Current state and tendencies of distribution of ground frosts within the territory of Ukraine

Abstract

The purpose of this work consists in identifying the main trends of present-day formation and distribution of ground frosts throughout Ukraine. For this purpose the analysis of a minimum air temperature field has been conducted based on observation data at 186 stations of Ukraine for the period from 1991 to 2014. It is known that extreme values of air temperature are much more informative than its average values. Therefore analyses of meteorological extreme values usually lead to more substantial and qualitative results. In the course of the work, occurrences of frost in April, May and September have been studied separately from each other while these three months are deemed to be the most dangerous in terms of frosts' frequency and negative impact. In order to identify trends to occurrence of this dangerous weather phenomenon a comparison of two decades of 1991-2000 and 2001-2010 has been made. In addition, the latest observation period of 2011-2014 has been considered separately taking into account the results of comparative analysis of two preceding decades. The results of the work indicate a decrease of number of September days having this dangerous weather phenomenon during the last few years. However, recurrence of frosts remains stably high in April while in May it appears to be high only in certain years. The obtained results also indicate the fact that the northern and northeastern territories of Ukraine appear to be the most vulnerable to frosts. Thus it should be noted that a threat of adverse consequences caused by ground frosts is still there and remains to be quite high, especially for agriculture.

Keywords

• global climate changes, ground frosts, weather characteristics, minimum temperature, temperature gradations, recurrence