The COSMO-LEPS Suite at ECMWF: Present Status and Developments

1. The COSMO-LEPS suite at ECMWF: present status and developmentsAndrea MontaniARPA-SIM Hydrometeorological service, Bologna, Italy COSMO meeting, Zurich, 20-23 September 2005 A.Montani; The COSMO-LEPS suite at ECMWF: present status and developments COSMO meeting, Zurich, 20-23 September 2005

2. Outline Introduction Present status: archiving of COSMO-LEPS products; test of different configurations of the clustering-selection technique. Related projects: SPITLAEF (case studies + tests); SPCOLEPS (Alpine suite); SPCOWIND (related to wind forecast); DEISA (related to hydrological forecasting). Future plans: COSMO-LEPS as a “time-critical application” at ECMWF; “respond” to ECMWF EPS upgrade? A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

3. Introduction What is it?It is a Limited-area Ensemble Prediction System (LEPS), based on Lokal Modell and developed within COSMO (COnsortium for Small-scale MOdelling, which includes Germany, Greece, Italy, Poland and Switzerland). Why?The horizontal resolution of global-model ensemble forecast systems is limited by computer time constraints and does not allow a detailed description of mesoscale and orographic-related processes. COSMO-LEPS project: combine the advantages of global-model ensembles with the high-resolution details gained by the LAMs, so as to identify the possible occurrence of intense and localised weather events (heavy rainfall, strong winds, temperature anomalies, …); COSMO-LEPS forecasts to improve the short to medium-range forecast (48h < t < 120h) of the so-called “severe weather events”. A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

4. The COSMO-LEPS suite @ ECMWFsince June 2004 10 Representative Members driving the 10 Lokal Modell integrations (weighted according to the cluster populations) employing either Tiedtke or Kain-Fristch convection scheme (randomly choosen) 3 levels 500 700 850 hPa 4 variables Z U V Q d+3 d+4 d d+5 d+1 d+2 d-1 Cluster Analysis and RM identification Cluster Analysis and RM identification middle EPS 00 2 time steps youngest EPS 12 European area clustering period Complete Linkage • suite running every day at ECMWF managed by ARPA-SIM; • Δx ~ 10 km; 32 ML; • LM_3.15 since 18/4/2005; • fc length: 132h; • Computer time provided by the COSMO partners which are ECMWF member states. COSMO-LEPS Integration Domain COSMO-LEPS clustering area A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

5. Operational set-up Additional products: • 1 deterministic run (ICs and 3-hourly BCs from the high-resolution deterministic ECMWF forecast) to assess the relative merits between deterministic and probabilistic approach (start at 12UTC; t = 132h); • 1 proxy run (ICs and 3-hourly BCs from ECMWF analyses) to “downscale” ECMWF information (start at 00UTC; t = 36h). Core products: 10 perturbed LM runs (ICs and 6-hourly BCs from 10 EPS members) to generate probabilistic output (start at 12UTC; t = 132h); A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

6. Dissemination to the COSMO community (+ Hungary) A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

7. Archiving of C0SMO-LEPS products • Deterministic run (fc+0h to fc+132h every 3h). • Ensemble Prediction System: • 10 perturbed forecasts (fc+0h to fc+132h every 3h): PLEV (500, 700, 850 hPa): Z, RH, T. SURF: albedo, LCC, MCC, TCC, SW radiation flux, CAPE, hzerocl, snowlmt, mslp, T_2m, Td_2m, TMAX_2m, TMIN_2m, U_10m, V_10m, UVMAX_10m, large-scale rain, convective rain, large-scale snow, TP. • Forecast probability (various intervals and thresholds): SURF: CAPE, hzerocl, TMAX_2m, TMIN_2m, UVMAX_10m, TP, snowfall, showalter index. • Clustering information (population, clustering variable used, …). From 1 July 2005, COSMO-LEPS forecasts are archived on MARS at ECMWF (class=co). back archiving of past runs (from 5/11/2002 onwards) will start soon. A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

