Variability of summer-time precipitation in Danube plain, Bulgaria

Over the recent years the climate extremes like as drought and floods become more often and have negative impact on human society. That is way it is very important to know the peculiarities of precipitation variability. The paper investigates precipitation variability during summer time in one of the most important agriculture region in Bulgaria - Danube Plain. The summer-time is determined for the period May - October. The study is based on monthly precipitation total for the period 1961-2005. The precipitation variability is analyzed by comparison with the period 1961-1990, determined by World Meteorological Organization as "contemporary climate". In order to investigate the precipitation variability the various indices lake as Percent of Normal, Rainfall Anomaly Index and Cumulative Anomaly have been calculated. Two wet spells (1865-1983 and 1993-2005) and one dry spell (1983-1993) have been identified. The Kriging interpolation has been applied for presenting special distribution of precipitation variability.