NUMERICAL SIMULATIONS OF THE ELBE FLOOD CASE: SENSITIVITY TO INITIAL AND BOUNDARY DATA

Numerical experiments with the model chain of the German Weather Service are conducted to find the reasons for the bad performance of the operational precipitation forecast in the case of the Elbe flood in August 2002. The sensitivity to initial and to boundary data as well as to a new precipitation scheme and the horizontal model resolution is inspected. The greatest improvement concerning the amount and location of the predicted precipitation field is achieved by using ECMWF analysis data as initial fields. Also, the implementation of a precipitation scheme that allows the rain to be advected with the wind exhibits a positive effect. Last, the better resolution of the global model improves the rainfall forecast, whereas the better resolution of the regional model produces worse results