Study On Simulating The Land Surface Evapotranspiration In Wuding River Basin Based On Remote Sensing Data

The evapotranspiration (ET) occurs in the Soil-Plant-Atmosphere Continuum (SPAC), and it is very importance for vegetation growing. Also, it is a major link in the hydrological cycle with a very important status.The ET on the local scale has been studied for long time, and some mature theories have been formed. The technology of calculating the ET was really feasible. With the society developing and modern agriculture pushing on, the research of ET on the local scale can not be satisfied with the needs at present, and the ET on the regional scale needs to be calculated. With the aid of GIS, RS and observations from agricultural weather stations, the ET of Wuding River Basin on sunshine days from 2001 to 2003 were simulated. The main works in this research were included:(1)Treatment of dataAccording to the need of model, the meteorological information, remote sensing data and GIS database from 2001 to 2003 in Wuding River Basin were collected. Through the check and selection, the data that the quality satisfied the requirements were obtained. Then the meteorological information was interpolated to each hour using the spline interpolation to match up the remote sensing data. With the GIS database, the basic elements of the meteorological were interpolated to each grid by using the IDS (Interpolation Distance Square).The MOD11,MOD13 and MOD43 were ordered and loaded down from the NASA Official Website. The format of the ordered data was the *.HDF (Hierarchical Data Format) and can't be input to the model directly, so these data format was changed into the *.ASC format by using some software as Mosdis Reprojection Tools (MRT) and ArcGIS.(2)Improving and validating the Nishida ModelAccording to the actual situations of China, the Nishida Model was improved: 1) The soil water content was added into the factor to simulate the regional ET; 2) Based of the available information, the formula of calculating the crop canopy resistance and the aerodynamics resistance have been changed; 3) The remote sensing temperature from MODIS was separated into the land surface temperature and the vegetation canopy temperature by the vegetation cover index. The modified model was composed of three sub-models as the available energy of land surface, soil evaporation fraction and the...