A.Montani; The COSMO-LEPS system. Recent developments and plans for the COSMO-LEPS system Andrea Montani, C. Marsigli, T. Paccagnella ARPA-SIMC HydroMeteoClimate

A.Montani; The COSMO-LEPS system.

Recent developments and plans for the

COSMO-LEPS system

Andrea Montani,

C. Marsigli, T. Paccagnella

ARPA-SIMC

HydroMeteoClimate Regional Service of Emilia-Romagna, Bologna,

Italy

COSMO General meetingLugano, 10-13 September 2012


Outline

• Recent upgrades of COSMO-LEPS: implementation of 00UTC COSMO-LEPS, modifications in the set-up of members’ perturbations, implementation of calibrated precipitation.

• Performance of the system: time-series verification of COSMO-LEPS using SYNOP, case study assessment (“nevone 2012”).

• Present/future work:modifications to the clustering/selection technique,first tests of COSMO-HYBrid-EPS.

• Summary and plans


Main changes during the COSMO year (1)

• 30 November 2011, COSMO-LEPS “doubles”:

• a new ECMWF time-critical application was prepared and sent to ECMWF as for the implementation of COSMO-LEPS also at 00UTC (cleps00);

• cleps00 and cleps12 have identical configurations (use of COSMO-EU analysis fields also for cleps00 since 18 January 2012);

• cleps00 is potentially more exposed to product delays because of ECMWF system sessions (never happened so far).

• 29 March 2012, no more random choice of the convection scheme:

• following requests of DWD, members 1-8 use Tiedtke convection scheme, members 9-16 use Kain-Fritsch.

• 3 July 2012, system upgrades:

• COSMO model upgraded to 4.21 + perturbation tuning;

• generation of calibrated 24-h TP over Germany, Switzerland, Emilia-Romagna;

• archive of ECMWF-EPS model level fields at 0.25x0.25 on a large domain to enable reruns (last 3 months).


COSMO-LEPS suite @ ECMWF: present status

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

16 Representative Members driving the 16

COSMO-model integrations (weighted according to the cluster

populations)

using either Tiedtke or Kain-Fritsch convection scheme (members 1-8 T,

members 9-16 KF) +

perturbations in turbulence scheme and

in physical parameterisations

COSMO-LEPS

clustering area

• suite runs twice a day (00 and 12UTC) as a “time-critical application” managed by ARPA-SIMC;

• Δx ~ 7 km; 40 ML; fc+132h;• COSM0 v4.21 since July 2012;• computer time (30 million

BUs for 2012) provided by the ECMWF member states in COSMO.

COSMO-LEPS

Integration Domain


Outline

• Performance of the system: time-series verification of COSMO-LEPS using SYNOP; case study assessment (“nevone 2012”).


– 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 2012;

region: 43-50N, 2-18E (MAP D-PHASEPHASE

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


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.

Highest scores in the second part of 2011 for all but the highest threshold.

fc 30-42h: ROC area is low for the highest threshold for last winter; then recovery.

fc 78-90h: in the last months, some recovery of the score for the 15mm threshold, after a “difficult” beginning of the year.

Limited loss of predictability with increasing forecast range.


Heavy snowfalls in Emilia-Romagna (31/1 – 5/2/2012)


COSMO-I7 of 30/01/2012 12UTC (+36-60h)+36-60h

Snow observed (cm) over the 24-hour period ending at 00UTC of 2/2/2012

forecasts (mm of equivalent water!)


COSMO-LEPS of 30/01/2012 12UTC (+36-60h)

available at 23.30 UTC


COSMO-LEPS of 30/01/2012 12UTC (+36-60h)

COSMO-LEPS forecasts give early indication of possible heavy snowfall over the plain.COSMO-LEPS signal remained more stable and consistent than COSMO-I7.


Outline

• Present/future work:modifications to the clustering/selection technique,first tests of COSMO-HYBEPS.


Test modifications of clustering methodology

• Consider distances between ECMWF EPS members according to “COSMO-LEPS metric” (Z, U, V, Q in the mid-lower troposphere over the clustering domain).

• Look at distances between pairs of ECMWF EPS members; to what extent do these distances grow with forecast range (in “COSMO-LEPS metric”)?

• Study a number of seasons.

Outcome: modifications to the number of clusters / number of global EPSs considered / clustering intervals.


COSMO-HYBrid Ensemble Prediction System

From the results of CONSENS PP, come to a synthesis with the different ensemble systems / strategies, considering scientific, implementation, solidity aspects.

Generate 20-member hybrid ensemble (COSMO-HYBrid-EPS), where:

a) 16 members comes from COSMO-LEPS,

b) 1 member is nested on IFS (with Tiedtke scheme),

c) 1 member is nested on IFS (with Kain-Fritsch scheme),

d) 1 member is nested on GME,

e) 1 member is nested on GFS.already existing from CONSENS.

All members have Δx ~ 7 km; 40 ML; fc+132h.

Study performance of different members’ combinations with the same ensemble size.

“20-members esuite” implemented on 7/9/2012;

will be run up to the end of the year.


Main results

Time-series verification:ECMWF EPS changed substantially in the last years (more and more weight to EDA-

based perturbations) and it is hard to disentangle improvements related to COSMO-

LEPS upgrades from those due to better boundaries; nevertheless:– highest values of BSS and ROC area for the probabilistic prediction of 12-h precipitation

for autumn 2011;

– poor performance in the first months of 2012, then recovery. Need to investigate what

happened.

Case-study verification:consistent signal of high-impact weather events for the snowfalls of February 2012.

Other achievements:• provision of ICs and BCs for convective-permitting ensembles;

• operational dissemination implemented for Romania;

• reorganisation of post-processing with Fieldextra.


• Test modifications to the clustering methodology.

• Test COSMO-HYBrid-EPS.• Increase vertical resolution? ensemble size? ... tonight’s discussion.

• LAMEPS_BC project consider possible modifications to COSMO-LEPS suite.

• COSMO-LEPS for TIGGE-LAM (GRIB2 encoding).

• COSMO-LEPS twice a day: generate probabilistic products from lagged ensembles.

Future plans

• Support calibration and verification ( Versus?).

• Carry on collaboration within research project (HyMeX, EFAS, SAFEWIND,

IMPRINTS, …).


Thank you !

Documents

A.Montani; The COSMO-LEPS system. Recent developments and plans for the COSMO-LEPS system Andrea Montani, C. Marsigli, T. Paccagnella ARPA-SIMC HydroMeteoClimate