1. A.Montani; The COSMO-LEPS system. COSMO-LEPS: present status and developments Andrea Montani, D. Cesari, C. Marsigli, T. Paccagnella ARPA-SIMC HydroMeteoClimate Regional Service of Emilia-Romagna, Bologna, Italy XIII COSMO General meeting Rome, 5-8 September 2011

2. A.Montani; The COSMO-LEPS system. Outline Recent upgrades of COSMO-LEPS:  use of soil-moisture analysis fields from COSMO-EU; Performance of the system:  time-series verification of COSMO-LEPS using SYNOP; Implementation of 00UTC COSMO-LEPS:  present situation and future developments; Implementation of SOCHMEL (“Sochi ensemble”). Work for LAMEPS_BC project. Modifications to the clustering/selection technique. Summary and plans.

3. A.Montani; The COSMO-LEPS system. COSMO-LEPS suite @ ECMWF: present status d-1 dd+5 d+1d+2 d+4d+3 older EPS younger EPS clustering period 00 12 Cluster Analysis and RM identification 4 variables Z U V Q 3 levels 500 700 850 hPa 2 time steps Cluster Analysis and RM identification European area Complete Linkage 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 and in physical parameterisations COSMO- LEPS clustering area suite runs as a “time-critical application” managed by ARPA- SIMC; Δx ~ 7 km; 40 ML; fc+132h; COSM0 v4.12 since July 2010; computer time (20 million BUs for 2011) provided by the COSMO partners which are ECMWF member states. COSMO- LEPS Integratio n Domain

4. A.Montani; The COSMO-LEPS system. Types of perturbations As for types and values, the results from CSPERT experimentation were followed (* denotes default values for COSMO v4.12 ): convection_scheme (either Tiedtke* of Kain-Fritsch), tur_len (either 150, or 500*, or 1000), pat_len (either 500*, or 2000), crsmin (either 50, or 150*, or 200), rat_sea (either 1, or 20*, or 40), rlam_heat (either 0.1, or 1*, or 5), mu_rain (either 0.5* or 0), cloud_num (either 5x10^8* or 5x10^7).

5. convection scheme: T=Tiedtke KF=Kain-Fritsch; tur_len: maximal turbulent length scale (default 500m); this parameter is used mainly in the calculation of the characteristic length scale for vertical mixing and thus into the calculation of the vertical transport momentum coefficient; pat_len: length scale of thermal surface patterns (default 500m); this parameter is mainly used in the calculation of the large-scale part of the equation addressing the heat flux parameterisation; horizontal length; rlam_heat: scaling factor of the laminar layer depth (default 1); it defines the layer with non- turbulent characteristics (molecular diffusion effects only); rat_sea: ratio of laminar scaling factors for heat over sea (default 20); crsmin: minimal stomata resistance (default 150); Cloud_num: Cloud droplet number concentration; Mu_rain: Exponent of the raindrop size distribution; ( gscp: Switch on/off of the graupel scheme).

6. A.Montani; The COSMO-LEPS system. Outline Recent upgrades of COSMO-LEPS:  use of soil-moisture analysis fields from COSMO-EU;

7. A.Montani; The COSMO-LEPS system. Upgrades during the “COSMO year” 9 November 2010:  the deterministic run (LMDET) takes the ICs from the soil fields provided by the proxy-run mixed with some ECMWF fields (soil-proxy);  COSMO-LEPS output (up to fc+60h; last 3 months) is saved on ML to enable further downscaling; 11 April 2011:  COSMO-LEPS members use, as ICs, the soil fields provided by COSMO-EU (soil-merge);  perturbation values are tuned and new perturbations are introduced;  upgrade of INT2LM to version 1.18 (with grib_api). 5 July 2011:  ECMWF EPS members are saved on ML over a large domain to enable reruns (last 3 months). No upgrades of COSMO since July 2010 (using model version 4.12)

