developments (1) • End of June : • Cycle 29R2 • New sea-ice treatment: • Current scheme: • The sea-ice cover is a diagnostic of the ocean model. • There is sea ice if SST is lower than a certain threshold (about -1.7C) • New scheme (Magdalena Balmaseda and Tim Stockdale) • During the first 10 days, sea-ice is persisted from the atmospheric initial conditions. • After 1 month, we impose climatological sea-ice (from ERA40) • Between day 10 and month 1, interpolation between persisted sea-ice and climatological sea-ice.

  12. Example: Sea-ice cover on 1/1/2005 NEW Scheme: Current Scheme:

  13. Future developments (2) • Archiving of probabilities: • 1) Probability of weekly mean precipitation and temperature anomalies to be • above or below a threshold • 2) Terciles, quintiles, 10% and 90% distributions of weekly mean precipitation • and temperature relative to the model climatology. The boundaries will • also be archived.

  14. Future developments (3) • Verification plots on the web site (under development): • - Verification of anomaly maps of 2-meter temperature, Z500, precipitation…. • - Some probabilistic scores • - Some deterministic scores • The verification plots will be updated every week

  15. Examples of verification Anomaly maps: Z500 Temperature

  16. Examples of verification Examples of probabilistic scores: ROC scores

  17. Examples of verification Example of deterministic scores:

  18. Future developments (4)SYSTEM changes • Autumn 2005: CY30R1. The resolution of the monthly forecasting system will • change from TL159L40 to TL159L62. The additional vertical levels will be in the • mid-troposphere. • 2006: Merging the monthly forecasting system with VAREPS.

  19. Future developments (5)Merging the monthly forecasting system with VAREPS Present situation: 2 separate systems EPS: TL255L40 twice a day uncoupled Day 10 Day 0 TL159L40 once a week MOFC: Day 0 Day 32 Ocean model

  20. Future developments (6)Merging the monthly forecasting system with VAREPS End of 2005: 2 separate systems VAREPS: TL399L62 TL255L62 twice a day uncoupled Day 15 Day 0 Day 7 TL159L62 once a week MOFC: Day 0 Day 32 Ocean model

  21. Future developments (7)Merging the monthly forecasting system with VAREPS 2006: single system VAREPS: twice a day Once a week TL399L62 TL255L62 Day 15 Day 0 Day 7 TL255L62 (*) MOFC: Ocean model (once a week) Day 0 Day 32 * To be confirmed

  22. Future developments (8)SYSTEM changes • 2006 : Merging the monthly forecasting system with VAREPS. • New MARS archiving for this system. For example stream mnfc will become enfo • Hindcasts will still be produced with the same resolution as the full VAREPS • system. This could also be useful for calibrating medium-range weather forecasts.

  23. Madden Julian Oscillation Experiments: 15/12/92-31/01/93 ERA40 Analysis: Velocity Potential 200 hPa U850 OLR

  24. MJO ExperimentsVelocity Potential correlation Persistence of atmos. initial conditions Persisted SSTs Coupled Observed SSTs

  25. MJO ExperimentsVelocity Potential correlation Mixed-layer model 10-meter vertical resolution Mixed-layer model Coupled

  26. Real-time monthly forecasts (81 cases) Loss of Variance PC1 Fcst PC2 Fcst PC1 Analysis PC2 Analysis

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