| The thermal effect of the Tibetan Plateau has important effects on the global atmospheric circulation and China weather and climate, and the sensible heat flux plays a vital role in the Tibetan Plateau atmospheric heat source and sink and the surface heat balance. However, due to the complex topography and ground condition of the Tibetan Plateau, the difference of climatic conditions and the lack of representativeness of the observation stations on the Tibetan Plateau, the calculation of surface sensible heat flux has been uncertain. Then this paper established sensible heat flux parameterization scheme of the Tibetan Plateau, using the observation data and reanalysis data,combined with a variety of satellite remote sensing data, a sequence of sensible heat flux during 2000?2014 years was established, studied the temporal and spatial variation characteristics in recent 15 years in the thermal analysis, and the relationship between snow and wind and differential temperature factors. Results show:(1) The optimization scheme of roughness is obtained, by modifying the original profile formula with increasing the vegetation index and vegetation height. The optimization scheme of additional damping of heat transfer (kB-1)is obtained, by using of temperature difference between the surface and atmosphere. Finally, a set of sensible heat flux parameters for the heterogeneous land surface of the Tibetan Plateau is obtained. The heat transfer coefficient of observation data is used to test the results of this paper.The spatial distribution and time trend of sensible heat flux are analyzed,compared with four sets of reanalysis data consists of ERA-Interim, JRA-25,NCEPR1 and NCEPR2. The results of this paper has the same area of the maximum values as other results. All kinds of data show the trend of increasing in the sensible heat during 2000?2014, but the sensible heat flux value of this paper is closest to the observation data.(2) Based on the analysis of the spatial distribution characteristics in the Tibetan Plateau, it is found that the spatial distribution of aerodynamic roughness(Z0m), kB-1 and thermal roughness(z0h) are closely related to vegetation index, and the parameters are very different in different regions of the plateau. For different eco geographical regions, the interannual variation of heat transfer coefficient (CH) is different, and the high vegetation height,density and thermal characteristics of the surface correspond to high zoh and CH. The sensible heat flux in the Tibetan Plateau is higher in the south than in the north, it is higher in the east than in the west, and it in summer maximum and winter minimum. It is higher in regions with high vegetation and large differences between ground and air temperature. The sensible heat flux has the interannual variation trend of generally increasing after 2000, different regions varing with different rate. The sensible heat flux of western hinterland has small weakening trend, but southeast has the largest annual increase rate as the regional of largest average sensible heat flux.(3) There is a significant negative correlation between sensible heat flux and snow cover in the Tibetan Plateau, and the influence of spring snow on summer heat is stronger than that in spring. There are great differences in different seasons and regions of the relationship between the sensible heat flux and the wind speed in the Tibetan Plateau, and the relationship in most of regions is larger than that in summer and winter, and most of regions were positively correlated in spring, but negatively correlated in summer and winter.There is a significant correlation between the sensible heat flux and temperature difference between the surface and atmosphere in the Tibetan Plateau. In addition to the two eastern regions was negatively correlated in summer, and hasn't passed the reliability test in autumn, the other regions are positively correlated well in all seasons, which is consistent with the sensible heat flux formula. The results may be affected by changes in vegetation growth. |
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