The Characteristics Of The Winter Stratospheric Explosive Warming In The Northern Hemisphere And The Cold Wave In My Country And Their Possible Connections

This study uses the latest Chinese station temperature observation data and global atmospheric reanalysis data to study the climatological characteristics of the frequency and intensity of cold waves and other cold air in the past 60 years the characteristics,causes and effects of different types of stratospheric explosive warming.Atmospheric feedback,and from the perspective of isentropic potential vortices,the relationship between the explosive warming of the stratosphere in winter in the northern hemisphere and the cold wave in February 2010 was analyzed,and the possible causes and mechanisms of the cold wave were explored.The main conclusions obtained are as follows:(1)There are obvious monthly and seasonal differences in the frequency and intensity of cold air processes such as cold waves in China.Regional cold waves occur most frequently in autumn,and national cold waves,regional cold air and national cold air occur most frequently in winter;The average intensity of the regional cold air process(the sum of the cold wave and the cold air process)is the largest in February,and the average intensity of the national cold air process is the largest in November.During the cold period(1960-1986),the frequency of national cold waves in winter decreased significantly(-0.57 times/10 years),and the frequency of regional cold air and all types(the sum of national and regional)cold air processes increased significantly(respectively 1.37 times per 10 years,1.28 times per 10 years);during the warm period(1987-2019),the frequency of national cold waves decreased significantly in January(-0.17 times per 10 years),while the frequency of regional cold air increased significantly(0.53times)/10 years).(2)A total of 31 strong explosive warming events(SSW)occurred from 1979 to 2019,4times for the Eurasian-North American type(ENA),6 times for the Atlantic-East Asia(AEA)type,and 6 times for the Aleutian invasion type(AI).Second,the North American Invasive(NAI)11 times;before ENA-type SSW,the blocking situation in the Atlantic and Aleutian regions caused the polar vortex to split into two low-pressure centers located in the Eurasian and North American continents;before the occurrence of AEA-type SSW,the Ural The combined action of the mountains and the high-pressure system in the North American continental region makes the two low-pressure centers where the polar vortex splits are located in the Atlantic Ocean and East Asia,respectively.Before the occurrence of AI-type SSW,the polar vortex in the stratosphere was pushed by the Aleutian high pressure invading the polar region;before the occurrence of the NAI-type SSW,the polar vortex in the stratosphere was pushed by the high pressure in the western North American continent that invaded the polar region.Whether the stratospheric circulation anomaly signal after SSW can propagate downward depends on the intensity,location and duration of the polar vortex disturbance.The geopotential height anomaly of some SSW events can propagate down to the troposphere,causing the height field and temperature field in the corresponding area of the troposphere.It takes about 10 to 15 days to spread from 10 hPa to 500 hPa.(3)Before the outbreak of the cold wave in February 2010,an AEA-type SSW event occurred.The center of the high isentropic potential vortex originating from the splitting of the polar vortex moved to the northern part of East Asia,accompanied by the eastward and southward movement,and was characterized by high IPV values.The cold air column is stretched in the vertical direction,and the increased cyclonic vorticity of the air column will lead to the development of the cold vortex system in the corresponding area in the troposphere.The north wind on the west side of the cold vortex can transport strong cold air south and down along the isentropic plane is conducive to the accumulation of strong cold air in Mongolia and Siberia.As the high-potential vortex cold air column continues to move east and south to East Asia,the East Asian trough rapidly deepens,and the northeast airflow behind the trough guides the cold air southward,and a cold wave erupts.Further analysis shows that during the propagation of the high-potential vortex cold air column to the south,east,and downwards,the airflow near the center of the high-potential vortex on the isentropic surface moves downward along the isentropic surface on its east and south sides,causing the lower layers of the corresponding area.The strong increase of Siberian high pressure caused the outbreak of a cold wave in our country.