Abstract
Observational and reanalysis data show that the surface air temperature (SAT) over most parts of Europe in June of 2019 broke the highest temperature on record. In this study, we investigate the factors for the formation of this record-breaking high temperature over Europe, focusing on the role of atmospheric circulation anomalies. A strong anomalous anticyclone appeared over Europe, with a quasi-barotropic vertical structure. On one hand, the downward motion anomalies associated with this anomalous anticyclone led to less cloud cover and an increase in downward shortwave radiation, which contributed to the SAT warming over Europe. On the other hand, southerly wind anomalies to the west side of the anomalous anticyclone also resulted in SAT warming via carrying warmer and wetter air northward from lower latitudes. The formation of the anticyclonic anomaly over Europe in June of 2019 was closely related to an atmospheric wave train propagating eastward from the mid-high latitudes of the North Atlantic to Eurasia. The atmospheric wave train over the North Atlantic–Eurasia region is suggested to be mainly related to the Atlantic–Eurasia teleconnection pattern. Further analysis indicates that a decrease in the local soil moisture over Europe may also have escalated the surface temperature warming through a positive land–atmosphere feedback.
Highlights
High temperatures during warm seasons could lead to remarkable impacts on human mortality, socioeconomic development and ecosystems [1,2,3,4]
It was shown that positive surface air temperature (SAT) anomalies of higher than 2 ◦ C over Europe were maintained from June 1st to 27th
As demonstrated by previous studies, atmospheric circulation with the high temperature can enhance the deficiency of soil moisture which in turn leads to the anomalies in association with the high temperature can enhance the deficiency of soil moisture which escalation of surface air temperature warming through the positive land–atmosphere feedback [11,21]
Summary
High temperatures during warm seasons could lead to remarkable impacts on human mortality, socioeconomic development and ecosystems [1,2,3,4]. In regard to the factors for the heat extremes occurring in Europe, previous studies have highlighted the important role of large-scale atmospheric circulation anomalies [6,7,8,9]. Consecutive high temperature events over Europe are generally associated with the intense and persistent anticyclonic circulation anomaly which is in favor of generating local subsidence and prolonged hot conditions at the surface [10,11,12,13,14,15]. Studies have analyzed the impact of the anomalous anticyclone associated with quasi-stationary Rossby waves over the mid-high latitudes of Eurasia in contributing to the occurrence of heatwave events [6,7,8,16,17,18,19,20].
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