DOWNWARD LONGWAVE RADIATION ESTIMATES FOR CLEAR AND ALL-SKY CONDITIONS IN CENTRAL AMAZONIA

The downward longwave radiation (L↓), really is difficult of the net radiation the measured values component. Therefore, different parameterizations have been proposed to estimate it. Thus, in this study we evaluated the performance of various parameterizations for the L↓ flows estimated and their interaction with other variables measured as well as the air temperature and water vapour pressure interactions with L↓. In this study evaluates the performance of the downward longwave radiation parameters for clear and cloudy sky days applied in Central Amazonia region. The datasets used in this study was measured from micrometeorological tower controlled by Large Scale Biosphere Atmosphere experiment in Amazonia (LBA) from Manaus city, Amazonas. It was also found that precipitation and water vapour pressure exert enough on L↓ flows influence, especially in the wet season. The models for clear-sky conditions proposed, using their original coefficients trend to underestimate the L↓ flows measured. Best results for clear-sky were obtained with Idso & Jackson (1969), Brutsaert (1975) and Prata (1996) .