Parametrização de modelos de radiação de onda longa atmosférica e balanço de radiação de ondas longas durante a estação chuvosa em área de Mata Atlântica no estado de Alagoas

Abstract

The analysis of the balance of radiation in forests is of fundamental importance, because through it it becomes possible to demonstrate how the ecosystem interacts with the atmosphere and what the possible impacts due to the replacement of the original vegetation, by urban areas, pastures, cultivated areas, etc. In addition, studies of the long-wave radiation balance in forested ecosystems are not commonly performed and for their study it is necessary to estimate them by physical and empirical models. The objective of this work was to estimate the longwave atmospheric radiation and the longwave radiation balance by means of the parameterization of estimation models under different cloud conditions during the rainy season in the Atlantic Forest area in the State of Alagoas. The data were obtained between April 7, 2017 and July 12, 2017 through sensors installed in a micrometeorological tower installed inside a fragment of the Atlantic Forest located in the municipality of Coruripe, Alagoas. The data of the estimated variables were calculated on the basis of equations and existing empirical models. The data were separated in different cloud conditions and later processed in hourly, daily and monthly averages. The estimation of the downward long-wave radiation was carried outusing the empirical models of Brunt (1932), Idso & Jackson (1969), Idso (1981) and Prata (1996) which were evaluated and parametrized for the study region. For the estimation of longwave radiation balance, the Penman-Brunt model was used, model which also underwent a process of evaluation and parameterization. The evaluation of the models was based on the analysis of mean absolute error, root mean square error, mean absolute percentage error, Pearson correlation coefficient and Willmott index of agreement. Before parameterization, the model of Idso (1981) was the one that had smaller statistical errors and higher correlation coefficient and concordance index. After the parameterization all the models presented improvements, without great difference when compared between each cloud condition. The Idso (1981) model had better performance in the general, partly cloudy sky condition and cloudy condition and the Idso & Jackson (1969) model in the condition of clear sky. In estimating the longwave radiation balance, before parameterization, the Penman-Brunt model presented a moderate performance without a significant difference between cloud conditions. After parameterization the model showed a slight improvement in its performance for all conditions. Therefore, it is concluded that the Idso model (1981) can be applied in any condition before parameterization. The model of Idso and Jackson (1969) can be applied, after parameterization, to clear sky conditions. It is believed that the Penman-Brunt model can be used without the need to be classified as cloudiness when in rainy periods.