Correlation Analysis Between Rossby Wave Energy Propagation And EASJ's Different Evolutionary Modes

The different modal evolution characteristics of the East Asian Subtropical Westerly Jet(hereinafter abbreviated as EASJ)have important implications for the weather and climate change characteristics in East Asia.In addition,the wave energy propagation characteristics of the rossby wave on the westerlies are closely related to the evolution characteristics of the different modes of the westerly jet.In order to study the evolution characteristics of different modes of EASJ and the wave energy propagation characteristics of rossby waves,this paper studies the evolution characteristics of different modes of EASJ in different seasons,and conducts in-depth analysis on the rossby wave energy propagation characteristics in the westerly jet stream,finally,according to the characteristics of the intensity and North-South migration of EASJ,the corresponding rossby wave energy propagation characteristics are obtained.The main findings are as follows:(1)The first mode of spring zonal wind characterizes the EASJ intensity change feature,and the second mode characterizes the EASJ north and south position shift feature.The first zonal wind modes in summer,autumn,and winter all characterize the EASJ north-south position shift feature,and the second modes all characterize the EASJ intensity change feature.(2)During winter,there is a stable high-speed wave guide zone along the westerly jet.In spring,the wave guide weakens and moves westward.In summer and autumn,the wave number on the north side of the jet stream flow decreases rapidly,and the wave activity on the jet stream and on the south side of the jet flow is strong.In spring,the positive vorticity source area of 200hPa is mainly concentrated in Lake Baikal and China's Tibet area,and the negative vorticity source area is mainly concentrated in the south of China.The intensity of vorticity source weakens with the passage of time.in summer,the large value area of vorticity source is mainly located in the area north of 40~0N;the zonal distribution of vorticity sources in autumn and winter is obvious.(3)In spring,the rossby wave energy propagates eastward along the westerly jet.In summer,the flux divergence of rossby wave is distributed in block form,and the intensity of wave flux is roughly along the south and north sides of the summer jet axis.The convergence band of the rossby wave flux in the autumn coincided with the position of its jet axis,and the flux and divergence of the Rossby wave in winter are the strongest in the whole year.(4)In spring,when the intensity of EASJ is abnormally strong(weak):the positive vorticity source intensity in Xinjiang of China and the Pacific is weak(strong),and the divergence intensity of wave flux in Northwest China and Japan is strong(weak).In summer,when the position of EASJ is abnormally north(south),the intensity of positive vorticity source of rossby wave in Inner Mongolia is weak(strong),and the convergence intensity of wave flux in southern Mongolia and northeastern India are weak(strong).In autumn,when the EASJ position is abnormally north(south),the positive vorticity intensity in the central of Inner Mongolia and Western Pacific is weak(strong),and the divergence intensity of the wave flux is weak(strong)in the southern part of China and the northern part of Japan.In winter,when the EASJ position is abnormally north(south),The divergence winds are weak(strong)in Qinghai,Heilongjiang northeast,and Taiwan to the south of Japan.