1. RSMC La Réunion activities regarding SWFDP Southern Africa Matthieu Plu (Météo-France, La Réunion), Philippe Arbogast (Météo-France, Toulouse), Nicole Girardot (Météo-France, Toulouse)

2. RSMC La Réunion Since 1993, Météo-France La Réunion: WMO « Regional Specialized Meteorological Centre » (RSMC) for tropical cyclones in the South-West Indian Ocean (SWIO)

3. RSMC La Réunion Cyclone activity in the SWIO : –12% of the total worldwide cyclone activity (more than the North Atlantic) –Impacts : many human losses every year (particularly in Madagascar), and significant economical impact in the richer countries (example : Dina 2002 95 M losses in La Réunion) Role of RSMC La Réunion for tropical cyclones : –Provide appropriate guidance information (analyses, forecasts) in real- time to the member countries of AR I –Climatology, database of TC –Training and R&D activities

4. OUTLINE : Contributions of RSMC La Réunion in SWFDP Southern Africa 1.Aladin-Reunion 2.Website of RSMC La Réunion 3.R&D activities

5. 1. Aladin-Réunion Since 2006, Météo-France (RSMC La Réunion) has been operating the ALADIN-REUNION model Main features : 8km horizontal resolution 3D-Var assimilation 70 vertical levels 3-days leadtime forecasts twice a day (at 00UTC and 12UTC)

6. 1. Aladin-Réunion ALADIN-REUNION = an adaptation of ALADIN for the tropical regions 3D-wind bogus to improve tropical cyclones forecasts The 3DVar errors are computed over the domain Some specific physical parameters (convection, ocean fluxes) Performance Good skill for cyclone forecasts (tracks and intensity) Very informative for wind and precipitation forecasts over La Réunion Island Well appreciated by the meteorological services involved in SWFDP (according to the last SWFDP Technical meeting, Mauritius, July 2011) SWFDP dissemination –Sent to Pretoria and displayed on RSMC Pretoria website –Displayed on RSMC La Réunion website

7. 2. Website of RSMC La Réunion Purpose : –Provide guidance in real-time regarding tropical cyclones, and extreme wind and rainfall –A limited-access to the SWFDP and RA I national meteorological services –Available in two languages: French & English Input data : –Aladin-Reunion forecast fields –For each cyclone, the official RSMC track forecast –Deterministic models (Météo-France, ECMWF, UKMO) –Forecast tracks from ensembles (PEArp, ECMWF EPS, NCEP, CMC, MOGREPS) –Fields (mslp, wind, rainfall) from ensembles (PEArp, ECMWF EPS, NCEP, CMC)

8. 2. Website of RSMC La Réunion Permanent products: –Aladin-Réunion forecasts (00UTC and 12UTC, until 84h) –Probabilities and quantiles of strong winds and intense rainfall for 4 ensembles + multi-ensemble –mslp spaghettis forecasts (for cyclogenesis) for 4 ensembles + multi- ensemble In case of a cyclone in the basin: –Official RSMC track forecast + uncertainty cone –Track forecasts from deterministic models –Tracks, live time, Strike probabilities, track for the 5 ensembles + multi- ensemble

9. 2. Website of RSMC La Réunion

10. 90 kt 85 kt80 kt Illustration : Bingiza (Feb. 2011)

11. 2. Website of RSMC La Réunion Early detection of the cyclogenesis of Bingiza

12. Illustrations sur le cas de Bingiza (février 2011) Early detection of the cyclogenesis of Bingiza

13. Illustrations sur le cas de Bingiza (février 2011) Early detection of the cyclogenesis of Bingiza

14. Illustrations sur le cas de Bingiza (février 2011) Early detection of the cyclogenesis of Bingiza

15. Illustrations sur le cas de Bingiza (février 2011) Early detection of the cyclogenesis of Bingiza

16. Illustrations sur le cas de Bingiza (février 2011) Early detection of the cyclogenesis of Bingiza

17. Illustrations sur le cas de Bingiza (février 2011) Early detection of the cyclogenesis of Bingiza

18. Illustrations sur le cas de Bingiza (février 2011) Early detection of the cyclogenesis of Bingiza

19. 2. Website of RSMC La Réunion Official RSMC forecast Uncertainty cone (derived from EPS) Track forecasts from deterministic models

20. 2. Website of RSMC La Réunion Strike probabilities (PEArp)

21. 2. Website of RSMC La Réunion Probability of high rainfall (PEArp)

22. 2. Website of RSMC La Réunion Probability of high rainfall (EPS)

23. Probability of high rainfall (NCEP)

24. 2. Website of RSMC La Réunion Aladin-Réunion forecast : mslp, rain and wind

25. 2. Website of RSMC La Réunion Official RSMC forecast Uncertainty cone (derived from EPS) Track forecasts from deterministic models

26. 2. Website of RSMC La Réunion

31. 3. R&D activities The evolutions of Aladin-Reunion (assimilation, physics) : a collaboration between RSMC La Réunion and CNRM (Météo- France, Toulouse)

32. 3. R&D activities Uncertainty cones –Based on ECMWF EPS: a case-dependent cone reference : Dupont et al, 2011, Weather & Forecasting, Verification of ensemble-based uncertainty circles around tropical cyclone track forecasts, in press. –At a given lead-time, the circle that centered on the ensemble- mean and that contains 75% of the EPS members is computed –This circle is translated to the RSMC position forecast The ensemble dispersion of TC positions is translated to the RSMC forecast such a cone is proven to be able to discriminate between large and small errors !

33. 3. R&D activities Future R&D activities: –Comparison of the ensemble track forecasts from different ensembles, and from multi-ensemble –Calibration of the ensemble forecasts for wind and precipitation –A major difficulty: verification and calibration of ensemble forecasts where the observations are sparse reference : Dupont et al, 2011, Weather & Forecasting, Verification of ensemble-based uncertainty circles around tropical cyclone track forecasts, in press.