Український гідрометеорологічний журнал (Dec 2022)
The current regime of heat waves and their impact on the yield of cereal crops in Ukraine
Abstract
Heat waves are one of the most dangerous meteorological phenomena, the manifestations of which have become more frequent in all regions of the globe in recent decades. Due to excessively high temperatures persisting for a long time, heat waves cause heat stress in living organisms and plants, and negatively affect various sectors of the national economy. Although the mechanism of heat wave formation is well known, the question of determining and predicting the intensity and duration of these processes in advance, as well as the areas of their propagation, remains open, including due to the lack of unified concept of a heat wave. This study analyzed the spatiotemporal distribution of extremely warm days and heat waves for the period 1996-2021 in 16 regions of Ukraine, where the production of the main agricultural crops (winter wheat, spring barley, corn) is concentrated. The analysis was performed using the surface skin temperature Ts, which contains information about the temperature of both the canopy and ground surface. It was found that during the study period, the number of extremely warm days increased in all regions of the country and in all seasons of the year, with the most significant increase occurring in the last decade in winter and autumn. The warmest year was 2020, when the number of extremely warm days in some regions reached 100-106 per year. The frequency of heat waves at the end of the study period almost doubled compared to the beginning, reaching an average of 8-10 cases per year. The average seasonal frequency of heat waves was 4-5 cases in summer and 2-4 cases in other seasons. The longest heat waves lasting 17-19 days were recorded in all agro-climatic zones in August 2010. In other seasons, the maximum duration of heat waves did not exceed 10-14 days. Statistical assessment of the relationship between the seasonal number of extremely warm days and the grain yield crops showed that an increase in these days in the spring leads to decrease in the yield crops of winter wheat and spring barley; in summer this negative impact is observed for corn.
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