8. A.Montani; The COSMO-LEPS system. Oper system (interp)  x = 7 km fcst range = 132h initial conditions: interpolated from EPS members; perturbations: type of convection scheme; tur_len; pat_len; crsmin; rat_sea; rlam_heat. COSMO-LEPS with soil-moisture fields from COSMO-EU Test system (merge)  x = 7 km fcst range = 48h initial conditions: interpolated from EPS members merged with surface and soil-layer fields from COSMO-EU (T_SO, W_SO, W_ICE, W_I, FRESHSNW, RHO_SNOW, W_SNOW, T_SNOW). perturbations: type of convection scheme; tur_len; pat_len; crsmin; rat_sea; rlam_heat; mu_rain; cloud_num. “Oper” and “Test” were run in parallel from 1/12/2010 to 15/3/2011 (> 100 cases).

9. A.Montani; The COSMO-LEPS system. BIAS of T2M Ensemble Mean  bias computed over 3 different domains for the period 1/12/2010  15/3/2011 (> 100 cases). —— oper (interp) —— test (merge) T2m forecasts are corrected with height fulldom (~1400 synop)mapdom (~410 synop) mapdom < 100m (~50 synop)  Bias closer to zero for “test” ensemble, which uses the soil moisture fields from COSMO-EU.  Smaller amplitude in bias oscillations for “test”.  fulldom and mapdom: the improvement is systematic for all forecast ranges; the cold bias of “oper” is reduced.  mapdom < 100m: large reduction of bias for day-time verification; increase of the bias for night-time verification.

10. A.Montani; The COSMO-LEPS system. MAE of T2M Ensemble Mean  mae computed over 3 different domains for the period 1/12/2010  15/3/2011 (> 100 cases).  Lower mae for “test” ensemble, which uses the soil moisture fields from COSMO-EU.  fulldom and mapdom: the improvement is systematic for all forecast ranges, especially for day-time verification.  mapdom < 100m: reduction of mae for day-time verification. —— oper (interp) —— test (merge) fulldom (~1400 synop) mapdom (~410 synop) mapdom < 100m (~50 synop) T2m forecasts are corrected with height

11. A.Montani; The COSMO-LEPS system. BIAS of TD2M Ensemble Mean  bias computed over 3 different domains for the period 1/12/2010  15/3/2011 (> 100 cases). —— oper (interp) —— test (merge)  Bias slightly closer to zero for “test” ensemble, which uses the soil moisture fields from COSMO-EU.  fulldom and mapdom: the impact is small, but positive.  mapdom < 100m: the “dry” bias in low-level stations is reduced for all forecast ranges. fulldom (~1400 synop) mapdom < 100m (~50 synop) mapdom (~410 synop)

12. A.Montani; The COSMO-LEPS system. MAE of TD2M Ensemble Mean  mae computed over 3 different domains for the period 1/12/2010  15/3/2011 (> 100 cases).  Lower mae for “test” ensemble, which uses the soil moisture fields from COSMO-EU.  fulldom and mapdom: the mae reduction is small, but systematic and lasts for about 2 forecast days.  mapdom < 100m: the mae reduction is more evident. —— oper (interp) —— test (merge) fulldom (~1400 synop) mapdom (~410 synop) mapdom < 100m (~50 synop)

13. A.Montani; The COSMO-LEPS system. Summary of results for soil-merge experiments  T2M and TD2M: reduction of bias and mean-absolute error if the COSMO-LEPS members take the initial conditions from the soil moisture fields provided by COSMO-EU; the improvement is confirmed over larger and smaller domains; the reduction of errors lasts for more than 2 forecast days;  TOT_PREC: the impact is neutral (not shown). Soil-merge was successfully implemented in the operational COSMO-LEPS suite on 11 April 2011 (… and no problems since then!) the transfer of SMA files from DWD to ECMWF is solid and timely. +

14. A.Montani; The COSMO-LEPS system. Outline Performance of the system:  time-series verification of COSMO-LEPS using SYNOP ;

