1. Impact of using merged regional operational L3 in the operational Meteo-France regional Aladin model to forecast Mediterranean convective events Françoise Orain (Meteo-France CMS),Françoise Taillefer (Meteo- France CNRM),Pierre Le Borgne (MF CMS), Hervé Roquet ( MF CMS )

2. 2 OUTLINE  Introduction  L3 Description  CANARI analysis Description  Aladin model Description  Ingestion of L3 SST into Canari  Case Study : A September 2007 strong convective event  Conclusion and further works

3. 3 INTRODUCTION State of the art at Meteo France and objectives...  Micro wave SST have already been found to impact positively on prediction of cyclone intensity in La Reunion ( Arnaud Coupin, Ghislain Faure, Samuel Westrelin, see Orain et al GHRRT-09, Perros-Guirec )  In this case, using satellite SST impacts more than improving flux parameterization  Preliminary studies by Cindy Lebeaupin (2007) have shown the utility of better accounting for SST in simulation of convective systems in Mediterranean sea  Mersea L3 SST offered the possibility of extensive use of SST fields in this context.

4. 4

5. 5  Satellite SST have been used only as relaxation in models.  Surface data are of lower priority in 3DVAR model assimilation scheme  There is a misunderstanding of the satellite SST by modellers  But… following Mersea, L3 are being ingested in test mode in the Canari (analysis) scheme for Météo-France  In the present phase, we are trying to demonstrate the usefulness of ingesting satellite SST at small scale. BACKGROUND Up to now

6. 6  Implementation of an ingestion step :  L3P merged + CANARI Analysis + ALADIN forecast

7. L3 production : methodology of the mersea chain at CMS AATSR AVHRR NAR17 NAR18 GOES- 12 1h MSG1 1h AMSREBUOYS AVHRR GAC NAR17 NAR18 AVHRR LAC NAR17 NAR18 TMI AVHR R GOES- 12 1h MSG1 1h AMSR E BUOY S AVHR R GAC NAR17 NAR18 AVHR R LAC TMI AATSR REFERENCE Interpolation 5° BIASES L2P COLLECTION STEP CORRECTION OF L2P WITH REFERENCE AATSR CMS NON CORRECTED COLLATED L3 1 by day / sensor Minus 194 files, 19 Go Choice of a geographical zone Z Choice of a Resolution R 1 bias/day/sensor conservation 10 days bias MERGED CORRECTED SUPERCOLLATED L3 ANALYSIS L4 Choice of a geographical zone Z’<Z Choice of a Resolution R’<=R CORRECTED COLLATED L3 L2P Disponibility J-1 Supercollated Atlantic zone at J 6H local Analysis Duration is function of the zone and resolution Correction Correction phase in parallel

8. 8 L3P mergedL4 (analyse) L3P Goes L3P Nar17 L3P seviri_1h L3P avhrr17_L L3P amsre L3P Nar18 L3P avhrr17_G L3P avhrr18_G L3P tmi L3P avhrr18_L Products of the Mersea chain at CMS 5 km daily

9. 9 L3 merged

10. 10 L3P Surface CANARI analysis Uninitialized Analysis

11. 11  available, robust, modular ( adapted resolution according to the scale of models or phenomena studied 10 km, 5 km, 2 km )  most of adjusting parameters of optimal interpolation can be reached easily by namelist (weight of observation, errors…)  compatible and remained into Aladin3Dvar and after into Arome  Allow useful regional coefficients For this experiment on the western Mediterranean sea :  Standard deviation of observation error of L3 satellite SST: 1.5°C  Standard deviation of error of the guess: 0.8 °C  Resolution 10 km, horizontal length scale 200 km  Very few L3 SST observations have been rejected (62894 observations ). Advantages of the CANARI Analysis Bad condition for SST !

