A Study On The Relationship Between The Thermal Conditions Of The Qinghai-Tibet Plateau And The Activity Of The Plateau Vortex

In this paper,we use Yearbook of the low vortex shear line in the Qinghai Tibet Plateau and the ERA-Interim dataset to study and analyze the spatiotemporal characteristics of the atmospheric heat source,sensible heat flux,and latent heat flux during the summer of 1998-2016 and the spatiotemporal characteristics of the Summertime TPV generation frequency.At the same time,the relationship between these heat sources and the frequency of TPV generation was discussed.The research conclusions were as follow:(1)From 1998 to 2016,the summertime average value of atmospheric heat source was 88.7 W.m^-2,the summertime average value of sensible heat flux was 48 W.m^-2,and the summertime average value of latent heat flux was 56.1 W.m^-2.Atmospheric heat source have quasi-four-year and quasi-seven-year periodic changes,sensible heat flux and latent heat flux have quasi-four-year and quasi-eight-year periodic changes.The climatic tendency rate of atmospheric heat source and latent heat flux is negative,and the climatic tendency rate of sensible heat flux is positive.The interannual changes from June to August are as follows:the climatic tendency rate of the atmospheric heat source in each month is negative,the climatic tendency rate of sensible heat flux in each month is positive,and the climatic trend rate of latent heat flux is negative in each month except that it is positive in August.(2)TPV,DTPV and NDTPV are mainly concentrated in the north of 30°N and east of 90°E,and most mainly in the northeast of Naqu.The influence systems that affect TPV moving out of the plateau are low-groove and shear systems,and TPV is mainly affected by the shear systems.From 1998 to 2016,Tibetan Plateau Vortex(TPV)annually generated an average of 21.53 in summer.Departure Tibetan Plateau Vortex(DTPV)annually generated an average of 5.84 in summer,Non-Departure Tibetan Plateau Vortex(NDTPV)annually generated an average of 15.68 in summer.TPV,DTPV,NDTPV center geopotential height value are mainly between 576-585dagpm.The annual average geopotential height of TPV,DTPV and NDTPV are 580.8dagpm,578.6 dagpm,and 581.6 dagpm.TPV and NDTPV center geopotential height value climate tendency rates are positive,DTPV center geopotential height value climate tendency rates is negative.TPV and NDTPV have quasi-five-year periodic changes,and DTPV has quasi-four-year and quasi-seven-year periodic changes.(3)In the year of high incidence of TPV,the atmospheric heat source in the central and eastern plateau is relatively strong(weak),the sensible heat flux in the southwestern plateau is weak(strong),and the latent heat flux in the western and eastern plateau is weak(strong),which are beneficial to generation of TPV.(4)In the year of high incidence of TPV,the lower layer of the eastern plateau was controlled by cyclonic circulation,the plateau was affected by the southerly airflow of the cyclonic circulation over Iran,and the upper plateau was controlled by anticyclone,which are conducive to the formation of TPV.In the year of low incidence of TPV,the lower middle and eastern layers of the plateau are affected by the anticyclone circulation,and the upper and lower layers of the plateau are mainly controlled by the easterly airflow,which is not conducive to the formation of TPV.(5)In the year of high incidence of TPV,the low layer of the plateau east of 90°E converged and the high layer diverged,which caused a violent upward movement,which was conducive to the formation of TPV.In the year of low incidence of TPV,the low layer of the plateau east of 90°E diverges and the upper layer converges,which causes a strong sinking movement,suppresses the convective activity of the plateau,and is not conducive to the formation of TPV.At the same time,when the plateau is in the positive advection vorticity zone,it is conducive to the formation of TPV.when the plateau is in the negative vorticity advection zone,the generation of TPV is suppressed.