Land surface temperature estimation based on NOAA-AVHRR data during the HAPEX-Sahel experiment

Abstract

Accurate estimation of land surface temperature can be regarded as an important prerequisite of the global or regional monitoring of water, energy, and radiation budgets. An accurate estimation of land surface temperature involves correction for both the atmospheric and the surface emissivity effect. Combined ground truth, radiosonde and remote sensing data from the HAPEX-Sahel experiment have been used to evaluate three existing AVHRR-based split-window models designed for land surface temperature estimation and an algorithm for emissivity difference estimation. Local or regional model coefficients have been determined on the basis of simulated AVHRR measurements. The applied model for the emissivity difference determination turned out to be very sensitive under situations with medium to high water vapour content. It was found that results from the three models compared well except at large view angles. In semi-arid regions with high atmospheric water vapour content the atmospheric effect accounts for almost 90% of the correction whereas the emissivity effect typically accounts for 10%. An absolute evaluation was not performed, but comparison with ground truth data showed that the model-predicted temperatures were well within the expected range.