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The COSMO-LEPS system: present status and outlook Andrea Montani, Chiara Marsigli and Tiziana Paccagnella ARPA-SIM Hydrometeorological service of Emilia-Romagna, Italy. X General COSMO meeting Cracow,15-19 September 2008. Present status and recent updates Possible changes and future plans. - PowerPoint PPT Presentation
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A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
The COSMO-LEPS system:
present status and outlook
Andrea Montani, Chiara Marsigli and Tiziana Paccagnella
ARPA-SIM
Hydrometeorological service of Emilia-Romagna, Italy
X General COSMO meetingCracow,15-19 September 2008
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Outline
• Present status and recent updates
• Possible changes and future plans
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
The new COSMO-LEPS suite @ ECMWFbefore December 2007
d-1d-1 dd d+5d+5d+1d+1 d+2d+2 d+4d+4d+3d+3
older EPSolder EPS
younger EPSyounger EPS
clustering clustering periodperiod
0000
1212
Cluster Analysis and RM identificationCluster Analysis and RM identification
4 variables4 variables
Z U V QZ U V Q
3 levels3 levels
500 700 850 hPa500 700 850 hPa
2 2 time time stepssteps
Cluster Analysis and RM identificationCluster Analysis and RM identification
European European areaarea
Complete Complete LinkageLinkage
COSMO-LEPS
Integration Domain
1616 Representative Representative Members driving the Members driving the
1616 COSMO-model COSMO-model integrations integrations
(weighted according (weighted according to the cluster to the cluster populations)populations)
employing either employing either Tiedtke or Kain-Tiedtke or Kain-
Fristch convection Fristch convection scheme (randomly scheme (randomly
choosen)choosen)
COSMO-LEPS
clustering area
• 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.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Recent updates (1)
Changes to the operational suite on 1 December 2007:Changes to the operational suite on 1 December 2007:• new model version (COSMO-LM 4.0);• new numerics (Runge-Kutta scheme); • use of multi-layer soil model;• new perturbations introduced relative to the maximal turbulent length scale (tur_len) and
to the length scale of thermal surface patterns (pat_len) to increase spread and maintain skill.
Old system and new system ran in parallel for 52 days (October and November 2007);
Larger T2m spread in new system for all forecast ranges;
Comparable skill (in terms of T2m root-mean-square error) of the two systems.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Recent updates (2)
Since 15/6/2008, JRC has got access to COSMO-LEPS data for the use Since 15/6/2008, JRC has got access to COSMO-LEPS data for the use in the experimental European Flood Alert System (EFAS)in the experimental European Flood Alert System (EFAS)
• In the framework PREVIEW Project (WP: Medium-Range Plain Flood), COSMO-LEPS showed added value for flood forecasting, with respect to ECMWF EPS and varEPS.
COSMO-LEPS will be used, with ECMWF EPS and GME DWD deterministic forecasts, as input to the flood forecasting system over the major European river basins.
success for COSMO both from a scientific and a visibility point of view.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
COSMO-LEPS suite @ ECMWFsince December 2007
d-1d-1 dd d+5d+5d+1d+1 d+2d+2 d+4d+4d+3d+3
older EPSolder EPS
younger EPSyounger EPS
clustering clustering periodperiod
0000
1212
Cluster Analysis and RM identificationCluster Analysis and RM identification
4 variables4 variables
Z U V QZ U V Q
3 levels3 levels
500 700 850 hPa500 700 850 hPa
2 2 time time stepssteps
Cluster Analysis and RM identificationCluster Analysis and RM identification
European European areaarea
Complete Complete LinkageLinkage
COSMO-LEPS
Integration Domain
1616 Representative Representative Members driving the Members driving the 1616
COSMO-model COSMO-model integrations (weighted integrations (weighted according to the cluster according to the cluster
populations)populations)
employing either employing either Tiedtke or Kain-Fristch Tiedtke or Kain-Fristch
convection scheme convection scheme (randomly choosen) (randomly choosen)
++perturbations in perturbations in
turbulence schemeturbulence scheme
COSMO-LEPS
clustering area
• suite runs as a ”time-critical application” managed by ARPA-SIM;
• Δx ~ 10 km; 40 ML; fc+ 132h;• COSM0 v4.0 (with RK + multi-
layer);• computer time (5.8 million
BU for 2008) provided by the COSMO partners which are ECMWF member states.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
but …
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Semi-diurnal cycle in COSMO-LEPS scores
RPSS score for 12-hour cumulated precipitation … the higher the better … Performance of the system assessed for the last 5 summers (JJA) and the last 5 autumns
(SON).
