The Interannual and Decadal Variation Characteristics of the Sensible Heating at Different Elevations over the Tibetan Plateau and Attribution Analysis

Based on the daily regular meteorological observations in the period of 1961—2014 provided by the China Meteorological Administration, the climatological characteristics of the sensible heating (SH) over the Tibetan Plateau (TP) in different seasons and at different elevations have been studied. The impacts of the drag coefficient for heat and air density on SH have also been analyzed. Besides, the temporal and spatial distributions of SH over the TP on different time scales are investigated. Furthermore, the contributions of surface wind speed and ground-air temperature difference to the variation of SH on interannual and decadal time scales are revealed. The results show that the SH calculated by using real air density and constant drag coefficient for heat is most reasonable. The SH increases with increasing elevation of the TP, and the maximum SH scores in spring with the minimum occurs in autumn and winter. The spatial distribution of SH over the TP is that, the southeast (south) part is large (small) while the north part is small (large) in spring (summer). The first leading mode of empirical orthogonal function analyses (EOF) for spring and summer SH over the TP show an out of phase distribution between south part and north part on interannual time scale, and between the main body and northeast part on the decadal time scale. Furthermore, SH increases from 1961 to the late (early) 1970s in spring (summer), and then decreases until early 2000s, after that it increases. Besides, the trends of spring and summer SH show uniform decreasing in the whole TP with particularly pronounced in the south part during 1979—2003. The surface wind speed and ground-air temperature difference contribute nearly equally to the variation of SH on the interannual time scale, however the former is larger than the latter on the decadal time scale.