Comparative analysis of frequency of dry winds occurrence in Ukraine in the mid-20th century and at the beginning of the 21st century

Dry winds in Ukraine present a dangerous phenomenon which can significantly impact on crop yields. The winds damage agricultural crops active development of which occurs in spring and summer time. Their impact can in a short time reduce or destroy further yield. Study of spatial and temporal distribution of the dry winds, their meteorological characteristics, dynamics of their development and circulation processes resulting in their formation in Ukraine is a very urgent problem because almost every year the dry winds and droughts occur at the time of vegetation period. The current research of spatial and temporal distribution of the dry winds and its meteorological characteristics on the territory of Ukraine under the conditions of changed climate is an urgent problem because this phenomenon occurs over almost every vegetation period. The paper describes the results of comparative analysis of average number of days witnessing the dry winds at 14 meteorological stations in Ukraine located in different agro-climatic zones for the periods of 1936-1964 and 1995-2015. The number of dry winds significantly increased at most of such stations located in different parts of Ukraine. Same as over previous periods, the greatest repetition of days with the dry winds occurred in the south and the south-east of the country where, according to the data from some meteostations, vegetation period may, on average, consist of up to 27 days when dry winds blow. The reason for such increase is explained, firstly, by change of the large-scale atmospheric circulation resulting in weakening of the heat and moisture inter-latitude exchange which in its turn causes change of the temperature and humidity regime in Ukraine and, secondly, by increase of frequency of synoptic processes accompanied by formation of arid phenomena on the territory of the country. These changes could be traced when observing the positive anomalies of average air temperature during recent decades. The negative anomalies of precipitation and change in their distribution contribute to the formation of conditions that increase frequency and intensity of droughts. The obtained results indicate that changes of the regional climate contributed to the increase of frequency and prevalence of the dry winds in Ukraine.