Concurrent Variations Of The Three Major Storm Tracks In The Northern Hemisphere And Their Possible Influences On Temperature

Based on the daily reanalysis data of the National Center for Atmospheric Research and the National Center for environmental prediction(NCEP/NCAR),the sea temperature data of the U.S.Oceanic and Atmospheric Administration(NOAA)and the atmospheric circulation and ocean indexes of the U.S.Climate Prediction Center(CPC)from 1959 to 2018,this paper recognizes the three major storm tracks in the northern hemisphere in winter as a whole by calculating the storm track indexes,empirical orthogonal function decomposition(EOF),and singular value decomposition(SVD).The characteristics of the three storm tracks in different time scales and the characteristics of the temperature anomaly in the northern hemisphere at the same time were analyzed,and the possible mechanism of the influences of the storm track anomaly on the temperature anomaly was discussed by using correlation and regression analysis.The results are summarized as follows.(1)There are three major storm tracks in the northern hemisphere in winter,and there are two modal of concurrent variations among the three major storm tracks.The conditions of the original field,interannual field,and interdecadal field in the first mode are relatively consistent,showing the northern Atlantic storm track is northerly(southerly),the northern Pacific storm track is southerly(northerly),and the continent storm track is strong(weak).The conditions of the original field and the interdecadal field in the second mode are more consistent,showing that the two oceanic storm tracks are consistently strong(weak),and the continent storm track is southerly(northerly).(2)It can be found that there is an obvious relationship between the concurrent variations of storm tracks and the temperature anomaly in the northern hemisphere in winter.When the northern Atlantic storm track moves to northeast and its intensity is stronger,and the northern Pacific storm track moves to south,the frequency of extreme low temperature in the north of Eurasia and most of North America is less,the temperature in these areas is higher,and the frequency of extreme low temperature in the central North Pacific and northeast of North America is more,the temperature in these areas is lower.When the northern Atlantic storm track moves to south,the northern Pacific storm track move to southwest and becomes stronger,and the continent storm track is weaker,the frequency of extreme low temperature from the northern part of Eurasia to the central part of the North Pacific is more,the temperature in these areas is lower,and the frequency of extreme low temperature in most areas of North America is less,the temperature in this area is higher.(3)The possible influence mechanism of storm tracks anomaly on temperature anomaly is discussed: In the first mode,the northern Atlantic storm track moves to northeast and its intensity is stronger,and the northern Pacific storm track drifts to south.At this time,it is the positive phase of the East Atlantic teleconnection pattern and the Pacific/North American telecorrelation pattern,and the negative phase of the West Atlantic teleconnection pattern.These strengthen the East Asian Jet,leading to the East Asian Trough weakening,causing the meridional wind to be weak.The shallow high-pressure system in the northern Eurasian continent causes the temperature in the region is abnormally high,and the warm air can not go to south due to the weakening of meridional wind.At this time,the North American Jet is weaker and drifts to north,so the cold air in the north gathered in the Greenland area and could not go to south.As a result,only the northeast region of the North American continent is colder.In the second mode,the northern Atlantic storm track is southward,the northern Pacific storm track moves to south and becomes stronger,and the continent storm track is weaker.At this time,it is the positive phase of the Pacific/North American teleconnection pattern,the negative phase of the East Atlantic teleconnection pattern and the West Pacific teleconnection pattern.The East Asian Jet is stronger,the East Asian Trough stretches transversely,and the meridional wind changes into the zonal wind.The westerly wind brings the cold air from Novaya Zemlya to the northern part of Eurasia,causing the temperature in this region to be lower.At the same time,the El Ni?o phenomenon is obvious,and the sea temperature on the Pacific coast is extreme high.The North American Jet bring warm and humid air from the ocean to the North American continent,causing the temperature of the North American continent to be higher.