Evapotranspiration Estimation And Response To Underlying Surface And Meteorological Factors In Typical Areas Of Horqin Sandy Land

This paper takes the area of Aaqoura eco-hydrological test station of Tongliao City,Horqin Sandy Land,using Landsat remote sensing imagery and meteorological data,based on the METRIC model to the 2013-2016 growth season May-September surface feature parameters(surface temperature,soil thermal flux,albedo,leaf area index,vegetation index)and evapotranspiration(ET),By using the measured data of the eddy-related system in the test site,the inversion results were verified,and the temporal and spatial variations of surface energy and evapotranspiration in the research area were analyzed,and the influence degree of meteorological factors was analyzed,and the response relation of the surface characteristic parameters of the bottom surface was analysed.The following main conclusions are obtained through this study:1.The fitting results of the surface characteristic parameters and ET estimate and the vorticity measured values are all good,in which the fitting coefficient of diurnal vapor emission is 0.815,the RMSE is 1.084mm.The sensitivity analysis of the input data of METRIC model shows that ET on the parameters of the table in meadow and farmland area is sorted by:Ts>Albedo>LAI>NDVI;the sensitivity of ET to the table parameters in the dune area is sorted by:Albedo>Ts>NDVI>LAI,and the sensitivity to NDVI and Ts is less than meadows and farmland.2.The spatial distribution of surface characteristics and ET in the area under the analysis of the study region,the surface parameters and ET of each year are basically the same distribution trend,and the peak of the parameters of the table 7-8 months are generally evaporated and scattered.The LAI,NDVI and Rn of the growing season meadows and farmland are larger than the dune areas,in contrast to the Albedo and Ts in the dune areas,which are larger than meadows and farmlands,which lead to the greater of ET than the dune land in meadows and farmland areas.From the total average ET of the three-year growth season,the total ET of meadow and farmland are concentrated in 308mm-592mm;the total ET of the dunes are mainly concentrated below 300mm.The total ET in the dune area of the growing season 2016 was larger than in previous years,owing to the higher average temperatures and more rainfall.3.The effects of the net radiation,wind speed and air temperature on the ET of Meadow and dune were positively correlated,and there was a negative correlation between the ET and the relative humidity of meadow and dune.Taking the inversion of the surface parameters and evapotranspiration as an example,the corresponding image meta-value is extracted,and the vapor distribution is significantly negatively correlated with Ts,G and Albedo,and the correlation between LAI and NDVI is very significant.The meteorological factors are sorted by the size of ET contribution rate:net radiation>wind speed>air temperature>soil temperature>relative humidity.When the net radiation ? 179.19W/m2,the steam distribution is mainly influenced by the air temperature and relative humidity,when the air temperature?22.99 ?,the steam distribution is mainly constrained by wind speed and soil temperature.The size of the ET contribution rate is sorted by the surface characteristic parameters;NDVI>Albedo>LAI>Ts>G.