Retrieving Land Surface Temperature Based on the Radioactive Transfer Equation in the Middle Reaches of the Three Gorges Reservoir Area
基于辐射传导方程的三峡库区腹地地表温度的遥感反演

Land surface temperature(LST)was retrieved from Landsat Thematic Mapper(TM) images in the hinterland of the Three Gorges Reservoir based on the radioactive transfer equation. In the radiation transfer equation,estimation of land surface emissivity was carried out by empirical formulas integrating the function of terrain,water,construction,and natural surface into land surface temperature retrieval by taking into account complex topography and diversity in surface cover types in the hinterland of the Three Gorges Reservoir Area.Results show 1)LST exhibits a decreasing tendency with increasing elevation.In general,human disturbance was relatively less in higher altitude and regions with rolling topography.Solar radiation received was converted mostly into latent heat rather than sensible heat flux.LST was lower over these areas;2) Large differences in land surface water and heat exchanges occurred under different patterns of land cover.LST exhibited high spatial variability,with a descending order as following: construction>natural surface>water.At the same altitude,LST highly corresponded to land cover type and their conversions.At 200 m elevation,the LST retrieval of building was the highest,up to 29.87℃,followed by that of the natural surface with 26.53℃,and the lowest was 22.69℃for water cover;3)Magnitudes of changes in LST at different elevations show marked differences due to differing land over types.However,LST decreased with increasing altitude,showing significant vertical variations.LST of natural land cover types was only 16.42℃at the highest elevation.LSTo f buildings was 27.03℃at the highest elevation;4)LST retrieved at sampling points ranged between the minimum and maximum temperature.LST seems to be closely related to air temperature.These values of LST retrieved in both Fengjie and Wanxian were significantly higher than the average temperature of the corresponding site for the same day.In particular,the LST retrieval was 7.46℃higher than the average temperature in Wanxian for the same day.