Mesan, an operational mesoscale analysis system

A system for mesoscale analyses of selected variables has been developed. The analysed parametersare of general interest in operational weather forecasting, but normally not availablefrom NWP systems, or available, but with a significantly lower quality than achieved by themesoscale analysis system. A supplementary objective is to produce initial information to beused for now-casting techniques. Examples of parameters are precipitation, temperature, humidity, visibility, wind and clouds. The basis of the analysis system is the optimal interpolationtechnique (OI). The use of observations from automatic stations, radars and satellites havebeen investigated. The investigation indicates that a dense network of ordinary precipitationgauge measurements can produce more accurate analyses than more elaborate systems likeradar that suffers from anomalous echoes and other errors.