The heterogeneity analysis on ground-based sites for evaluating satellite-derived LSTs

The ground-based sites are critical for assessing the uncertainties and evaluating the accuracy of the satellite-derived land surface temperature (LST) products by using the temperature-based validation (T-based) method. However, there is often a risk of the spatial mismatch between the observations of the satellite-sensor and the ground validation sites. Therefore the heterogeneity analysis of the ground-based sites, which can indicate the representativeness of the sites' observation, has been a basic and key stage in the whole process. The purpose of this paper is to analyses the heterogeneity of the ground sites based on the variogram function. In this study, the variograms of the eighteen sites in the Heihe River Basin (HRB) based on NDVI data were calculated to discuss the heterogeneities of these sites. Then according to the heterogeneity analysis results, these sites were leveled ground observation scale for validating satellite-derived LSTs.