Mesan, an operational mesoscale analysis system

A system for mesoscale analyses of selected variables has been developed. T he analysed parameters are of general interest in operational weather forec asting, but normally not available from NWP systems, or available, but with a significantly lower quality than achieved by the mesoscale analysis syst em. A supplementary objective is to produce initial information to be used for now-casting techniques. Examples of parameters are precipitation, tempe rature, humidity, visibility, wind and clouds. The basis of the analysis sy stem is the optimal interpolation technique (OI). The use of observations f rom automatic stations, radars and satellites have been investigated. The i nvestigation indicates that a dense network of ordinary precipitation gauge measurements can produce more accurate analyses than more elaborate system s like radar that suffers from anomalous echoes and other errors.