Abstract

The distribution pattern of the characteristics of spring–summer droughts during periods of increased and decreased annual wetting in 12 administrative entities of the south of European Russia in 1901–2018 are studied. During this time, four periods of different humidification conditions (alternating wetter, dry, wet and again dry periods) of different durations are well traced according to anomalies in the aridity index in seven regions: Kursk, Belgorod, Voronezh, Saratov, Volgograd, and Rostov oblasts and the Republic of Kalmykia. A desiccation period was noted in Samara and Astrakhan oblasts from the beginning to the middle of the 20th century. The desiccation period then gave way to a wetter one. The most frequent change of periods with different moisture conditions was observed in Stavropol krai, where five alternating periods were identified. It has been established that the frequency of spring–summer droughts is consistent with the long-term humidification conditions. According to the standardized precipitation index, it increases on average by 1.5 times in the dry period with a slight increase in drought intensity. The conditions of increased humidification observed in all of the examined administrative subjects in the second half of the 20th century were replaced by drier conditions at the beginning of the 21st century. The spread of more arid conditions began in the eastern oblasts. The development of the dry period in the 21st century is confirmed by the distribution of the NDVI vegetation index in the negative trend. In the absence of statistically significant aridization trends for more than a century, all of the considered oblasts of the south of European Russia undergo long, intracentury periods of aridization strengthening and weakening, which are characterized by significant differences in the frequency and intensity of spring–summer droughts.

中文翻译：

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欧洲俄罗斯南部干湿时期春夏季干旱的特征

摘要

研究了1901年至2018年俄罗斯南部欧洲12个行政实体年湿润增加和减少期间春夏季干旱特征的分布模式。在这段时间内，根据七个地区的干旱指数异常，可以很好地追踪到四个持续时间不同的加湿条件时期（交替的潮湿，干燥，潮湿和再次干燥时期）：库尔斯克，别尔哥罗德，沃罗涅日，萨拉托夫，伏尔加格勒和罗斯托夫州和卡尔梅克共和国。从20世纪初到20世纪中叶，萨马拉和阿斯特拉罕州注意到了一个干燥时期。然后，干燥时期被湿润的地方所取代。在斯塔夫罗波尔（Stavropol krai），观察到了不同水分条件下周期最频繁的变化，其中确定了五个交替的周期。已经确定，春夏季干旱的频率与长期加湿条件一致。根据标准化的降水指数，在干旱时期平均增加1.5倍，干旱强度略有增加。在20世纪下半叶，在所有检查过的行政科目中观察到的增湿条件都被21世纪初的较干燥条件所取代。东部州开始出现更多干旱状况。NDVI植被指数呈负趋势分布，证实了21世纪干旱时期的发展。在一个多世纪没有统计上显着的干旱化趋势的情况下，所有被认为是欧洲南部欧洲的州都经历了很长时间，