12. 12  Limited area model  Based on Arpege software (Meteo France or ECMWF-IFS )  Non hydrostatic  Resolution: 9.8 km  Coupled with Arpege model ALADIN model

13. 13 What is a Cevenol event ???  Conflict between warm sea and cold air from atmosphere  Meteorological situation said in « omega » or blocked  Most countries around Mediterranean sea are concerned.  Energy exchanges tends to balance the vertical gradients between the atmospheric boundary Layer and Oceanic Mixed Layer  Creating (in autumn) heavy stationary convective precipitations violent Thunderstorms, flash floods due to the topography of this region near mediterannean sea and mountain (Cevennes)

14. 14 Meteorological situation 28th -29th of september 2007 and precipitations

15. 15 EXPERIMENT ON A CEVENOL EVENT FROM THE MEDUP data base Case of 28th-29th-30rd septembre 2007 Night observations 201 mm Sommières 220 mm Verargues

16. 16 L3P merged CMS (supercollated 5 km) from 29/09/2007 L4 (Analyse Mersea CMS 5km) 29/09/2007 ZOOM L3Pmerged Mediterran é e ZOOM L4 Mersea CMS M é diterran é e 5km Zoom on the Western Mediterranean SST COOLING SST Cooling

17. 17 28th of september 2007 29th of september 2007 30th of septembre 2007 Contribution of satellite SST Cooling off the Provence coast In Celsius Back to normal

18. OSTIA Met office Globale 6km MERSEA CMS Atlantique 5 km( L3Pmerged no buoys ) CANARI without L3Pmerged CANARI with L3Pmerged Comparison between Mersea Analysis (Ostia and CMS) and operational analysis Canari without L3 and with L3P merged (no buoys )

19. OSTIA (Met Office) 6km CANARI without L3P merged only buoys CANARI with L3P merged, no buoys 28 th of September 2007 OH TU 29 th of September 2007 OH TU 30 th of September 2007 OH TU Comparison of OSTIA and CANARI ANALYSIS

20. MERSEA CMS 5 km no buoy CANARI without L3P merged CANARI with L3P merged (no buoy) 28th of september 2007 OH TU 29th of september 2007 OH TU 30th of septembre 2007 à OH TU Comparison Mersea CMS analysis and CANARI

21. 21 Differences between the 2 analysis CANARI « with L3Pmerged » and without L3Pmerged On 28th,29th et 30th of septembre 2007 Sommi è res Evident impact of the benefit of L3Pmerged  Warmer area of 3 degrees Celsius near the coast.  But also colder area about 1°8 C.  The area disappears day after day because the atmosphere capted the energy as in cyclone and because of mixing of water with wind. 28th september 2007 00HTU 29 th september 2007 00HTU 30 th september 2007 00HTU

22. Impact of the Canari analysis from the 29 th of september on 24 H forecast for the 30th of september 2007 à 00H Aladin r é solution 9,8 km Difference of Heat sensitive flux in W/m ² Difference of mean Heat latent flux in W/m ²

23. 23 Forecast of Cape ( Convective avalaible potential energy ) in Joule/Kg for the 30 th of september 2007 à 00H without L3P and with avec L3P We can notice : increase of about 100 joules for Cape in the forecast with L3 merged on the cevenol zone on the sea the form of the cape is very different so the bring of SST L3P merged modifies the forecast On the other hand : no improvement on the localization With L3Pmerged Without L3Pmerged

24. 24 With L3Pmerged Without L3Pmerged Cumulative precipitation of the 24 Hours forecast for the 30th of september 00H between the 29th of september and the 30th of septembre 2007 without L3Pmerged and with L3Pmerged We expected better, but the model has no time to be stabilized with a one day SST

25. 25 With L3Pmerged Without L3Pmerged Dynamical experiment with 3Dvar assimilation and use of 3 consecutive CANARI surface analysis from 27th to 29th of September to reinitialize the system Sans L3With L3

26. 26 CONCLUSIONS  A feasibility study on a CEVENOL case with SST from Mersea has been led at CMS using the operational METEO-FRANCE tools  The sensitivity of the analysis and of the forecast model to L3P SST has been demonstrated.  When doing impact studies, care must be taken to run the experiment over several days (and not one single day)

27. 27  MERSEA is over but the 2 km resolution MyOcean L3P are operational from April 2009 and will be included into the Meteo France operational data bases  More cases will be studied to benefit from the amelioration of fluxes parameterization in the ALADIN model.  A PhD thesis will be conducted to improve interface ocean-atmosphere description over the Mediterranean  Test of several fields per day (including DW) with a research model (Arome) in preparation of the HYMEX campaign in 2011. PERSPECTIVES L3Pmerged(haut), L4 Myocean 2km, Europe 3 octobre 2008L3Pmerged (haut), L4 R é union 2km

28. 28 MERCI