A Remotely Sensed Retrieval Study On Land Surface Temperature In Alpine And Plateau Region

LST(Land Surface Temperature) is a good indicator of the energy balance at the Earth's surface and the greenhouse effect. It is one of the key parameters in the physics of land-surface processes on a regional as well as global scale. It combines the results of surface-atmosphere interactions and energy fluxes between the atmosphere and the ground. Therefore it is required for a wide variety of climate, hydrologic, ecological and biogeochemical studies. Estimating LST information in alpine and plateau regions by the way of Remote Sensing, and exploring its spatial distribution are significant to the protection of mountain ecosystem and regional sustainable development in middle and downstream area.On the basis of systemic summary of domestic and foreign LST algorithms, 7 kinds of split-window algorithms are compared and discussed. Finally, Becker-Li (1990) algorithm is chosen to retrieval LST from MODIS data in Qilian Mt.The conclusions are got as following:1 LST obtained from satellite have the advantage with which the traditional method cannot be compared. It can reflect the average condition and the spatial distribution of underlying surface temperature in each pixel. Although the LST error from Remote Sensing data is avoidless, at present it is the most efficient and convenient method of getting the LST in large area.2 The distribution of instantaneous LST is in general accord with macroscopical variation of synchronous air temperature data. Low temperature is corresponding with the surface of glacier and snow cover first, and then the surface of water;higher temperature occurs at the surface of wind-sand landform, such as bare soil and desert, which is consistent with LST distribution law. There is a distinctive difference in LST between the valley, plain, and upper part of mountains. Topography makes a complex impact on the spatial distribution of LST, which varies with latitudes, seasons, climates and underlying surfaces.3 Diverse topography and different surface covers of underlying surface decide the spatial distribution patterns of LST. Multiple stepwise regression analysis shows thataltitude, instantaneous incident solar radiant energy, surface albedo, NDVI, slope and latitude influence the spatial distribution of LST deeply, which could explain the law of LST distribution pattern at 78%.4 The vertical regulation of LST is discussed. The results show that at the time of the Terra-MODIS overpass, the LST lapse rate varies from 5.42~6.56°C/Km. The minimum value happens at the direction of sunshine, which are approximate 45.42°C/Km on the right south side of mountains;the maximal values happens at the opposite side of sunshine, which are 6.56°C/Km at the north side of mountains. The LST lapse rate on the right east and right west are 5.73"C/Km and 5.84°C/Km respectively. LST lapse rate in high altitude regions is higher than low altitude regions.