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Abstract: In this study,using data from 840 observed stations and ERA5 reanalysis,the decadal variation characteristics of the nationwide cold wave frequency in the cold season over the past 63 years (1960—2022) were analyzed.The statistical results show the following:against the background of global warming,the decreasing trend of cold wave frequency reversed in 2012,then showed a significant increasing trend from 2012 to 2022.During the latter period,the Ural Mountain blocking frequency was significantly negatively correlated with the occurrence frequency of nationwide cold waves.The Ural Mountain blocking high inhibits the occurrence and development of high-altitude jet streams,weakens the zonal circulation of the atmosphere,and blocks the southward movement of cold air masses in the Arctic,in turn reducing the frequency of cold waves.At the same time,the Ural Mountain blocking high favors weakening the surface 2 m temperature gradient over mid-to-high-latitude Eurasia.The frequent occurrence of Ural Mountain blocking often leads to more weather-scale phenomena of Arctic warming and mid-latitude cooling.In addition,Arctic warming effect itself also has a significant negative correlation with China’s cold wave frequency.Arctic warming reduces the temperature difference between mid-to-high latitudes,and weakens the westerly belt,thus also weakening the transport of cold air.Over the past 11 years,the Ural Mountain blocking frequency has shown a significant decreasing trend.Correspondingly,the zonal gradient of potential vorticity on isentropic surfaces has a linear increasing trend,which is unfavorable for the maintenance of blocking highs.Along with this,the Arctic warming effect also shows a weakening trend.This atmospheric circulation configuration is conducive to China's increase of cold wave frequency in recent years.
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