The Influence Of Interdecadal Variation Of Temperature Over The Tibetan Plateau On Aerosols Of Its Surroundings In Winter

The Tibetan Plateau(TP)has a unique geographical location and climatic characteristics,which make the interaction between the TP and aerosols of its surroundings is one of the hottest issues.In recent years,large numbers of observations point out that the warming rate of the TP has exceeded the global in the same period,and the abnormal warming of the TP influences circulation,which may lead to a series of environmental problems.I analyze the interdecadal variation characteristics of temperature over the TP and the influence of temperature over the TP on aerosols of its surroundings from 1980 to 2019 in winter through the use of station observations,satellite remote sensing data,and reanalysis data.The aerosols in eastern China and northern India are associated with the enhanced westerly jet,weakened winter winds,increased atmospheric stability,and reduced precipitation,but the influence mechanisms are slightly different.The main findings are as follows:(1)The warming rate of the TP is about 0.15? decade-1,which located in central and eastern TP,about 0.3? decade-1.The warming rate of the TP shows positive,negative,and positive phases during 1980-1992,1993-2002,and 2003-2017.The decadal variability of temperature over the TP exhibits statistically significant associations with Aerosol Optical Depth(AOD)in eastern East Asia and northern South Asia,the correlation coefficients are 0.33 and 0.35,respectively.(2)Due to the warming of the TP,the atmospheric circulation and the inversion layer make aerosols to accumulate in eastern China.On the one hand,the warming rate of the TP enhances the meridional temperature gradient in northern China and strengthens the oblique pressure of the atmosphere in winter.Through transient eddy mean flow further makes the westerly jets to enhance and move northward,which strengthened westerly winds in northern China and transported natural and anthropogenic aerosols from northern China to eastern China.On the other hand,the westerly jet transports the abnormal temperature over the TP downstream to affect eastern China,forming an inversion layer in eastern China,suppressing the vertical convection and forming a secondary circulation in eastern China,weakening the diffusion of aerosols in eastern China,the AOD increased by 0.16.(3)Due to the warming of the TP,the decreasing westerly winds and the subsidence temperature inversion make aerosols to accumulate in northern India.On the one hand,the warming of the TP weakened the meridional temperature gradient and decreased the oblique pressure of the atmosphere,which formed abnormal anticyclonic circulation.Abnormal high pressure existed in northern India,which inhibited the diffusion of aerosols in northern India.On the other hand,the high-altitude meridional circulation is dominated by southerly winds and blocked by the TP,forming a sinking airflow in northern India,leading to subsidence temperature inversion,inhibiting the diffusion of aerosols,the AOD increased by 0.5.