Abstract

It is revealed that there was a significant increase in the Bowen ratio in the Volga, Southern, and North Caucasian federal districts in the second half of the 20th century–beginning of the 21st century. This indicates a strengthening of sensible heat flux and a reduction of latent heat flux in the heat and moisture balance. These changes are caused by a significant temperature rise, especially in the south of European Russia, with a regional decrease in precipitation. The Bowen ratio is inversely proportional to precipitation and NDVI and directly proportional to temperature. In the steppe zone represented by the Volga, Southern, and North Caucasian federal districts the long periods of predominance of the Bowen ratio anomalies of a certain sign can be distinguished for June and July: the positive ones in the 1950s and until the mid-1960s, the negative ones after that until the early 2000s, and the positive ones since the middle of the first decade of the 21st century. Since the second decade of the 21st century, the positive anomalies of the Bowen ratio have become more frequent in some years and have exceeded the standard deviation. An increase in the contribution of heat to the heat and moisture exchange balance led to a degradation of vegetation conditions in the Volga, Southern, and North Caucasus federal districts. In the south of the Siberian Federal District, the fluctuation of the Bowen ratio anomalies is less pronounced than in European Russia, which suggests some stability of heat and moisture supply in summer over the past 70 years.

中文翻译：

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气候变化条件下俄罗斯南部农区夏季热湿比

摘要

据透露，20世纪下半叶至21世纪初，伏尔加联邦区、南高加索联邦区和北高加索联邦区的鲍文比率显着增加。这表明热湿平衡中显热通量的增强和潜热通量的减少。这些变化是由气温显着上升引起的，特别是在俄罗斯欧洲部分南部，以及区域降水量减少。Bowen 比与降水量和 NDVI 成反比，与温度成正比。在以伏尔加河、南高加索和北高加索联邦区为代表的草原地带，6月和7月可以区分出某种符号的鲍文比异常长期占主导地位：20世纪50年代至1960年代中期为正值，此后直到2000年代初期的负面影响，以及21世纪第一个十年中期以来的正面影响。进入21世纪第二个十年以来，鲍文比率的正异常在某些年份变得更加频繁，并且已经超过了标准差。热量对热量和水分交换平衡的贡献增加导致伏尔加河、南高加索和北高加索联邦区的植被条件退化。在西伯利亚联邦区南部，鲍文比异常的波动不如俄罗斯欧洲部分那么明显，这表明过去70年夏季热量和水分供应具有一定的稳定性。