15. A.Montani; The COSMO-LEPS system. –SYNOP on the GTS Time-series verification of COSMO-LEPS Main features: variable: 12h cumulated precip (18-06, 06-18 UTC); period : from Dec 2002 to Jul 2011; PHASE region: 43-50N, 2-18E (MAP D-PHASE area); method: nearest grid point; no-weighted fcst; obs: synop reports (about 470 stations/day); fcst ranges: 6-18h, 18-30h, …, 102-114h, 114-126h; thresholds: 1, 5, 10, 15, 25, 50 mm/12h; system: COSMO-LEPS; scores: ROC area, BSS, RPSS, Outliers, … both monthly and seasonal scores were computed

16. A.Montani; The COSMO-LEPS system. Time series of ROC area  Area under the curve in the HIT rate vs FAR diagram; the higher, the better …  Valuable forecast systems have ROC area values > 0.6.  Improvement of skill detectable during 2010 and 2011 for all but the highest threshold.  In 2011, few events with heavy precipitation: possible lack of significance of the results for the 15mm threshold.  Limited loss of predictability with increasing forecast range.  fc 30-42h: ROC area is low for the 15mm threshold: WHY?  fc 78-90h: in the last months, ROC area values have shown little dependence on the threshold.

17. A.Montani; The COSMO-LEPS system. Seasonal scores of ROC area: the last 4 springs  Fixed event (“12h precip > 5mm”): consider the performance of the system for increasing forecast ranges.  Fixed forecast range (fc 30-42h): consider the performance of the system for increasing thresholds.  Valuable forecast systems have ROC area values > 0.6.  Need to take into account the different statistics for each season (last MAM was the driest).  Best performance for the spring 2011 (with a good advantage), for all forecast ranges and thresholds.  Similar results for longer forecast ranges or higher thresholds (not shown).

18. A.Montani; The COSMO-LEPS system. 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 the last 4 winters.  Evident seasonal cycle (more outliers in winter).  Overall reduction of outliers in the years up to 2007; then, again in 2009 and 2010, but not in 2011.  Need to take into account the different statistics for each season.  In the short range, best results for last winter.  For longer ranges, the performance of the system is “stable”.  Outliers before 10% from day 2 onwards.

19. A.Montani; The COSMO-LEPS system. Time series of Brier Skill Score  BSS is written as 1-BS/BS ref. 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.  BS equivalent to MSE for deterministic forecast.  fc 30-42h: very good scores in 2010 and 2011; BSS positive for all thresholds since April 2009; fewer and fewer problems with high thresholds.  fc 78-90h: good trend in 2010 and 2011 for all thresholds.  In the last months, “spread” in BSS values for the different threshold values, possibly due to the lack of events. Month-to-month variability is higher than for the ROC area.

20. A.Montani; The COSMO-LEPS system. Seasonal scores of BSS: the last 4 winters  Fixed event (“12h precip > 10mm”): consider the performance of the system for increasing forecast ranges.  Fixed forecast range (fc 30-42h): consider the performance of the system for increasing thresholds.  Need to take into account the different statistics for each season (last DJF was the driest).  Fixed event: best performance for the last two winters (ECMWF EPS had a record performance for winter 2009-2010): BSS positive for all forecast ranges.  Fixed forecast range: similar results as before.  Similar results for longer forecast ranges and for higher thresholds.

21. A.Montani; The COSMO-LEPS system. Ranked Probability Skill Score: time series + seasonal scores  A sort of BSS “cumulated” over all thresholds. RPSS is written as 1-RPS/RPS ref. Sample climate is the reference system. RPS is the extension of the Brier Score to the multi-event situation.  Useful forecast systems for RPSS > 0.  Performance of the system assessed as time series and for the last 4 springs (MAM).  the increase of the COSMO-LEPS skill is detectable for 3 out of 4 forecast ranges along the years;  RPSS positive for all forecast ranges since May 2008; encouraging trend in the last year.  Good results for MAM 2011 (12h-cycle of the score).

