SPATIAL AND TEMPORAL VARIABILITY OF EXTREME DAILY PRECIPITATION

Abstract. The aim of this study is to analyze the maximum daily precipitation amounts in Romania for the period 1961-1996. The data were collected from 96 meteorological stations distributed over the entire Romanian territory. The annual maximum of daily precipitation amounts for successive years over the period 1961-1996 and the absolute maximum of the maximum daily precipitation amounts for the period 1961-1996 were determined for each station. A statistical analysis of the annual values of maximum daily precipitation amounts was performed in order to provide their spatial and temporal variability. Various statistical characteristics of maximum daily precipitation amounts during the whole period analyzed, like the annual mean, the standard deviation and the coefficient of linear trend were mapped over Romania. The annual maximum of the daily precipitation amounts series shows mostly a decreasing trend during the analyzed period, but statistically significant trends were found only at a few stations in Romania. The temporal variability and linear trends of maximum daily precipitation amounts were presented for selected Romanian stations. The influence of the atmospheric circulation on the extreme daily precipitation was analyzed by using the large-scale pattern classification expressed by Hess-Brezowsky weather types. The highest daily precipitation amounts occur usually during circulation types with cyclonic centre or cyclonic trough over south-eastern Europe. However, heavy rainfalls may occur over Romania during other situations including those with high pressure