The Characteristics Of Atmospheric Diabatic Heating And Its Relationships With Precipitation And Circulation Over Tibetan Plateau

Tibetan Plateau (TP) the giant elevated landscape plays key role in modulating Asia summer monsoon via dynamic, thermodynamic and mechanic lifting mechanisms. The spatial and temporal distribution of atmospheric diabatic heating (DH) is key important to understand the coupling of energy and moisture between land surface and atmosphere over TP. In this study, the residual diagnosis of DH from ERA40 and NCEP reanalysis, the precipitations and latent heating products from TRMM PR are investigated to reveal the uncertainties in DH. Discrepancies of DH between ERA40 and NCEP are found in the southern slope of TP in summer. The DH from ERA40 is much stronger than NCEP in high altitudes in southern slope of TP. The area with strong ERA40 atmospheric heating extent from low altitudes to high altitude exceeding 4000 meters. However, in diagnosis of NCEP, strong atmospheric heating only located at lower altitudes less than 4000 meters. Such differences are evident in both ground layer and 400-500hPa layer indicating significant contribution from latent heating (LH). As an indicator of LH, the precipitation in southern TP estimated from ERA40 is much heavier than those from NCEP diagnosis and TRMM PR observations. The overestimation of precipitation by ERA40 matches the DH distribution very well. Based on the vertical cross-section of DH and atmospheric circulation along 92.5°E, strong positive DH over the high altitudes of southern TP extend to high troposphere (?300hPa) vertically as seen from ERA40, while the associated NCEP DH only located at lower troposphere. The diagnosis of vertical velocity and horizontal divergence at the 200hPa layer from ERA40 are also stronger that those from NCEP. It was concluded the uncertainties of precipitation and associated LH in south slope of TP are the main error sources of understanding the mechanisms of TP-Atmosphere interaction.