22. A.Montani; The COSMO-LEPS system. Outline Implementation of 00UTC COSMO-LEPS;  present situation and future developments;

23. A.Montani; The COSMO-LEPS system. COSMO-LEPS @ 00UTC Background : Due to the increasing use and interest in COSMO-LEPS products, a new ECMWF time- critical application was prepared and sent to ECMWF as for the implementation of COSMO-LEPS also at 00UTC (cleps00). Main features: same configuration as present cleps12 (modify cluster analysis??); post-processing will be done using Fieldextra; cleps00 will run in the late morning, interacting with ECMWF system sessions  product delivery might be occasionally delayed a few hours. Present situation: depending on ECMWF comments/suggestions, cleps00 could be implemented by the end of 2011 (test products should be available earlier!).

24. A.Montani; The COSMO-LEPS system. Implementation of SOCHMEL (“Sochi ensemble”); Outline Sochi (RU) Rome (I)

25. A.Montani; The COSMO-LEPS system. SOCHMEL (SOCHi-targeted Mesoscale EnsembLe system) 1)Next Olympics and Paralympics Winter Games will take place in Sochi, Russia (7-23 February and 7-16 March 2014). 2)For this event, WMO launched a WWRP RDP/FDP initiative, named FROST- 2014 (Forecasting and Research: the Olympic Sochi Testbed)???????? 3)COSMO will perform a number of activities related to Sochi-2014 WWRP RDP/FDP: a)deterministic forecasting, b)probabilistic forecasting: b1) FDP initiatives (“ clone” of COSMO-LEPS over the Sochi area), b2) RDP initiatives (development of a COSMO LAM-EPS system for the Sochi area). c)post-processing and product generation, d)verification.

26. A.Montani; The COSMO-LEPS system. FDP (Forecast Demonstration Project) initiatives SOCHMEL7: limited-area ensemble system based on COSMO (“relocation” of COSMO-LEPS) Horizontal resoluzion: 7 km. Vertical resolution: 40 model levels. Forecast range: 72 hours. Starting time: 00UTC, 12UTC. Ensemble size: 10 members. Boundary conditions: from selected ECMWF EPS members. Initial conditions: interpolated from ECMWF EPS members. Timetable Pre-trial: 2011/12 winter Trial: 2012/13 winter Olympics: 2014 winter.

27. A.Montani; The COSMO-LEPS system. SOCHMEL suite @ ECMWF: present status d+3dd+2d+1 ECMWF EPS clustering interval Cluster Analysis and RM identification 4 variables Z U V Q 3 levels 500 700 850 hPa 2 time steps Cluster Analysis and RM identification Black-Sea area Complete Linkage 10 Representative Members driving the 10 COSMO-model integrations (weighted according to the cluster populations) employing either Tiedtke or Kain-Fristch convection scheme (randomly choosen) + perturbations in turbulence scheme and in physical parameterisations SOCHMEL clustering area Δx ~ 7 km; 40 ML; fc+72h; initial time: 00UTC, 12UTC; for the moment, computer time (10 million BU for 2012) provided by an ECMWF Special Project; suite managed by ARPA-SIMC; contributions from ECMWF member states could be needed in the future. SOCHMEL Integration Domain As for the future, apply for an ECMWF time-critical application

28. A.Montani; The COSMO-LEPS system. RDP (Research and Development Project) initiatives SOCHMEL28: convective-resolving ensemble system Horizontal resoluzion: 2.8 km. Vertical resolution: 50 model levels. Forecast range: 48 hours. Starting time: 00UTC, 12UTC. Ensemble size: 5 members. Boundary conditions: from SOCHMEL7 or from deterministic systems. Initial conditions: from SOCHMEL7 or from deterministic systems. Data assimilation: ??? More details in the plenary talk

29. A.Montani; The COSMO-LEPS system. Outline Work for LAMEPS_BC project;

30. A.Montani; The COSMO-LEPS system. LAMEPS_BC project: background Aim: generation of EPS boundary conditions (at 6 and 18 UTC) for use of LAMEPS community Preliminary issue: to make progress in terms of increasing the efficiency of archiving and retrieving EPS data. The solution: to archive the data on the native reduced Gaussian grid of the ECMWF IFS, but only in a region of interest over the Northern Atlantic and Europe (a bitmap mask is applied so that only data in the masked region are coded in GRIB). The next step: to check if the regionally archived EPS data can be used by the LAMEPS groups.

