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The COSMO-LEPS system at ECMWF Chiara Marsigli, Andrea Montani, Tiziana Paccagnella ARPA-SIM, Bologna, Italy.

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Presentation on theme: "The COSMO-LEPS system at ECMWF Chiara Marsigli, Andrea Montani, Tiziana Paccagnella ARPA-SIM, Bologna, Italy."— Presentation transcript:

1 The COSMO-LEPS system at ECMWF Chiara Marsigli, Andrea Montani, Tiziana Paccagnella ARPA-SIM, Bologna, Italy

2 Outline The Limited-area Ensemble Prediction System COSMO-LEPS Research priorities and system development LAM ensemble for the short-range: COSMO-SREPS COSMO-LEPS requirements

3 COSMO-LEPS late-short early-medium range (3-5 days) LAM ensemble boundary conditions initial conditions ECMWF EPS downscaling ensemble LM run

4 COSMO-LEPS suite at ECMWF (running from 5/11/2002, new suite from 5/2/2006) d-1d d+5 d+1d+2 d+4d+3 oldest EPS youngest EPS clustering period Cluster Analysis + selection of 16 RMs 4 variables Z U V Q 3 levels hPa 2 time steps European Area Complete Linkage 16 Representative Members driving the 16 Lokal Modell integrations (weighted according to the cluster population) Random choice of the convection scheme (Tiedtke or Kain-Fristch) COSMO- LEPS clustering area suite running daily at ECMWF managed by ARPA-SIM (ECMWF time- critical application); Δx = 10 km - 40 ML; forecast range: 132h; computer time (4 million BU in 2006) provided by the COSMO partners which are ECMWF member states archived on MARS COSMO- LEPS integration domain Recent changes

5 COSMO–LEPS verification (SON 2004) Verification grid COSMO-LEPS (10 km) vs EPS (80 km) over 4500 stations box included in scores if at least 10 obs fall in the box verification of the distributions

6 Average values - boxes 1.5x1.5 deg tp > 10mm/24h COSMO-LEPS 10-MEMBER EPS 51-MEMBER EPS tp > 10mm/24h tp > 20mm/24h

7 Maximum values - boxes 1.5x1.5 deg tp > 10mm/24h tp > 20mm/24h tp > 10mm/24h COSMO-LEPS 10-MEMBER EPS 51-MEMBER EPS

8 COSMO-LEPS box size MED 0.5 MED 1.0 MED 1.5 1mm/24h 10mm/24h 20mm/24h New verification!

9 Research priorities 1. member representativeness in terms of precipitation (weighting problem) 2. addition of model perturbations 3. short-range ensemble => SREPS

10 1. Representativness (weighting problem) no evidence of better scores obtained by the weighted COSMO-LEPS against the not weighted one in terms of precipitation except in a subjective evaluation (ARPAL, D. Sacchetti) problem of representativeness in precipitation? too large clustering area?

11 ARPAL, D. Sacchetti

12 representativness Brute force (51 members) 12/11/2002 (mm) same cluster different clusters

13 islands Compute p1 and p2 percentiles of the whole precipitation field Identify an island starting from a point where p2 is overcome and extending until not going under the p1 value Compute an index defined as I=a*bs+(1-a)*(dpd-1) where bs is the rms distance between the island masks (a field =1 where there is an island and =0 otherwise) and dpd=(p1+p2) mi /(p1+p2) mj

14 ALPINE suite (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). On single events, differences between the 2 suites can be noticeable. Prob maps of 3-day rainfall exceeding 50 and 100 mm (fc24- 96h); forecast starting at UTC Objective verification on-going! opealp

15 NW Europe suite (SPCOWIND billing units) Generation of a new limited-area ensemble forecast system for the prediction of wind and wind gusts over North-Western Europe (EURORISK-PREVIEW project, WINDSTORM) 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

16 2. Addition of model perturbations LAM ensemble boundary conditions initial conditions model (LAM): parameters, schemes, tendencies, surface forcing

17 Parameter list ( COSMO )

18 Test of a perturbed COSMO-LEPS vs operational COSMO-LEPS Operational system (COSMO-LEPS): b.c. and i.c. perturbations from 10 Representative Members selected out of 2 ECMWF EPS; use of Tiedtke or Kain-Fritsch random Perturbed system: addition of perturbations of the parameters of the model physics -> runtime perturbations Forecast range: +72h 10 members 09/04/ UTC

19 clope >10mm/6h >20mm/6h >30mm/6h>40mm/6h

20 clpert >10mm/6h >20mm/6h >30mm/6h>40mm/6h

21 clope >10mm/6h >20mm/6h >30mm/6h>40mm/6h

22 clpert >10mm/6h >20mm/6h >30mm/6h>40mm/6h

23 Spread-skill

24 3. Short-range ensemble (SREPS) test the model perturbations on a short-range limited-area ensemble (same LAM model, same domain) using a multi-model approach for ic and bc if working, use model perturbations also in COSMO-LEPS

25 ic and bc: multi-model approach a MUlti-Model MUlti-Boundaries ensemble is operational at INM (Spain): 4 different limited-area models (HIRLAM, HRM, MM5, UM) are nested on 4 different global models (IFS, GME, AVN, UM) => 16 members ensemble (25 km horizontal resolution) from May 2006 LM has been added IFS LM 25km GME LM 25km AVN LM 25 km Courtesy of INM UM LM 25 km

26 COSMO-SREPS (Short-Range Ensemble Prediction System) short range (up to 3 days) 16 LM runs at 10 km LM at 25 km on IFS IFS – ECMWF global by INM Spain LM at 25 km on GME GME – DWD global LM at 25 km on UM UM – UKMO global LM at 25 km on NCEP AVN – NCEP global P1 P2 P3 P4 4 different parameter perturbations (kept fix during the whole integration)

27 ensemble spread 12/05 12UTC 13/05 00UTC 13/05 12UTC

28 Requirements 3-hourly post-processing of ECMWF deterministic run up to fc+144h (like EPS members) so that both the LMDET run and the COSMO-LEPS runs have boundary conditions every 3 h assistance so as to be able to interpolate on a regular lat-lon grid (using MARS at ECMWF) grib files produced on a rotated grid (like the COSMO-LEPS one)


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