Data Assimilation and Mesoscale Weather Prediction: A Study with a Forecast Model for the Alpine Region

A scheme based on the nudging method (Newtonian relaxation) is developed for direct assimiiation of rawinsonde and screen-level data into a mesoscale model for the Alpine region. It is applied to routine observations in various meteorological situations to examine its potenüal capabilitles and limitaüons for numericai weather prediction (NWP) purposes. Aspects of primary interest are the impact of different data, the influence of steep orography particularly with low stratus, and the beneßt from the nudging for mixed-layer Simulation in typical summertime smog conditions.