COSMO-LEPS is the Limited Area Ensemble Prediciton System developed within COSMO consortium in order to
improve the short-to-medium range forecast of extreme and localised weather events.
It is made up of 16 integrations of COSMO model, which is nested on selected members of ECMWF EPS.
COSMO- LEPS started to run on an experimental-operatonal basis on November 2002 and, in November 2005,
it became an ECMWF member-state time-critical application, managed by ARPA-SIM.
COSMO-LEPS runs on a daily basis using a 10 km grid spacing and 40 vertical layers, starting at 12UTC and with a forecast range of 132 hours. The computer time to run the system at ECMWF is provided by a joint account, with the contributions of the COSMO countries which are also ECMWF member state (namely, Greece, Germany, Italy and Switzerland).
The rotated lat-lon coordinates of the lower left and upper right corner of the integration domain are lon=-12.5o, lat=-16.0o and lon=14.95o, lat=7.13o, respectively. The following figure shows the orography (height in m) of the COSMO-LEPS integration domain used.
Fig. 1: The Cosmo domain used for the COSMO LEPS (enlarge)
Since 1 December 2007, the following changes were implemented in the operational suite:
Since September 2003, a 10-member suite is being experimented. In addition to the 5 Cosmo integrations with the operational convection scheme ("Tiedtke runs"), 5 more runs are performed using the recently-implemented Kain-Fritsch convection scheme ("KF runs"). In order to minimize modifications to the operational suite and to test properly the impact of the new scheme, the 5 KF integrations use the same boundary and initial conditions as the Tiedtke runs. Rainfall probability maps using the 10-member suite are being produced and disseminated in addition to the operational ones. The skill of the KF runs as well as the usefulness of a 10-member suite will be evaluated during 2004.
Two test suites started on 1/10/2003 to assess the impact of the clustering-selection technique when either the most recent EPS or the two most recent EPSs are used to select the representative members (when compared to the operational suite when 3 successive EPS sets are employed). The verification will be performed only on EPS runs by assessing the performance of the "reduced" EPS, that is the 5-member EPS obtained after the clustering-selection technique.
COSMO-LEPS application starts at about 20.50 UTC, once the ECMWF EPS starting at 12UTC has passed fc+144h forecast range. Products are disseminated to Met Ops rooms of COSMO weather offices starting from 23.00UTC.
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