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IX General COSMO meeting Athens,18-21 September 2007

The COSMO-LEPS system: getting close to the 5-year milestone Andrea Montani, Chiara Marsigli and Tiziana Paccagnella ARPA-SIM Hydrometeorological service of Emilia-Romagna, Italy. IX General COSMO meeting Athens,18-21 September 2007. Motivations Methodology of COSMO-LEPS

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IX General COSMO meeting Athens,18-21 September 2007

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  1. The COSMO-LEPS system: getting close to the 5-year milestoneAndrea Montani, Chiara Marsigli and Tiziana PaccagnellaARPA-SIMHydrometeorological service of Emilia-Romagna, Italy IX General COSMO meeting Athens,18-21 September 2007 A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  2. Motivations • Methodology of COSMO-LEPS • Verification results: • SYNOP on the GTS • Future plans Outline A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  3. COSMO-LEPS (developed at ARPA-SIM) What is it? It is a Limited-area Ensemble Prediction System (LEPS), based on COSMO-model and implemented within COSMO (COnsortium for Small-scale MOdelling, which includes Germany, Greece, Italy, Poland, Romania, Switzerland). Why? Because the horizontal resolution of global-model ensemble systems is limited by computer time constraints and does not allow a detailed description of mesoscale and orographic-related processes. The forecast of heavy precipitation events can still be inaccurate (in terms of both locations and intensity) after the short range. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  4. 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, snowfall, …) generation of COSMO-LEPS in order to improve the Late-Short (48hr)to Early-Medium (132hr) range forecast of the so-called “severe weather events”. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  5. Dim 2 Possible evolution scenarios Cluster members chosen as representative members (RMs) Initial conditions Dim 1 LAM scenario Dim 2 LAM scenario LAM integrations driven by RMs LAM scenario Dim 1 Initial conditions COSMO-LEPS methodology ensemble size reduction A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  6. The COSMO-LEPS suite @ ECMWFNovember 2002 – May 2004 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 5 Representative Members Driving the 5 COSMO-model integrations oldest EPS oldest EPS Cluster Analysis and RM identification Cluster Analysis and RM identification 12 middle EPS 00 2 time steps youngest EPS 12 European area clustering period Complete Linkage COSMO-LEPS Integration Domain COSMO-LEPS clustering area A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  7. The COSMO-LEPS suite @ ECMWFJune 2004 – January 2006 3 levels 500 700 850 hPa 4 variables Z U V Q 10 Representative Members driving the 10 COSMO-model integrations employing either Tiedtke or Kain-Fristch scheme randomly choosen 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 in real time at ECMWF managed by ARPA-SIM; • Δx ~ 10 km • Fc length: 120h COSMO-LEPS Integration Domain COSMO-LEPS clustering area A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  8. The new COSMO-LEPS suite @ ECMWFsince February 2006 16 Representative Members driving the 16 COSMO-model 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 older EPS 00 2 time steps younger EPS 12 European area clustering period Complete Linkage • suite running as a ”time-critical application” managed by ARPA-SIM; • Δx ~ 10 km; 40 ML; • COSM0-LM 3.20 since Nov06; • fc length: 132h; • Computer time (4.3 million BU for 2007) provided by the COSMO partners which are ECMWF member states. COSMO-LEPS Integration Domain COSMO-LEPS clustering area A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  9. Present methodology A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  10. 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 “hindcast” run (ICs and 3-hourly BCs from ECMWF analyses) to “downscale” ECMWF information (start at 00UTC; t = 36h). Core products: 16 perturbed LM runs (ICs and 3-hourly BCs from 16 EPS members) to generate probabilistic output (start at 12UTC; t = 132h); A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  11. Dissemination • probabilistic products • deterministic products (individual COSMO-LEPS runs) • derived probability products (EM, ES) • meteograms over station points products delivered at about 1UTC to the COSMO weather services, to Hungary (case studies) and to the MAP D-PHASE and COPS communities (field campaign). A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  12. Objective verification of COSMO-LEPS • SYNOP on the GTS (COSMO-LEPS only); Verification package includes the traditional probabilistic scores: • Brier Skill Score (Wilks, 1995) • ROC area (Mason and Graham, 1999) • Cost-loss Curve (Richardson, 2000) • Percentage of Outliers (Buizza, 1997) • Ranked Probability Skill Scores (Wilks, 1995) A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  13. Objective verification of COSMO-LEPS • SYNOP on the GTS (COSMO-LEPS only); Main features: variable: 12h cumulated precip (18-06, 06-18 UTC); period: from Dec 2002 to Aug 2007; region: 43-50N, 2-18E (MAP D-PHASE area); method: nearest grid point; no-weighted fcst; obs: synop reports (about 470 stations x day); fcst ranges: 6-18h, 18-30h, …, 102-114h, 114-126h; thresholds: 1, 5, 10, 15,25, 50mm/12h; system: COSMO-LEPS both (57) monthly and (19) seasonal scores are computed. work is in progress for verification over the full domain (1500 stations) A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  14. Jun04: 5m  10m Feb06: 10m16m; 32ML  40 ML Time series of Brier Skill Score • BSS is written as 1-BS/BSref. Sample climate is the reference system. Useful forecast systems if BSS > 0. • BS measures the mean squared difference between forecast and observation in probability space. • Equivalent to MSE for deterministic forecast. BSS fc step: 30-42h • improvement of performance detectable for all thresholds along the years; • still problems with high thresholds, but good trend in 2007. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  15. fc step: 78-90h fc step: 30-42h Feb06: 10m  16m; 32ML  40 ML Jun04: 5m  10m Jun04: 5m  10m Feb06: 10m  16m; 32ML  40 ML Time series of ROC area • Area under the curve in the HIT rate vs FAR diagram. • Valuable forecast systems have ROC area values > 0.6. ROC • the positive impact of increasing the ensemble size in 2004 is evident for all thresholds and for different fcst ranges. • poor performance of the system in Spring and Summer 2006 (both particularly dry), despite upgrades. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  16. Feb06: 10m  16m; 32ML  40 ML Jun04: 5m  10m Outliers: time series + seasonal scores • How many times the analysis is out of the forecast interval spanned by the ensemble members. • … the lower the better … • Performance of the system assessed as time series and for 5 different Summers (JJA). OUTL • Evident seasonal cycle (more outliers in winter), but overall reduction of outliers in the years. • Reduction of outliers from one Summer to the other, related to the increase of ensemble size (more evident for the 5 to 10 increase). • Need to take into account the different statistics for each season (JJA 2003 less rainy than the others). A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  17. Semi-diurnal cycle in COSMO-LEPS scores • BSS score … the higher the better … • Performance of the system assessed for 5 different Summers (JJA). BSS • Evident 12-hour cycle in BSS scores (the same holds for RPSS, while less evident for ROC area scores). • Better performance of the system for “night-time” precipitation, that is for rainfall predicted between 18Z and 6Z (ranges 30-42h, 54-66h, …). • The amplitude of the cycle is somewhat reduced throughout the years and with increasing forecast range. • The bad performance in Summer 2006 is confirmed. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  18. Score dependence on the domain size (1) • Verification of COSMO-LEPS against synop reports over the MAP D-PHASE area (~ 470 stations; MAPDOM) and the full domain (~ 1500 stations; fulldom):  different statistics of the verification samples;  up to now, performance of the system over the 2 domains assessed only for the last 6 months (March-August 2007).  difficult to draw general conclusions A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  19. OUTL RPSS ROC Score dependence on the domain size (2) • RPSS score… the higher the better… (and positive). • ROC area… the higher the better… (and above 0.6). • Outliers percentage … the lower the better. • Smoother transitions from month to month in “fulldom” scores. • Slightly better performance of COSMO-LEPS over the MAPDOM, but the signal varies from month to month. • Higher predictability with orographic forcing?  Need to check individual regions and/or to stratify for type of stations. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  20. Main results • COSMO-LEPS system runs on a daily basis since November 2002 (6 “failures” in almost 5 years of activity) and it has become a “member-state time-critical application” at ECMWF ( ECMWF operators involved in the suite monitoring). • COSMO-LEPS products used in EC Projects (e.g. PREVIEW) , field campaigns (e.g. COPS, MAP D-PHASE) and met-ops rooms across COSMO community. Time series scores cannot easily disentangle improvements related to COSMO-LEPS itself from those due to better boundaries by ECMWF EPS. • Nevertheless, positive trends can be identified: • increase in ROC area scores and reduction in outliers percentages; • positive impact of increasing the population from 5 to 10 members (June 2004); • although some deficiency in the skill of the system were identified after the system upgrades occurred on February 2006 (from 10 to 16 members; from 32 to 40 model levels + EPS upgrade!!!), scores are encouraging throughout 2007. 2 more features: • marked semi-diurnal cycle in COSMO-LEPS scores (better skill for “night-time” forecasts); • better scores over the Alpine area rather than over the full domain (to be confirmed). A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  21. Future plans • Verification vs synop: assess performance over the full domain and consider other scores (Rank histograms, Reliability diagrams,…). • Implement “weighted” derived probability products: • weighted ensemble mean; • weighted ensemble standard deviation. • Introduce more model perturbations (see COSMO-SREPS approach). • Verification will be further developed → new variables verified. Implement EFI index in the operational suite? Implement “TIGGE-LAM compliant” COSMO-LEPS which can run on any domain, on any boundary conditions (relocatable COSMO-LEPS). Develop “hybrid” clustering (considering both ECMWF EPS and UKMO MOGREPS) ---> work with GRIB2 format! A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  22. Thank you ! A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  23. COSMO-LEPS 16-MEMBER EPS 51-MEMBER EPS MAM06 Average values (boxes 0.5 x 0.5) tp > 1mm/24h tp > 5mm/24h • As regards AVERAGE precipitation above these two threshols, the 3 systems have similar performance. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  24. ENSEMBLE SIZE REDUCTIONIMPACT EVALUATED ON CASE STUDIES (1) A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  25. 2003082512 Friuli(+72-+96) 5 RMs 10 RMs All 51 A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007 20 mm 100 mm