8. Clustering-selection technique EVALUATION OF THE METHODOLOGY with respect to clustering settings: • clustering intervals (SON 2003) • ensemble size (JJASON 2004) • clustering area (JJASON 2004) Verification against “proxy-rain” (ECMWF deterministic forecast starting at 00 UTC and cumulated from fc+6h to fc+30h). A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

9. CLUSTERING INTERVALS • Consider a fixed configuration in terms of ensemble size (10 RMs selected out of 2 EPS sets, 2eps-10rm) and the properties of the “reduced” (10-member) global ensemble in 4 different cases: OPE: the 10 members are selected like in the operational set-up (clustering variables: z,u,v,q; clustering levels: 500, 700, 850 hPa; clustering times: fc+96h, fc+120h); D2: like OPE, but clustering times: fc+24h, fc+48h; D3: like OPE, but clustering times: fc+48h, fc+72h; D4: like OPE, but clustering times: fc+72h, fc+96h. outliers BSS Brier Skill Score: OPE has slightly better scores at all verification ranges (less evident for ROC area .. not shown); Outliers percentage: results heavily depend on the verification range. A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

10. ENSEMBLE SIZE and CLUSTERING AREA (1) • Evaluation of the properties of the reduced global ensemble for 3 different ensemble sizes (either 10, or 15, or 20 RMs selected out of 2 EPS sets, 2eps-10rm, 2eps-15rm, 2eps-20rm) and 2 different clustering areas. 2eps-10rm (ope): the 10 members are selected like in the operational set-up (clustering variables: z,u,v,q; clustering levels: 500, 700, 850 hPa; clustering times: fc+96h, fc+120h); 10 alp: like OPE, but the clustering area is centred over the Alps (43-49N, 4-16E); 2eps-15rm: like OPE, but 15 members are selected; 2eps-20rm: like OPE, but 20 members are selected. Outliers (fulldom) BSS (fulldom) Brier Skill Score: 2eps-20rm has better scores at all verification ranges; larger impact from 10 to 15 members rather than from 15 to 20 members (the same for ROC area .. not shown); Outliers percentage: the same story. A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

11. ENSEMBLE SIZE and CLUSTERING AREA (2) • Evaluation of the sensitivity to the clustering area used to select the RMs: 2eps-10rm (ope): 10 members selected with the operational clustering area (30-60N, 10W-30E); 10 alp: like OPE, but the clustering area is centred over the Alps (43-49N, 4-16E); 2eps-15rm: like OPE, but 15 members are selected; 2eps-20rm: like OPE, but 20 members are selected. Outliers (alpdom) ROC (alpdom) BSS (alpdom) ROC area: due to the smaller verification area, there are very few occurrences at high thresholds; this gives lesser statistical significance to the scores, despite the long verification period. No positive impact of reducing the clustering area (actually “ope” is slightly better than “10 alp”!); small impact in terms of BSS (at fc+66h). Outliers percentage: the same story as for the ROC area. A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

12. Related projects SPITLAEF (Italian ECMWF special project) to perform studies on limited-area ensemble size, clustering methodologies, model perturbations, EPS reruns, … • SPCOLEPS (joint Italy and Switzerland ECMWF special project) to study possible modifications of the operational suite. • SPCOWIND (joint Italy and Great Britain): new ECMWF special project so as to have the computer resources to run a limited-area ensemble system over North-Western Europe (within the EC project PREVIEW, WP: Windstorms). DEISA (Distributed European Infrastructure for Supercomputer Applications): consortium of super-computing centres which can (hopefully!) provide computer time resources to rerun 1 full month (August 2002) of COSMO-LEPS forecasts for ensemble hydrological purposes (within the EC project PREVIEW, WP: Medium-range Plain-floods). A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

13. ALPINE suite (running on SPCOLEPS billing units) • Experimental suite running daily from 15 July 2005. • Same configuration as the operational COSMO-LEPS (red), but both clustering and integration domain are centred over the Alps (blue). • Products not yet disseminated, but saved at ECMWF. ope alp • On single events, differences between the 2 suites can be noticeble: Prob maps of 3-day rainfall exceeding 50 and 100 mm (fc24-96h); forecast starting at 20050905 12UTC  In this case, more helpful maps from the Alpine suite A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