RPSSEvident 12-hour cycle in
RPSS scores (the same holds for BSS, 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 (in summers) and with increasing forecast range.
Bad performance of the system in Summer 2006.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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 outlookCOSMO meeting, Cracow, 15-19 September 2008
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.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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 outlookCOSMO meeting, Cracow, 15-19 September 2008
Overestimation of Td2m and soil moisture (2)
from Andrè Walser
COSMO-LEPS members have higher soil moisture than COSMO-7 run at Meteoswiss (case of 20/7), especially in the Alps.
For the future, do not simply interpolate from ECMWF IFS to COSMO model with the multi-layer soil model.
generate “home-made” soil moisture analysis (from COSMO-EU, from a proxy-run, …)
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
every now and then, “Floating-point exceptions” when the model writes output files over small subdomains …
Model explosion for COSMO-LEPS
Temporarily patch (which works, anyway!):the failed task is resubmitted with half time-step.
A more sophisticated investigation of model explosions will be carried out in the near future.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Feasibility study of COSMOLEPS at 7 km (cleps_7)
Motivations:Provide a more detailed description of
mesoscale processes by incresing the horizontal resolution.
Do not lose a “reasonable advantage” against ECMWF EPS, which will go to x=25 km during 2009.
“Keep the pace” with deterministic model (x~ 2-3 km): if the gap in resolutions between deterministic and probabilistic systems is too large, the two systems go for different solutions (that is, they forecast different weather!).
from 10 to 7 km (plus small domain extensions) does not seem a lot
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
but …
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Present systemx = 10 kmz = 40 MLt = 90 sngp = 306x258x40 =
3.157.920fcst range = 132hcost = 640 BU x runelapsed time = 45 min
COSMO-LEPS at 7 km (cleps_7): the answer to forecasters’ dream?
New systemx = 7 kmz = 40 MLt = 72 sngp = 510x405x40 =
8.262.000fcst range = 132hcost = 1925 BU x runelapsed time = 138 min
… cleps_7 is about 3 times more expensive than the present configuration
new computer at ECMWF being installed
Computer resources for each ECMWF member state will increase by a factor of 5 (five) and ….
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
The dream is possible
COSMO-LEPS 10 kmCOSMO-LEPS 7 km
the grid of cleps_7 would be almost identical to that of COSMO-EU, this making easier and cleaner the use of initial fields provided by DWD (e.g. soil moisture analysis).
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
• tackle the soil moisture deficiency:
– use the soil moisture analysis fields provided by DWD,
– use the fields provided by the “proxy-run”,
• run cleps_7 for ~ 40 days in autumn 2008 and assess the impact;
• within TIGGE-LAM, develop coding of COSMO-LEPS output files in GRIB2 format;
Future plans (2008 and 2009)
• migration to the new machine at ECMWF;
• use a better snow analysis (possibly provided by DWD or Meteoswiss);
• extend the cluster analysis so as to consider not only ECMWF EPS, but also UKMO MOGREPS as global ensemble providing ic’s and bc’s (first tests);
• implementation of cleps_7;
• gaining from COSMO-SREPS experience, introduce more model perturbations;• test COSMO-LEPS nested on the under-development ECMWF EDA during MAP
D‑PHASE period;
• support calibration and verification.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Thank you !
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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).
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
ENSEMBLE SIZE REDUCTIONIMPACT EVALUATED ON CASE STUDIES (1)
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
2003082512 Friuli
(+72-+96)
20 mm 100 mm
5 RMs
10 RMs
All 51
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
2002111212 Piedmont
20 mm 150 mm
5 RMs
10 RMs
All 51
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
COSMO-LEPS
Real time products
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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.
