Improving the spatial resolution of thermal bands based on downscale techniques and it’s effect on estimating the evapotranspiration of the reference plant

Due to technical limitations, most satellites cannot simultaneously collect images with high spatial, temporal, and spectral resolution. In this paper, the possibility of using DisTrade and TsHARP downscaling methods and STI-FM method in order to achieve high spatial resolution for MODIS and Landsat8 images was investigated. The RMSE value for sharpened images of 1 km to 30 meters was less than 3.93 ° C. In this study, the surface energy balance algorithm (SEBAL) was investigated to estimate the actual evapotranspiration distribution using a combination of Landsat 7 and MODIS satellite images based on the T-Sharp downscale method. The results showed that the integration of satellite images improved the accuracy of estimating actual evapotranspiration compared to Landsat 7 images. The mean squared error of estimated evapotranspiration during the growth period was determined in comparison with lysimetric data for Modis images of 1.24-2.91 mm / day and for integrated images of 0.81-1.1 mm / day. In general, the results of this study showed that the estimation of evapotranspiration using SEBAL algorithm and based on the combination of images with different temporal and spatial accuracy can provide acceptable results.