14. NW Europe suite (running on SPCOWIND billing units) • Generation of a new limited-area ensemble forecast system for the prediction of wind and wind gusts over North-Western Europe. • Aim: provision of site-specific wind forecasts to be post-processed and combined with other products by UK Met. Office. • Same configuration as the operational COSMO-LEPS (red), but both clustering and integration domain are shifted northwards (blue). Experimental suite will start on June 2006. A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

15. Future plans • COSMO-LEPS suite will soon become a “time-critical” application monitored by ECMWF: • involvement of ECMWF operators in the management of the suite; • file system dedicated and priority in job scheduling. • Implement dissemination to the Czech Met. Service (if possible). • Back archiving on MARS of past runs (from 5/11/2002 onwards). • Modify (?) the operational configuration to “contrast” EPS upgrade: • EPS will increase the hor. res. from 80 to 50 km (TL255L40  TL399L62) with 56-57 model levels between 40 hPa (approximate top-level height of LM) and the surface; • EPS will have HIGHER vertical resolution than LM; is this a problem??? • increase the COSMO-LEPS vertical resolution from 32 to 40 layers so as to reduce the gap? • ask for 3-hour post processing of EPS until fc+144h. • Study the outcome of the Alpine and of the NW-Europe suites. A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

16. Thank you ! A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

17. ENSEMBLE SIZE REDUCTIONIMPACT EVALUATED ON CASE STUDIES (2) Observed precipitation between 15-11-2002 12UTC and 16-11-2002 12 UTC Piedmont case A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

18. 20 mm 150 mm 2002111212 Piedmont(fc+72-96) 5 RMs 10 RMs All 51 A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

19. COSMO-LEPS clustering-selection technique EVALUATION OF THE METHODOLOGY with respect to clustering settings: • ensemble size • clustering times • clustering area • ADDED VALUE WITH RESPECT TO EPS OBJECTIVE VERIFICATION OF COSMO-LEPS • ADDED VALUE WITH RESPECT TO EPS • evaluated at different spatial scales • evaluated over different geographical regions • evaluated for two different convection schemes 2 related ECMWF Special Projects ongoing: • SPITLAEF in cooperation with UGM • SPCOLEPS in cooperation with Meteo-Swiss A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

20. 51 51 51 Ensemble Size Reduction Different Ensemble reductions Lokal Modell Nesting 20 20 Ensemble Size Reduction Lokal Modell Nesting 10 10 Ensemble Size Reduction Lokal Modell Nesting 5 5 ENSEMBLE SIZE REDUCTION: Friuli case study set-up Lokal Modell Nesting 1 EPS Total Downscaling (BFA) 51 51 A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

21. RMs vs ECMWF Proxy rain EVALUATION OF SUPER-ENSEMBLE (S.E.) SIZE & ENSEMBLE SIZE REDUCTION 1 EPS 51 members Ensemble Size Reduction 2 EPS 102 members Lokal Modell Nesting 10 10 RMs Ensemble Size Reduction 3 EPS 153 members Lokal Modell Nesting 5 5 RMs A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

22. ENSEMBLE SIZE REDUCTIONIMPACT EVALUATED ON CASE STUDIES (1) A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

23. TP24h > 20 mm TP24h > 100 mm 2003082512 Friuli (fc+72-96h) 5 RMs 10 RMs All 51 A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005

24. COSMO-LEPS as a “time-critical” application COSMO-LEPS EVALUATION OF THE METHODOLOGY with respect to: • ENSEMBLE SIZE REDUCTION • SUPER-ENSEMBLE SIZE • CLUSTERING SETTING (parameters, time range, areas) • impact of weighting • ADDED VALUE WITH RESPECT TO EPS related ECMWF Special Projects ongoing: • SPITLAEF in cooperation with UGM (for research) • SPCOLEPS in cooperation with Meteo-Swiss (Alpine suite) • SPCOWIND (?) in cooperation with UK Met Office (Northern Europe suite) A.Montani; The COSMO-LEPS system: recent developments and plans 2nd Workshop on Short-Range EPS, Bologna, 7-8 April 2005