Characteristics and spatial distribution of the atmospheric precipitation in the summer season on the territory of Ukraine and the possibilities of their long-term forecast

Abstract

The long-term variability of atmospheric precipitation in the summer season on the territory of Ukraine was studied with the characteristics of extreme rains and detailing according to the data of the stations of the northern cluster. In general, for the summer season the largest deficit of precipitation is recorded in August (along with a decrease in daily maximums and the number of days with precipitation), and the smallest decrease in precipitation has been registered in June along with an increase in the intensity of daily precipitation. Intraseasonal variability of significant precipitation is detected, and their contribution to the total precipitation amount increased only in June. The number of occurrences of very heavy rain has reached a maximum during 2001-2010 with the highest occurrence in July. In the last decade their number has slightly deteriorated, and the area of coverage has also decreased. Very heavy rains cover an average of 20 regions every year, most characteristic to the south, including the Odesa region and Crimea. The preservation of the moisture content of the atmosphere at the background of a deficit of atmospheric precipitation was revealed. It indicates the preservation of the potential of precipitation for Ukraine, especially due to the southern cyclones. The conducted analysis of the variability of regional atmospheric indices demonstrated the presence of the certain significant trends; a stable trend component, in particular the strengthening of the North Atlantic Oscillation and its Eastern counterpart (the Mediterranean and Eastern European Oscillation,); as well as asynchronous cross-correlation relationships. The best asynchronous relationships with precipitation anomalies in the summer months are found for indices with a time lag of 3-5 months.