Balanço de Radiação no Bioma Caatinga no Semiárido Alagoano

Abstract

Knowing of the Net Radiation dynamic is crucial to determine the exchanges of energy that happen in the surface-atmosphere system. This research aimed to study the net radiation components dynamic pattern above a Caatinga vegetation. The study was carried out in a Caatinga vegetation area in the Mourão Farm (09º42,664’ S; 37º25,008’ W ; 165m) in Pão de Acúcar municipality, State of Alagoas, Northestern of Brazil. To carry out the micrometeorological monitoring a 6.5m height tower was installed throughout period from April/2019 to October/2020, in which the incoming solar radiation (Rg), reflected solar radiation (Rr), atmospheric long wave radiation and surface long wave radiation were measured by a CNR1 of Kipp e Zonen (Delft, Holanda) net radiometer. The hourly, daily and seasonal oscillation for each component of the net radiation were evaluated. The atmosphere had shown 66.47% partly cloudy through the experimental year. The values of albedo have shown small variation of its daily monthly average values among the dry and wet season. The Rn was estimated from Rg with good accuracy regardless of the year period. The Rn was dominated by the Rg, but had presented seasonal: higher during the dry season and lower in the wet season. The seasonal variation of the short wave components (Rg, Rr, BOC) depend on the atmospheric transmissivity and less from the surface albedo, meanwhile the long waves (Ra, Rs and BOL) depend on the effective emissivity of the atmosphere and the soil temperature (Rs).