Efeito das propriedades microclimáticas na emissão de onda longa pela atmosfera em área de Cerrado Campo Sujo

Abstract

In this study we analyzed the performance of the Brunt (1932), Swinbank, (1963), Idso & Jackson (1969), Brutsaert (1975), Idso (1981), and Bignami et al. (1995) methods to estimate atmospheric emissivity and long wave radiation under grass-dominated savannas (known as Campo Sujo Cerrado), in the region of Baixada Cuiabana. The estimates were compared with data obtained by the radiation and energy balance equations in two seasons, dry season (May to August), and wet season (September to December) of 2009. The Swinbank and Idso & Jackson methods, that consider only air temperature, show better performances for wet season. However, methods that consider water vapor pressure and air temperature (Brunt, Brutsaert, Bignami and Idso) show good performances for dry season. Idso and Brutsaert methods show the highest index of agreement for the place and period studied, obtaining the highest indexes of agreement, probably due to the occurrence of lower thermal amplitudes and the variation of the amount of vapor of the atmosphere during the day, thus demonstrating the sensitivity of these equations to the variation of the air temperature and especially the sky conditions.