Characteristics of the droughty phenomena of the current climatic period, meteorological conditions and atmospheric circulation background

The paper provides a description of the arid phenomena of the modern climatic period in the world of regional climate change, including an analysis of individual meteorological variables and components of the solar radiation regime, with an assessment of the state of atmospheric circulation and prognostic potential. The frequency of arid phenomena with an increase in the degree of aridity in most of Ukraine is noted, which is influenced by an increase in air temperature and a deficit of precipitation, due to an increase in direct solar radiation and the duration of sunlight. This is consistent with changes in Central and Eastern Europe. The increase in the degree of aridity has been recorded since the early 2000s, with the greatest trend in 2010-2020, when the area of droughts significantly expanded in space and between seasons, extending beyond the growing season. The occurrence of aridity events during the cold period of the year increases the likelihood of large-scale droughts during the growing season and creates unfavorable conditions for the development of agricultural production. This is associated with the growing influence of anticyclogenesis, especially the phenomenon of synoptic blocking, which determines the increased duration of aridity events. Typical anomalies of regional climate indices and their combinations have been found. They can be used for the diagnosis and seasonal forecast of droughts and reflect the special state of atmospheric circulation of the meridional type with the influence of subtropical anticyclones characteristic of the period of global warming. The significant stability of synoptic processes determines the restructuring of the atmosphere long before the phenomenon and can be used to forecast droughts. Comparison with droughts of the previous climatic period (1970s) shows a special distribution of anomalies of climate indices, which emphasizes the difference in the origin of droughts, the uniqueness of the corresponding synoptic conditions of the modern climatic period with greater temporal residence time of synoptic patterns. If droughts in the 1970s were noted at the beginning of the growing season, then since 2010 they register almost every year covering seasons from winter till autumn season. Analysis of the interseasonal evolution of synoptic processes favorable for the emergence and preservation of large-scale drought phenomena showed a typical transformation of the circulation between seasons.