Ensemble Configuration

Ensemble Prediction System COSMO-ME-EPS (Operational since 2014)
The atmospheric short-range ensemble prediction system (COSMO-ME EPS) based on the COMET-LETKF analysis and the COSMO model is running operationally at COMET (pre-operational since July 2013). The relevant characteristics of the atmospheric COSMO-ME EPS are:

• Domain and resolution: COSMO model is integrated 40 times on the same domain of the COMET-LETKF system.
• IC and BC: initial conditions are derived from the COMET-LETKF system; lateral boundaries conditions are from the most recent ECMWF-EPS run.
• Model error: stochastics physics perturbation tendencies.
• Forecast range: 72 hours at 00/12 UTC.

The main features of the operational implementations of the COSMO-ME-EPS are summarized in the following table:

Model	COSMO
Number of ensemble members	40+1
Domain size	779 x 401
Grid spacing	0.0625° (7km)
Number of layers / top	45 / ~22 Km
Time step and integration scheme	60 sec Runge-kutta HE-VI time-splitting
Forecast range/step	72 hrs/3 hrs
Initial time of model run	00/12 UTC
Lateral boundary conditions	most recent ECMWF-EPS
L.B.C. update frequency	3 hrs
Initial state	LETKF analysis
Model Uncertainty Perturbations	"Relaxation-to-prior spread" multiplicative inflation; Additive noise from scaled ECMWF EPS pertubations; Stochastics physics perturbation tendencies
Surface Boundary Perturbations	Climatologically perturbed SST, soil moisture perturbations in progress
ADDITIONAL FEATURES	Provides atmosferic forcing to the NETTUNO-EPS sea state probabilistic model - 3' resolution