Warming Amplification Over The Large-scale Topographies And The Correspoding Changes Of Surface Energy Balance

Based on in situ observations provided by the China Meteorological Administration (CMA) during 1979?2014 (including atmospheric temperature Ta,surface temperature Ts, wind speed V0), the temporal trend of the heat source and Ts of the Tibetan Plateau (TP) have been analyzed. On this basis, with two reanalysis datasets, MERRA and JRA55, and with the tool of surface energy budget equation,warming amplification of the TP after 1998 and its relevant physical processes have been quantitatively analyzed.The results show that the enhanced downward longwave radiation under clear-sky condition (LW) and the positive surface albedo feedback (SAF) related to the reduced snow cover are responsible for the pronounced surface warming,especially in spring and winter. Meanwhile, the changes in cloud radiative forcing(CRF), surface sensible and latent heat fluxes (H+LE), and heat storage (Q) had a much weaker cooling effect. These results indicate that LW and SAF have played an important role in TP surface warming amplification during recent decades.By means of abrupt-change test mothods of Ts during 1958-2014, along with the TP,the Rocky Mountains and the Andes Mountains have also been found to have an abrupt Ts increase in 1997/1998. The result of the surface energy budget equation has confirmed that LW plays an important role in Ts amplification over the Large-scale Topographies; The change of CRF contributes to raise Ts to a great extent in the Rocky Mountains especially in boreal spring and summer, and in the Andes Mountain in boreal summer and autumn. The season which Ts increases most in the Rocky Mountains is the summer, and then follows autumn with LW contributing most to its warming. In the Andes Mountains in boreal winter and spring,LW warms the surfaces mostly, but CRF cools the surface to a large degree, H+LE also cools the land surface. So the seasonal variation of the surface warming in the Andes Mountains is relatively small throughout the year. The change of vertically integrated water vapour has shown its close similarity to the increased LW and to Ts increase, which explains the main cause of warming amplification there.