INFLUENCE OF ATMOSPHERIC CIRCULATION TYPES ON SPACE-TIME DISTRIBUTIONOF INTENSE RAINFALL

The influence of the prevailing weather situation on the temporal evol ution and geographical distribution of intense rainfall is studied, as a potential tool to improve rainfall prediction. A classification sch eme of the atmospheric circulation over the east Mediterranean territo ry is used for the analysis. The study area is the Sterea Hellas regio n (central Greece) with an area of about 25,000 km(2). Daily data from 71 rain gages and hourly data from three rain recorders over a 20 yea r period are used. From these data sets, the intense rainfall events w ere extracted and analyzed. Several empirical and statistical methods (also including the available tools of a Geographical Information Syst em) are used for the analysis and comparison of rainfall distribution both in time and in space. The analysis shows that the contribution of the concept of weather types to the quantitative point rainfall predi ction in short timescale is small, and only the estimation of the prob ability of occurrence of an intense event is feasible. On the contrary , the relation between the spatial distribution of rainfall and the at mospheric circulation patterns is significant and may be used for impr oving the forecasting of the geographical distribution of rainfall.