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XI General COSMO meeting Offenbach,7-10 September 2009

Clustering of multi-model global ensembles for dynamical downscaling purposes: first steps Andrea Corigliano, Andrea Montani ARPA-SIMC Hydrometeorological Service of Emilia-Romagna, Bologna, Italy. XI General COSMO meeting Offenbach,7-10 September 2009. Description of the work Present status

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XI General COSMO meeting Offenbach,7-10 September 2009

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  1. Clustering of multi-model global ensembles for dynamical downscaling purposes: first stepsAndrea Corigliano, Andrea MontaniARPA-SIMCHydrometeorological Service of Emilia-Romagna, Bologna, Italy XI General COSMO meeting Offenbach,7-10 September 2009 A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  2. Description of the work • Present status • Future plans Outline A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  3. 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: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  4. COSMO-LEPS suite @ ECMWF: present status 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) + perturbations in turbulence scheme 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 runs as a “time-critical application” managed by ARPA-SIMC; • Δx ~ 10 km; 40 ML; fc+132h; • COSM0 v4.7 since Feb09 (with Runge-Kutta + multi-layer soil scheme); • computer time (6.0 million BU for 2009) provided by the COSMO partners which are ECMWF member states. COSMO-LEPS Integration Domain COSMO-LEPS clustering area A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  5. Multi-model clustering: first approach 1 level 500 hPa 1 variable Z d+3 d+4 d d+5 d+1 d+2 d-1 16 Representative Members are selected Cluster Analysis and RM identification Cluster Analysis and RM identification UKMO MOGREPS 1 time step ECMWF EPS 12 European area clustering time Complete Linkage COSMO-LEPS Integration Domain COSMO-LEPS clustering area A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  6. Methodology Cluster members chosen as representative members (RMs) initial conditions by EPS Possible evolution scenarios initial conditions by MOGREPS • Consider both ECMWF EPS and UKMO MOGREPS and study properties of cluster analysis on multi-ensemble: • How many times do the 2 ensembles mix? • Where do the RMs come from? How to they score depending on their “origin”? • BEFORE DOWNSCSALING: is there added value with respect to single-model ensemble? • AFTER DOWNSCALING: is there added value with respect to single-model ensemble? A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  7. data from TIGGE-PORTAL (everything in GRIB2); • consider 180 forecast cases: 90 days (MAM09) of ECMWF-EPS and UKMO-MOGREPS run at 00 and 12 UTC; • use Z500 at fc+96h as clustering variable; • for verifying analysis (at 00 and 12 UTC), consider Z500: • “consensus analysis” (average of UKMO and ECMWF high-res analyses), • independent analysis (e.g. from NCEP); • generate the following global ensembles: • EPS (50+1): 51 members • MOGREPS (23+1): 24 members • MINI-MIX (EPS24 + MOGREPS24): 48 members • MEGA-MIX (EPS51 +MOGREPS24): 75 members Forecast and analysis datasets A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  8. perform cluster analysis with 16 clusters and select RMs (like in operations); • generate 16-member global ensembles (EPS_REDU, MOGREPS_REDU, MINI_REDU, MEGA_REDU). • How do “REDUs” ensembles rank with respect to EPS, MOGREPS, MINI-MIX, MEGA-MIX? • Where do the best (and the worst) elements of REDU ensembles come from? • How do they score depending on their “origin”? • BEFORE DOWNSCALING: is there added value with respect to single-model ensemble? Strategy A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  9. finish by March 2010 Future plans Future future plans • Implement dynamical downscaling: nest COSMO model in the selected RMs and generate “hybrid” COSMO-LEPS using boundaries from members of different global ensembles. • For a number of case, compare operational COSMO-LEPS and “hybrid” COSMO-LEPS. A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  10. Thank you ! A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  11. Operational set-up Additional products: • 1 deterministic run (ICs and 3-hourly BCs from the high-resolution deterministic ECMWF forecast) to “join” deterministic and probabilistic approaches: start at 12UTC; t = 132h; • 1 hindcast (or proxy) run (ICs and 3-hourly BCs from ECMWF analyses) to “downscale” ECMWF information: start at 00UTC; t = 36h. Core products: 16 perturbed COSMO-model runs (ICs and 3-hourly BCs from 16 EPS members) to generate, “via weights”, probabilistic output: start at 12UTC; t = 132h; A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  12. 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 6 months (March-August 2007).  difficult to draw general conclusions A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  13. 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: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  14. Overestimation of Td2m and soil moisture (1) • Verification period: MAM07 and MAM08. • Obs: synop reports (about 470 stations x day). • Region: 43-50N, 2-18E (MAP D-PHASE area). • Larger bias and larger rmse in MAM08 rather than in MAM07 for COSMO-LEPS deterministic run (in 2007, no multi-layer soil model). A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  15. Main results • COSMO-LEPS system runs on a daily basis since November 2002 (6 “failures” in almost 6 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), scientific experiments (e.g. COPS, MAP D-PHASE, EFAS) 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); • some deficiency in the skill of the system were identified after the system upgrades occurred on Feb 2006 (from 10 to 16 members; from 32 to 40 ML + EPS upgrade!!!), but scores are encouraging throughout 2007 and, to a certain extent, 2008. • 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: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  16. 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: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  17. 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: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

  18. 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? It was developed to combine the advantages of global-model ensembles with the high-resolution details gained by the LAMs, so as to identify the possible occurrence of severe and localised weather events (heavy rainfall, strong winds, temperature anomalies, snowfall, …) generation of COSMO-LEPS to improve the Late-Short (48hr) to Early-Medium (132hr) range forecast of severe weather events. A.Montani; The COSMO-LEPS system: present status and outlook COSMO meeting, Offenbach, 7-11 September 2009

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