Temporal And Spatial Variation Characteristics Of Air Temperature On The Qinghai-Tibet Plateau From 1980 To 2018 And Its Future Projections

As an amplifier of global temperature,the Tibet Plateau(TP)has increase significant warming after 1998,and its high altitude has further amplified the warming degree.Studying the spatio-temporal changes in the surface temperature and causes of warming over the TP is significance for predicting future global and regional climate changes.This article closely focuses on the frontier issues of temperature changes on the TP.Based on the station observation temperature data OBS,and JRA-55,ERA-Interim,MERRA three reanalysis data and 16 CMIP6 model data,use the mathematical statistics,Taylor plots,MK mutation test,bilinear interpolation,spatial interpolation and other methods.Firstly,the applicability of the three reanalysis data on the TP was evaluated,selectd JRA-55 to analyze the temporal and spatial characteristics of annual and seasonal temperature warming of the TP from 1980 to 2018.Secondly,it comprehensively explores the possible causes of TP warming in horizontal space and vertical altitude.Finally,based on the CMIP6 model data,it further analyzes the characteristics of the TP future temperature changes and causes.The main conclusions of the paper are as follows:(1)The station observation and JRA-55,ERA-Interim,MERRA data all reveal TP has experienced significant warming,the winter warming is significantly larger than annual and summer from 1980 to 2018.Although the three reanalysis data can reproduce the TP warming to a certain extent,the underestimation of its existence cannot be ignored.JRA-55 shows that the annual,summer,and winter trend are 0.36,0.35,and 0.41 ?/10a,respectively.(2)Analysis of JRA-55 temperature revealed that the annual,summer,winter abruptly changed in 1998,1997 and 2000,respectively,then select 1998 as the annual and seasonal unified mutation year.JRA-55 shows there is a"dual-center" warming zone in the whole TP,The maximum warming rate in winter was larger than annual and summer.There was a significant "cooling-heating" change in the central TP during 1980-1997 and 1998-2018.In addition,the areas with the highest warming rates have transitioned from low altitudes to high altitudes.Among them,there was only above 3000m area has experience EDW from 1980 to 2018,and the maximum warming rate occurred in 4800-5000m in winter while the warming rate decrease above 5000 m.(3)Based on the comprehensive analysis of 18 physical parameters related to warming including surface radiation,clouds,and latent heat in winter 1980-1997 and 1998-2018,it is dound that the significant warming occurs in the central western-TP in winter is mostly caused by the decrease in upward short-wave radiation due to the depletion of snow.The surface albedo decreases while snow melts,the reflected solar radiation decreases leads to the solar radiation remaining near the surface increase.which releases more upward long-wave radiation while heating the surface.Conversely,the plateau cools.(4)The 16 CMIP6 models and mean model MM show that the annual average temperature of the TP will have greater warming,especially the temperature increase in the SSP5-8.5 scenario is almost twice that SSP 1-2.6.After evaluation,CESM2 mode is the best.The analysis of the temperature results of the CESM2 model under four scenarios found that compared with historical periods,the TP temperature in 2015-2100 increased significantly in the central Northern-TP and Tangula Mountains.The warming trend of the Eastern-TP is significantly larger than that surrounding areas.Furthermore,a second warming center has gradually formed in the west with the increase of radiative forcing.Overall,as the overall temperature of the plateau rises in the future,the phenomenon of altitude dependence becomes more and more significant,especially in high altitude areas.This means that when global warming intensifies,the maximum warming rate will appear at higher altitudes.This result will accelerate the melting of glacial snow in high-altitude areas and seriously threaten the living environment around the plateau.In addition,CESM2 shows a more consistent pattern with JRA-55 data,that is,the upward short-wave change caused by snow-albedo is an important reason for accelerating plateau warming.