Impact of changes in surface cover on energy balance in a tropical city by remote sensing: A study case in Brazil

Abstract

Cities are the most densely populated areas, making them the most used landscape by the population. The urbanization process drastically changes the land cover by converting natural vegetation into impermeable areas. The urban development of cities in the Brazilian Center-west region, such as the city of Cuiabá, was the result of migratory flows that changed the landscape without organization due to rapid urbanization. The impact of converting natural Cerrado areas to cities on energy balance and surface evapotranspiration is still unknown. Thus, the objective of this study was to evaluate the impact of changes in surface cover in Cuiabá on energy balance and evapotranspiration determined by remote sensing. The energy balance and evapotranspiration were estimated by SEBAL with images of TM Landsat-5 from April to November of 2009. The net radiation (Rn), soil/storage heat flux (G), sensible heat flux (H), latent heat flux (LE) and evapotranspiration (ET) estimated by remote sensing were validated by measurements performed on a micrometeorological tower installed in a pasture at the Experimental Farm of the Federal University of Mato Grosso. All the energy balance variables and ET estimated by SEBAL, except the G, were strongly correlated with measurements in loco and had low errors. The urban areas of Cuiabá had higher values of surface albedo and temperature, which reduced the Rn. The Rn was used primarily to H and G in Cuiabá. Still, an opposite pattern was observed in the forest and grassland areas, where the Rn was used primarily as a LE.