31. A.Montani; The COSMO-LEPS system. LAMEPS_BC project: present situation 1)For one case study, ECMWF fields were archived both globally (as generated by the operational EPS) and regionally (data are on a reduced gaussian grid N320 for all fields). 2)LAMEPS groups are running their LAMEPS systems taking the boundary conditions from both experiments and comparing the forecasts. 3)As for COSMO-LEPS, cleps_g takes the globally-archived boundaries; cleps_r takes the regionally-archived boundaries: a)upper-level fields: no differences are found for between cleps_g and cleps_r; b)surface fields (2-metre temperature and precipitation): a few differences are found between cleps_g and cleps_r; differences are confined to very few grid points, but are not negligible. Further investigation is in progress. For problems relative to ECMWF data, contact M. Leutbecher.

32. A.Montani; The COSMO-LEPS system. Outline Modifications to the clustering/selection technique.

33. A.Montani; The COSMO-LEPS system. Test modifications of clustering methodologies always select control runs by ECMWF EPS: a new 16-member ensemble (ctrl-LEPS) was created by taking the first 14 members from COSMO-LEPS and adding 2 more members nested on 00UTC and 12UTC the EPS control members; ctrl-LEPS was compared to COSMO-LEPS for 3 months; as for precipitation forecasts, the two systems have identical performance; further investigation is needed to assess spread/skill relationship of both systems. consider shorter forecast ranges for clustering intervals (e.g.: 48- 72h, 72-96h); select the Representative Members from only one EPS: could be strategic in view of having COSMO-LEPS at both 00 and 12UTC.

34. A.Montani; The COSMO-LEPS system. Outline Summary and plans.

35. A.Montani; The COSMO-LEPS system. Main results Operational implementation of the soil-merge This should guarantee lower bias and mae for both T2M and TD2M in short range COSMO-LEPS forecasts. Time-series verification ECMWF EPS changed substantially in the last year (introduction of EDA-based perturbations) and it is hard to disentangle improvements related to COSMO-LEPS upgrades from those due to better boundaries; nevertheless: –high values of BSS and ROC area for the probabilistic prediction of 12-h precipitation, –lower outliers.

36. A.Montani; The COSMO-LEPS system. Study in more detail the impact of the “new” ECMWF EPS on COSMO-LEPS. Develop new products for users (don’t keep them waiting for too long!), using Fieldextra as much as possible. Test modifications to the clustering methodology. Increase vertical resolution (40  50 ML)? COSMO-LEPS@ 00UTC: implement it, finish it, put it operational; then, think about generation of products from lagged ensembles. SOCHMEL: have a first prototype (inclusive of post-processing and dissemination) by December  for the future, need of computer time from COSMO countries! LAMEPS_BC project  consider possible modifications to COSMO-LEPS suite. COSMO-LEPS for TIGGE-LAM (GRIB2 encoding). Future plans Support calibration and verification. Carry on collaboration within research project (e.g. EFAS, SAFEWIND, IMPRINTS, NURC, …).

37. A.Montani; The COSMO-LEPS system. Thank you ! European Conference on Applications of Meteorology / EMS annual meeting 12 – 16 September 2011, Berlin (Germany) Session NWP4: Probabilistic and ensemble weather forecasting applications at short and very short ranges (including nowcasting) http://meetings.copernicus.org/ems2011

38. A.Montani; The COSMO-LEPS system. FROST-2014 vs SOCHMEL 1)Introduction to FROST-2014: a)What is it? b)What has to do with COSMO? 2)COSMO ensemble activities within FROST-2014: a)introduction to SOCHMEL (the SOCHi-targeted Mesoscale EnsembLe system) b)methodology; c)phases of development; d)planned activity. 3)Final remarks.

