A methodology for the analysis of land surface control on evapotranspiration and heat fluxes is presented, based on the assimilation of remotely sensed data. The method is suitable for application in areas with limited data availability since only standard micro-meteorological measurements and land surface temperature maps are required, while no a priori information about land cover is required. The land cover effect on the heat exchange is inferred from the assimilation in terms of heat transfer coef-ficients. The methodology has been applied in the Ethiopian Rift Valley where desertification processes are progressing at a high rate in association with remarkable temperatures recorded in the last decades. Measurements of radiation, temperature and wind profiles were taken in a field campaign. The land surface temperature maps were obtained from NOAA-AVHRR. The results show reasonable estimates of the retrieved surface fluxes and spatial patterns of heat transfer coefficients consistent with those of land cover and vegetation
