Simulated trends in surface sensible heat flux on the Tibetan Plateau and the possible causes

Abstract Characteristics of spatial distribution and variation of surface sensible heat (SH) flux on the Tibetan Plateau (TP) were studied using the simulation results from the Noah-MP land surface model for the period of 1985-2015. The inter-annual variations and possible causes were also analyzed. It is found that, the western and central TP witnessed much larger 31-yr mean SH fluxes than the eastern TP. Meanwhile, the inter-annual variations of SH fluxes on the central and western TP were larger than that on the eastern TP. All the regions showed a decreasing trend in SH flux from mid-1980s, but an increasing trend since the beginning of the 21st century. However, the eastern TP got the increasing trend later than the western and central TP. On the whole, the increasing trend began from about 2002. The western and central TP had larger values of Ts–Ta (difference between ground and air temperature) than the eastern TP. Overall, the trends of mean Ts–Ta and SH flux were similar to each other. The changes of mean Ts–Ta were the main causes of the decreasing and increasing trends in SH flux on the TP. Meanwhile, the changes of wind speed and heat transfer coefficient CH are not as important as Ts–Ta.