The objective weather type classification of the German Weather Service and its possibilities of application to environmental and meteorological investigations

The objective weather type classification of the German weather service and its application possibilities are described. Meteorological criteria for t his classification are the advection of air masses, the cyclonality and the humidity of the troposphere, leading to numerical indices from which the w eather types are derived. The data basis is the numerical weather analysis and forecast system of the German Weather Service. A time series of the wea ther type data covering more than 20 years is available now. The classifica tion area is Germany, in principle it can be transferred to other areas as well. There are 40 different weather types, but the numerical indices provi de the possibility to enlarge or to reduce the number of types without chan ging the meteorological criteria. This makes the classification very flexib le for individual users. Various applications of this weather type classifi cation are listed. A regularly weather type monitoring via INTERNET has bee n realized.