Abstract

Based on the Standardized Precipitation Index (SPI) data for June–August in 1950–2016, the frequency of severe atmospheric droughts in the south of the East European Plain is analyzed. It is found that droughts were observed more often in the periods of warmer SST in the North Atlantic as compared to its colder period. It was revealed that the frequency of droughts in the Volga region and in the north-west of Kazakhstan was the greatest (to 19 droughts/100 years) in the years when the SST of the North Atlantic was extremely warm. The least frequency of severe droughts (4 droughts/100 years) in the considered regions was observed in the years of the extremely cold North Atlantic. Favorable conditions for the development of severe summer droughts in the south of the East European Plain in the period of the warm North Atlantic were registered when regional zonal circulation in the Atlantic-European sector weakened and the frequency of days with atmospheric blocking in the east of the East European Plain increased. Such conditions were related mainly to the increasing frequency of negative phases of the North-Atlantic Oscillation and the East Atlantic/Western Russia (EA/WR) pattern. The greatest (three-fold) increase in the blocking frequency was registered during the negative phase of the EA/WR pattern as compared to its positive phase.

中文翻译：

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北大西洋海温变化和大气环流变化对东欧平原夏季干旱发生频率的影响

摘要

根据1950-2016年6月至8月的标准化降水指数（SPI）数据，分析了东欧平原南部严重的大气干旱发生频率。结果发现，与较冷的时期相比，北大西洋的海温升高时期更常观察到干旱。据透露，伏尔加河地区和哈萨克斯坦西北部的干旱频率在北大西洋海温异常温暖的年份最大（达19次干旱/ 100年）。在极冷的北大西洋年份中，在所考虑的区域中，发生严重干旱的频率最低（4干旱/ 100年）。在北大西洋温暖的时期，东欧平原南部发生严重的夏季干旱，这是有利的条件，当时大西洋-欧洲部分的区域性地带环流减弱，而东部的大气层被阻塞的天数出现东欧平原增加。这种情况主要与北大西洋涛动和东大西洋/俄罗斯西部（EA / WR）模式的负相频率增加有关。与EA / WR模式的正相位相比，在EA ​​/ WR模式的负相位期间出现了最大（三倍）的阻塞频率增加。这种情况主要与北大西洋涛动和东大西洋/俄罗斯西部（EA / WR）模式的负相频率增加有关。与EA / WR模式的正相位相比，在EA ​​/ WR模式的负相位期间出现了最大（三倍）的阻塞频率增加。这种情况主要与北大西洋涛动和东大西洋/俄罗斯西部（EA / WR）模式的负相频率增加有关。与EA / WR模式的正相位相比，在EA ​​/ WR模式的负相位期间出现了最大（三倍）的阻塞频率增加。