2 Faculdade de Agronomia Universidade Federal do Rio Grande do Sul- UFRGS

Abstract. An accurate estimation of land surface temperature (LST) implies understanding of the energy/matter interactions and physical parameters that change in space and time into the biosphere. Additionally, the local physical conditions often makes the relation between air temperature (Tair) and LST a lot obscure. In this paper the authors compare a short-term monitoring of surface temperature and air temperature variations by means of two different night-time satellite overpasses. The main problem is to observe the relationship of LST and Tair by means of the multi-temporal satellite survey and ground based stations records. In order to quantify it, a simple linear regression to makes possible an operational understanding is developed. For the LST estimate it is used a published split-window algorithm. The Tair data were obtained from ground based stations under shelter. The LST and emissivity methods use both data collect from Advanced Very High Resolution Radiometer (AVHRR) instruments from National Oceanic and Atmospheric Administration (NOAA) satellites