engleski

Influence of the assimilation system at DHMZ to forecast of the 2 m parameters

A short description of the local assimilation system setup for a limited area model ALADIN (Aire Limitee Adaptation Dynamique developement InterNational) is given. The assimilation system at DHMZ (Meteorological and Hydrological Service of Croatia) consists of the two parts: the surface assimilation, which is used to change the state of the modeled land surface variables, and the upper air assimilation, which changes the upper air model fields. The surface assimilation is performed by the optimal interpolation (OI) technique, while the upper air assimilation is conducted using the 3D Variational technique (3DVAR). Surface assimilation uses 2 m temperature and relative humidity observations. For upper air assimilation following observations were used: SYNOP, TEMP, AIREP, wind-profiler and measurements from polar and geostationary satellites. During the period from spring 2010 to autumn 2011 assimilation was tested in the parallel suite. Verification of the 2 m parameters will be presented for forecasts with initial and lateral boundary conditions specified from i) the global model ARPEGE (Action de Recherche Petite Echelle Grande Echelle) and ii) the mesoscale assimilation system. Verification results of the near-surface parameters show general improvement when forecasts are initiated from the mesoscale model analysis for almost the entire period.

data assimilation; surface parameters; operational forecast

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