39. A.Montani; The COSMO-LEPS system. Important ingredients 1.Develop experience with probabilities. 2.Feedback on the top-priority products. 3.Snow analysis. 4.Soil-field initialisation. 5.Observations to assess the quality of the system. 6.Computer time. 7.Timeliness in product delivery. 8.… More details in the plenary talk

40. A.Montani; The COSMO-LEPS system. Test data for LAMEPS Boundary Conditions

41. A.Montani; The COSMO-LEPS system. Proposed region for archiving LAMEPS BC data

42. A.Montani; The COSMO-LEPS system. Outline Introduction:  migration to the 7-km system. COSMO-LEPS 10 km (old) COSMO-LEPS 7 km (new)

43. A.Montani; The COSMO-LEPS system. 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.

44. A.Montani; The COSMO-LEPS system. Operational set-up 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; 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.

45. A.Montani; The COSMO-LEPS system. 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

46. A.Montani; The COSMO-LEPS system. Score dependence on the domain size (2) RPSS  RPSS score… the higher the better… (and positive).  ROC area… the higher the better… (and above 0.6).  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. OUTL ROC  Outliers percentage … the lower the better.

47. A.Montani; The COSMO-LEPS system. Bias and rmse of T2M Ensemble Mean  Consider bias (the closer to zero, the better) and rmse (the lower the better).  Bias closer to zero (0.5 °C of decrease) and lower rmse for the 7-km suite.  The improvement is not “massive”, but detectable for all forecast ranges, especially for day-time verification.  The signal is stable (similar scores for 1-month or 3-month verification).  Need to correct T2M forecasts with height to assess the impact more clearly.

48. A.Montani; The COSMO-LEPS system. Overestimation of Td 2m 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).

49. A.Montani; The COSMO-LEPS system. 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.

50. A.Montani; The COSMO-LEPS system. 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. 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. Time series scores cannot easily disentangle improvements related to COSMO-LEPS itself from those due to better boundaries by ECMWF EPS. 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).

51. A.Montani; The COSMO-LEPS system. COSMO-LEPS 16-MEMBER EPS 51-MEMBER EPS tp > 1mm/24h tp > 5mm/24h Average values (boxes 0.5 x 0.5) MAM06  As regards AVERAGE precipitation above these two threshols, the 3 systems have similar performance.

52. A.Montani; The COSMO-LEPS system. ENSEMBLE SIZE REDUCTION IMPACT EVALUATED ON CASE STUDIES (1)

53. A.Montani; The COSMO-LEPS system. ENSEMBLE SIZE REDUCTION IMPACT EVALUATED ON CASE STUDIES (2) Observed precipitation between 15-11-2002 12UTC and 16-11-2002 12 UTC Piedmont case

54. A.Montani; The COSMO-LEPS system. 2002111212 Piedmont 20 mm150 mm 5 RMs 10 RMs All 51

55. A.Montani; The COSMO-LEPS system. COSMO-LEPS Real time products

56. A.Montani; The COSMO-LEPS system. 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 in forecasting intense and localised events is currently still limited.

57. A.Montani; The COSMO-LEPS system. 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

58. A.Montani; The COSMO-LEPS system. 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

59. A.Montani; The COSMO-LEPS system. 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 OBJECTIVE VERIFICATION OF COSMO-LEPS COSMO observations

60. A.Montani; The COSMO-LEPS system. CLEPSEPS Verification grid OBS MASK

61. A.Montani; The COSMO-LEPS system. COSMO-LEPS 16-MEMBER EPS 51-MEMBER EPS tp > 1mm/24h tp > 5mm/24h Average values boxes 0.5x0.5 deg 3 sis

62. A.Montani; The COSMO-LEPS system. COSMO-LEPS 16-MEMBER EPS tp > 1mm/24h NOCC=610 NOCC=1195 tp > 5mm/24h NOCC=2671 tp > 10mm/24h ave 0.5

63. A.Montani; The COSMO-LEPS system. Maximum values boxes 0.5x0.5 deg tp > 1mm/24h tp > 5mm/24h tp > 10mm/24h COSMO-LEPS 16-MEMBER EPS 51-MEMBER EPS 3 sis

64. A.Montani; The COSMO-LEPS system. COSMO-LEPS 16-MEMBER EPS tp > 20mm/24h NOCC=227 Average values boxes 0.5x0.5 deg

65. A.Montani; The COSMO-LEPS system. COSMO-LEPS NW COSMO-LEPS W tp > 1mm/24h COSMO-LEPS weighting procedure maximum values (boxes 0.5x0.5 deg)

