COSMO meeting, Zurich, 20-23 September 2005

1. COSMO-LEPS: operational aspects and verificationAndrea Montani, Chiara MarsigliARPA-SIM Hydrometeorological service, Bologna, Italy COSMO meeting, Zurich, 20-23 September 2005 A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

2. Outline Introduction Present status: archiving of COSMO-LEPS products; test of different clustering-selection techniques. Related projects: SPITLAEF (case studies + tests); SPCOLEPS (Alpine suite); SPCOWIND (related to wind forecast); DEISA (related to hydrological forecasting). Verification results. Future plans: COSMO-LEPS as an ECMWF “time-critical application”; “respond” to ECMWF EPS upgrade? A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

6. Dissemination to the COSMO community (+ Hungary) A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

8. 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

9. 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

10. COSMO–LEPS verification (SON 2004) Verification grid A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

11. Grid point forecast Verification of the distributions The verification has been made in terms of: • Average value • Maximum value • 50th percentile (Median) • 90th percentile in a box Station observation A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

12. tp > 10mm/24h tp > 10mm/24h tp > 20mm/24h tp > 20mm/24h tp > 30mm/24h COSMO-LEPS 10-MEMBER EPS Average values boxes 1.5x1.5 deg A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

13. COSMO-LEPS 10-MEMBER EPS Average values boxes 1.5x1.5 deg A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

14. tp > 10mm/24h tp > 10mm/24h tp > 20mm/24h tp > 20mm/24h COSMO-LEPS 10-MEMBER EPS Maximum values boxes 1.5x1.5 deg tp > 30mm/24h A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

15. COSMO-LEPS 10-MEMBER EPS Maximum values boxes 1.5x1.5 deg A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

16. 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 CAREFULLY the outcome of the Alpine suite. A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

17. Thank you ! A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

18. tp > 10mm/24h tp > 10mm/24h tp > 20mm/24h tp > 20mm/24h tp > 30mm/24h COSMO-LEPS 10-MEMBER EPS 50th percentile values boxes 1.5x1.5 deg A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

19. COSMO-LEPS 10-MEMBER EPS 50th percentile values boxes 1.5x1.5 deg A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

20. tp > 10mm/24h tp > 20mm/24h tp > 30mm/24h COSMO-LEPS 10-MEMBER EPS 90th percentile values boxes 1.5x1.5 deg tp > 10mm/24h tp > 20mm/24h A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

21. COSMO-LEPS 10-MEMBER EPS 90th percentile values boxes 1.5x1.5 deg A.Montani; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

22. 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

23. 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

24. 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

25. 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005

26. 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; COSMO-LEPS: operational aspects and verification COSMO meeting, Zurich, 20-23 September 2005