Inverse Reference Crop Evapotranspiration in the Ecological Agriculture Area of Qinghai Province Based on RS

Abstract：Based on the meteorological data collected from 15 weather stations in 2003 in the ecological agriculture area of Qinghai Province,the reference crop evapotranspiration(ET0) was calculated by the FAO Penman-Monteith equation.Using the remote sensing image of MODIS elevation(DEM),land surface temperature(LST) and the normalized difference vegetation index(NDVI) were got by the French SPOT satellite,the remote sensing data could be extracted from them and coupled to the time resolution of ten-day,spatial resolution of 1 km.Then these data were used for the correlation analysis with ET0,and the inversion model of ET0 could be generated by using MATLAB software.At the same time,the regional ET0 remote sensing inversion model and its application conditions were got.The spatial distribution analysis of the ET0 calculated by the model from July to November in 2004 was finished with Arcgis9.3.The results of the study showed that: from Jul.to Nov.in 2003,the linear relationships between ET0 and the remote sensing factors of DEM,NDVI and LST were significant,and the linear relationship between ET0 and DEM was obvious negative correlation,and the linear relationships between ET0,NDVI and LST were very significant positive correlation.From the study,the multiple linear model of regional ET0 remote sensing inversion model was obtained,and passed the F and t significant inspection(α=0.01),so the model was extremely significant.The calculation and inversion results of 2004 illustrated that in space distribution ET0 increased from northwest to southwest direction,and decreased from low altitude to high altitude;the model inversion average relative error was 1.9%,which showed the model had a good inversion result.