Research On The Surface Energy Balance Of The Qinghai-Tibet Plateau And Its Influence On The Atmospheric Boundary Layer

Using the reanalysis data from the Final Operational Global Analysis(FNL),NCEP/DOE(NCEP2)data provided by the NCEP/NCAR,the precipitation data from GPCP(Global Precipitation Climatology Project),and the observation data of the stations,this article primarily analyses the feasibility of using the reanalysis data instead of the observed data on the Tibetan Plateau(TP);Then Analysis the distribution,the change characteristics and the trends of the atmospheric boundary altitude,the surface sensible heat flux,and the surface latent heat flux on the TP;Using the sliding T test for mutation testing;Correlation analysis and SVD analysis were used to understand the relation between the height of the atmospheric boundary layer and the surface energy transportation.The correlation coefficient test also was used to find out the influencing factors effected the boundary layer height and the surface energy transport;Through the analysis of the circulation situation,preliminarily discuss the mechanism about how the surface energy transport influence the atmospheric boundary layer.The primary conclusions are as follows:(1)In terms of spatial distribution,the atmospheric boundary layer height on the plateau have the characteristics that the quantity of the height in the western TP is larger than the eastern part and the northern is larger than the southern.The distribution of the surface sensible heat flux of the plateau is consistent with that of the atmospheric boundary layer height,and the surface latent heat flux has the opposite distribution characteristics.In summer,the trend about the atmospheric boundary layer height is significantly decreasing;the latent heat flux is significantly increasing;and the sensible heat flux is increasing first and then decreasing,and the linear trend was not significant.The 2009 is the time of abrupt change in the atmospheric boundary layer altitude on the Tibetan Plateau.From the perspective of comprehensive changes,the trend of changes in the various elements on the Tibetan Plateau has changed significantly around 2009.(2)The spatial average linear variation trend of the atmospheric boundary layer height,the surface sensible heat flux and latent heat flux in summer has obvious regional differences.The plateau is divided into eastern and western regions and found that the change characteristics of the atmospheric boundary layer heights and the surface sensible heat flux in the east and west areas have certain consistency,but the surface latent heat flux changes in the eastern and western regions are almost opposite.The abrupt change time about the atmospheric boundary layer height and surface heat flux in the east and west regions were found to be still in 2009;Before and after the abrupt time,the characteristics and trends of the atmospheric boundary layer height and surface heat flux changes are obviously different.(3)The height of the atmospheric boundary layer is generally positively correlated with the surface sensible heat flux and negatively correlated with the surface latent heat flux.The sensible heat flux in the western plateau has an upward trend,or the sensible heat flux in the eastern region decreases,the atmospheric boundary layer height in the southwestern region rises,and the atmospheric boundary layer height in the eastern and northern regions will decrease.If the sensible heat flux in the western region decreases or the sensible heat flux in the eastern region increases,the boundary layer height in the eastern region will rise and that in the western region will decrease.And when the latent heat flux in the western plateau decreases,or the latent heat flux increases in the eastern and northern regions,the height of the atmospheric boundary layer in the western region rises,and the atmospheric boundary layer height in the eastern and northern regions of the plateau decreases.On the contrary,the latent heat flux increases in the eastern region or the latent heat flux in the western region decreases,the height of the boundary layer in the western region rises and the height of the eastern boundary layer decreases.(4)The plateau near the surface is controlled by Heat Low pressure in the summer,and high altitude is controlled by the South Asia High in the upper atmosphere.This kind of general atmospheric circulation provides the dynamic conditions for the development of the atmospheric boundary layer,it's good for the ascent.The air flow in the ascending motion can transfer the condensation latent heat released by the water vapor phase to the upper troposphere,which is beneficial to the positive feedback of latent heat flux and South Asian High.(5)The important factors that affect the height of the atmospheric boundary layer and the surface heat flux in the western region are 0-10 cm soil moisture content and10 m wind speed;the cloud cover is the influencing factor of the atmospheric boundary layer height and surface latent heat flux in the eastern region.However,the influence degree of each influence factor before and after climate change on the atmospheric boundary layer height and surface heat flux of the eastern and western parts of the plateau will change,for example,the 10 m wind speed becomes an influencing factor of surface latent heat flux in the eastern region after the abrupt climate change.