  26. 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: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  27. 2002111212 Piedmont 5 RMs 10 RMs All 51 A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007 20 mm 150 mm

  28. COSMO-LEPSReal time products A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  29. Operational COSMO-LEPS ~ Operational EPS “Friuli case” S.E. 153 5 RMs The youngest EPS A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  30. Operational COSMO-LEPS ~ Operational EPS : Friuli case probability maps – fc. range +96 >20mm/24h >50mm/24h COSMOLEPS EPS 51 members A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  31. EVALUATION OF S.E. SIZE (either 51, or 102, or 153) & ENSEMBLE SIZE REDUCTION (either 5 or 10 RMs) BSS outliers • Regarding the impact of the ensemble size, the difference between each 5-member ensemble and the correspondent 10-member ensemble is remarkable.The impact of doubling the ensemble size is almost the same for every configuration and is larger than impact of changing the number of EPSs on which the Cluster Analysis is performed (2 or 3). • Regarding the 5-RM ensemblesresults would seem to suggest that the use of just two EPS in the super-ensemble can be a good compromise, permitting to decrease the percentage of outliers significantly with respect of using just 1 EPS but leading only to a small decrease of the skill. old suite new suite A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  32. TEST OF NEW CLUSTERING VARIABLES AND/OR DIFFERENT 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 depends on the verification range. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  33. COSMO-LEPS derived probability products The generation of the Ensemble Mean (EM)and Ensemble Standard deviation (ES)was implemented and tested for COSMO-LEPS runs in terms of: Z700 - T850 – MSLP - T2M - UV10M - TP from fc+0h to fc+132h every 3 hours Dissemination will start at the end of the month. EM and ES are calculated without considering the weights relative to each integration. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  34. Why Limited Area Ensemble Prediction? • Global Ensemble Prediction Systems • have become extremely important tools to tackle the problem of predictions beyond day 2 • are usually run at a coarser resolution with respect to deterministic global predictions → skill inforecasting intense and localised events is currently still limited. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  35. Why Limited Area Ensemble Prediction? (2) As regards high resolution deterministic forecast in the short range, where limited-area models play the major role, a “satisfactory” QPF is still one of the major challenges. The same can be said for other local parameters. This is due, among other reasons, to the inherently low degree of predictability typical of severe and localised events. Probabilistic/Ensemble approach is so required also for the short range at higher resolution A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  36. From Global EPS to LAM EPS • In the Limited-area ensemble systems, tailored for the short range, perturbations must be already “active” during the first hours of integration • The characteristic of the LAM ensemble are strongly dependent by the lateral boundaries forcing. • Due to the “regional” application of these Limited Area Ensembles, methodologies can be different in different geographycal regions. A pratical consideration: Global EPS ~ Big Centres Limited Area EPS ~ (also) Relatively Small Centres A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  37. OBJECTIVE VERIFICATION OF COSMO-LEPS In the last period the verification package is being developed keeping into account two measure of precipitation: • the cumulative volume of water deployed over a specific region • the rainfall peaks which occur within this region COSMO observations A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  38. Verification grid OBS MASK CLEPS EPS A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  