Features of the dynamics of heat waves in selected cities of Ukraine

Abstract

Formulation of the problem. One of the main manifestations of regional climate changes in Ukraine on the background of global warming is substantial rise of air temperature and increasing of extreme weather conditions. Therefore heat waves became a concern. Detection of heat waves and their physical and statistical characteristics on the territory of Ukraine was done by many researchers only during warm period of the year and on the basis of fact data. But it's interesting to find out what happens in this context during cold period as well because heat waves affect not only human health but also agriculture, transportation etc throughout the year. Besides in order to overcome negative consequences and for adaptation of people for climate changes prognostic values of meteorological indices, in particular air temperature according to modern climate change scenarios.

Review of previous publications. Consequences of thermal waves impact on population health is being studied in different countries of the world and in the main medical data base PubMed there are more than 1000 publications in this branch of research. But still there is no universal definition of heat waves which could be used as criteria for detecting this anomaly in all the researches. This can be explained that depending on challenges of scientific research or practical service of household activity waves of certain intensity or duration can be the most interesting. 

Purpose. The aim of this work is detection of heat waves on the basis of actual and scenario data and analysis of their physical and statistical characteristics and dynamics until 2050.

Methods. Heat waves were detected on the base of actual data and model ranges by low (RCP 2.6), medium (RCP 4.5), high (RCP 8.5) levels of greenhouse gases emissions and also there were analyzed their physical and statistical characteristics and dynamics until 2050 in different regions of Ukraine.

Results. The smallest annual number of heat waves is recorded in the south of Ukraine and the maximum heat wave duration is approximately the same at all the research stations (Uzhgorod, Kharkiv, Odessa). According to all climate change trends that were used, the greatest number of heat waves in the next thirty years is expected in the south of Ukraine, with a maximum in the cold season (October-April). The intensity of heat waves, expressed by the cumulative temperature, during the cold period slightly exceeds this index during the warm period in the west and north-east and substantially exceeds it in the south, and heat waves of the same duration can have quite different intensities.

Conclusions. In the west of Ukraine, there is a trend of increasing the number of heat waves and their duration over the studied period by decades, in the northeast and south - these indicators have fluctuated. It was discovered that in all regions, according to actual data, heat waves of 6-9 days have the highest recurrence (82% of total amount of heat waves per year); according to the RCP2.6 scenario, their recurrence will be minimized (up to 52%) in the south of the country. According to all used climate change trends by 2050, the highest number of heat waves is expected in southern Ukraine, with a maximum during the cold season (October-April). The intensity of heat waves of the cold period is higher than during the warm period in all regions of Ukraine, especially the south.