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
CLEPS EPS
Verification grid
OBS MASK
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
COSMO-LEPS
16-MEMBER EPS
51-MEMBER EPS
tp > 1mm/24h
tp > 5mm/24h
Average values boxes 0.5x0.5 deg3 sis
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
COSMO-LEPS
16-MEMBER EPS
tp > 1mm/24h
NOCC=610
NOCC=1195
tp > 5mm/24h
NOCC=2671
tp > 10mm/24h
ave 0.5
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
COSMO-LEPS
16-MEMBER EPS
tp > 20mm/24hNOCC=227
Average values boxes 0.5x0.5 deg
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
COSMO-LEPS NW
COSMO-LEPS W
tp > 1mm/24h
COSMO-LEPS weighting procedure
maximum values (boxes 0.5x0.5 deg)
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
The COSMO-LEPS suite @ ECMWFNovember 2002 – May 2004
d-1d-1 dd d+5d+5d+1d+1 d+2d+2 d+4d+4d+3d+3
oldest EPSoldest EPS
1212
middle EPSmiddle EPS
oldest EPSoldest EPS
youngest EPSyoungest EPS
clustering clustering periodperiod
0000
1212
Cluster Analysis and RM identificationCluster Analysis and RM identification
4 variables4 variables
Z U V QZ U V Q
3 levels3 levels
500 700 850 hPa500 700 850 hPa
2 2 time time stepssteps
Cluster Analysis and RM identificationCluster Analysis and RM identification
European European areaarea
Complete Complete LinkageLinkage
5 Representative 5 Representative MembersMembers
Driving the 5Driving the 5COSMO-model COSMO-model integrationsintegrations
COSMO-LEPS
Integration Domain
COSMO-LEPS
clustering area
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
The COSMO-LEPS suite @ ECMWFJune 2004 – January 2006
d-1d-1 dd d+5d+5d+1d+1 d+2d+2 d+4d+4d+3d+3
middle EPSmiddle EPS
youngest EPSyoungest EPS
clustering clustering periodperiod
0000
1212
Cluster Analysis and RM identificationCluster Analysis and RM identification
4 variables4 variables
Z U V QZ U V Q
3 levels3 levels
500 700 850 hPa500 700 850 hPa
2 2 time time stepssteps
Cluster Analysis and RM identificationCluster Analysis and RM identification
European European areaarea
Complete Complete LinkageLinkage
COSMO-LEPS
Integration Domain
10 10 Representative Representative
MembersMembersdriving the 10driving the 10COSMO-model COSMO-model integrationsintegrations
employing either employing either Tiedtke or Kain-Tiedtke or Kain-Fristch scheme Fristch scheme
randomly randomly choosenchoosen
COSMO-LEPS
clustering area
• Suite running in real time at ECMWF managed by ARPA-SIM;
• Δx ~ 10 km• Fc length: 120h
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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 byRMs
LAM scenario
LAM scenario
LAM scenario
COSMO-LEPS methodologyCOSMO-LEPS methodology
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Time series of Brier Skill ScoreBSS 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 improvement of
performance detectable for all thresholds along the years;
still problems with high thresholds, but good trend in 2007.
fc step: 30-42h
Jun04: 5m 10m
Feb06: 10m16m; 32ML 40 ML
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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.
Jun04: 5m 10m
Feb06: 10m 16m; 32ML 40 ML
fc step: 78-90h
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Time series of ROC areaArea under the curve in the HIT rate vs FAR diagram. Valuable forecast systems have ROC area values > 0.6.
ROC
Jun04: 5m 10m
Feb06: 10m 16m; 32ML 40 ML
fc step: 30-42h
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.
fc step: 78-90h
Jun04: 5m 10m
Feb06: 10m 16m; 32ML 40 ML
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Outliers: time series + seasonal scoresHow 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.
Jun04: 5m 10m Feb06: 10m 16m; 32ML 40 ML
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: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
Outliers: time series + seasonal scoresHow many times the analysis is out of the forecast interval spanned by the ensemble
members. … the lower the better … Performance of the system assessed for 4 different Autumns.
OUTL
Continuous reduction of outliers from one year to the other, also related to the increase of ensemble size (more evident for the 5 to 10 increase, rather than from 10 to 16).
Need to take into account the different statistics for each season (SON 2006 less rainy than the others).
Jun04: 5m 10m Feb06: 10m 16m; 32ML 40 ML
A.Montani; The COSMO-LEPS system: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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: present status and outlookCOSMO meeting, Cracow, 15-19 September 2008
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.
• 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.
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).