39. Archiving of C0SMO-LEPS • Deterministic run (fc+0h to fc+132h every 3h). • Ensemble Prediction System: • 16 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, …). • Derived products (fc+0h to fc+132h every 3h): ens-mean and ens-spread: Z700, T850, MSLP, T2M, UV10M, TP. From July 2005, products are archived on MARS at ECMWF A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  40. COSMO-LEPS 16-MEMBER EPS 51-MEMBER EPS 3 sis Average values boxes 0.5x0.5 deg tp > 1mm/24h tp > 5mm/24h A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  41. COSMO-LEPS 16-MEMBER EPS ave 0.5 NOCC=2671 tp > 1mm/24h NOCC=1195 tp > 5mm/24h NOCC=610 tp > 10mm/24h A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  42. COSMO-LEPS 16-MEMBER EPS 51-MEMBER EPS 3 sis Maximum values boxes 0.5x0.5 deg tp > 1mm/24h tp > 5mm/24h tp > 10mm/24h A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  43. COSMO-LEPS 16-MEMBER EPS Average values boxes 0.5x0.5 deg NOCC=227 tp > 20mm/24h A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  44. COSMO-LEPS 5-MEMBER EPS 51-MEMBER EPS Precipitation: average on 1.5 x 1.5 boxes ROC area tp > 10mm/24h tp > 20mm/24h • As regards AVERAGE precipitation above these two threshols, EPS wins. • Worsening due to the ensemble reduction • Positive impact of LM downscaling SON 2003 A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  45. COSMO-LEPS 5-MEMBER EPS 51-MEMBER EPS maximaon 1.5 x 1.5 boxes ROC area tp > 20mm/24h • COSMO-LEPS is more skilful than EPS in forecasting correctly high precipitation values over a rather large area. Number of occurrences: 600 (20 mm threshold) and 150 (50 mm). tp > 50mm/24h SON 2003 A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  46. fc step: 78-90h Jun04: 5m  10m Feb06: 10m  16m; 32ML  40 ML Time series of ROC area for COSMO-LEPS (2) • Area under the curve in the FAR vs HIT diagram. • Valuable forecast systems have ROC area values > 0.6 ROC • the positive impact of increasing the ensemble size in 2004 is evident for all thresholds and for different fcst ranges. • poor performance of the system in Spring and Summer 2006, despite system upgrades. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  47. COSMO-LEPS 16-MEMBER EPS 51-MEMBER EPS MAM06 Average values (boxes 0.5 x 0.5 deg) A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  48. Time series of TEST OF NEW CLUSTERING VARIABLES AND/OR DIFFERENT 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 depends on the verification range. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  49. Main results • COSMO-LEPS system runs on a daily basis since November 2002 and it has become a “member-state time-critical application” at ECMWF ( partial involvement of ECMWF operators in the suite management). • Time series scores identify positive trends in the performance of the system: • increase in ROC area scores and reduction in outliers percentages; • positive impact of increasing the population from 5 to 10 members (June 2004); • some deficiency in the skill of the system identified after the system upgrades occurred on February 2006 (from 10 to 16 members; from 32 to 40 model levels + EPS upgrade!!!)  need of further investigation. • High-resolution verification shows better scores of COSMO-LEPS with respect to EPS in forecasting precipitation maxima within boxes. No clear impact of the weighting procedure as regards precipitation, BUTCOSMO-LEPS ensemble mean for 2m temperature has better skill (lower standard deviation to observations) with weighting the ensemble members according to cluster populations compared to the mean with unweighted members. A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

  50. LAM Nesting Ensemble Size Reduction COSMO LEPS Approach Global Ensemble LAM members GCM members Representative members Downscaling LAM Nesting Total Downscaling (Brute-Force Approach) Global Ensemble GCM members LAM members A.Montani; The COSMO-LEPS system: 5-year milestone COSMO meeting, Athens, 18-21 September 2007

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