66. A.Montani; The COSMO-LEPS system. 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.

67. A.Montani; The COSMO-LEPS system. 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”.

68. A.Montani; The COSMO-LEPS system. 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.

69. A.Montani; The COSMO-LEPS system. COSMO-LEPS_10 (Old) vs COSMO-LEPS_7 (New) Deterministic verification of T2M ensemble mean  Variable: 2-metre temperature.  Period: from June to November 2009.  Forecast ranges: fc+6h, fc+12h, …, fc+132h.  Scores: root-mean-square error, bias. Probabilistic verification of 12-hour cumulated precipitation  Variable:12h cumulated precipitation (18-06, 06-18 UTC).  Period: from June to November 2009.  Forecast ranges: fc 6-18h, fc 18-30h, …, fc 114-126h.  Scores: ROC area, BSS, RPSS, Outliers.  Thresholds: 1, 5, 10, 15, 25, 50 mm/12h.  Observations: SYNOP reports over either MAP D-PHASE region (450 reports/day) or the FULL-DOMAIN (1400 reports/day).  Method: nearest grid point; no-weighted fcst.

70. A.Montani; The COSMO-LEPS system. Bias and rmse of T2M Ensemble Mean  Consider bias and rmse for 3 months (24/5  24/8/2009) over MAPDOM ( ∼ 450 synop).  T2m forecasts are corrected with height.  Bias closer to zero and lower rmse for the 7-km suite.  Improvement is not “massive”, but detectable for all forecast ranges, especially for day-time verification.  Similar results over MAPDOM and over FULLDOM (not shown).  The signal is stable (same scores also for 6-month verification). ---- OLD rmse (10 km) ---- NEW rmse (7 km) —— OLD bias (10 km) —— NEW bias (7 km)

71. A.Montani; The COSMO-LEPS system. ROC area, BSS for 12-hour tp  Consider the event “10 mm of precipitation in 12 hours” for ROC area and BSS (from Jun to Nov 2009).  Better results for the 7-km suite, both for ROC area and BSS values.  The impact is more evident for BSS.  Reduction of 12-h cycle in 7-km runs.  The improvement is detectable for all forecast ranges and for both MAPDOM and FULLDOM. ROC area (both FULLDOM and MAPDOM)BSS (both FULLDOM and MAPDOM)

72. A.Montani; The COSMO-LEPS system. COSMO-LEPS_10 (Old) vs COSMO-LEPS_7 (New) Deterministic verification of T2M ensemble mean  Variable: 2-metre temperature.  Period: from June to November 2009.  Forecast ranges: fc+6h, fc+12h, …, fc+132h.  Scores: root-mean-square error, bias. Probabilistic verification of 12-hour cumulated precipitation  Variable:12h cumulated precipitation (18-06, 06-18 UTC).  Period: from June to November 2009.  Forecast ranges: fc 6-18h, fc 18-30h, …, fc 114-126h.  Scores: ROC area, BSS, RPSS, Outliers.  Thresholds: 1, 5, 10, 15, 25, 50 mm/12h.  Observations: SYNOP reports over either MAP D-PHASE region (450 reports/day) or the FULL-DOMAIN (1400 reports/day).  Method: nearest grid point; no-weighted fcst.

73. A.Montani; The COSMO-LEPS system. COSMO-LEPS (developed at ARPA-SIMC) 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, including Germany, Greece, Italy, Poland, Romania, Russia, 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 high- impact and localised weather events (heavy rainfall, strong winds, temperature anomalies, snowfall, …)  generation of COSMO-LEPS to improve the forecast of high-impact weather in the short and early-medium range (up to fc+132h)

74. A.Montani; The COSMO-LEPS system. Dim 2 Initial conditions Dim 1 Dim 2 Possible evolution scenarios Dim 1 Initial conditions ensemble size reduction Cluster members chosen as representative members (RMs) LAM integrations driven by RMs LAM scenario COSMO-LEPS methodology