Estimativa do saldo de radiação na região semiárida da Paraíba por meio de sensoriamento remoto orbital.

Abstract

The total energy falling on the surface, directly affects the radiation balance at the surface in different ways, depending on biogeophysical aspects. Obtaining of energy flows makes it possible to study the temporal dynamics of a specific region, but it is not always possible to obtain such data, due to the limited number of micrometeorological stations and / or available. Therefore, it becomes possible to estimate these flows, as well as vegetation indices using satellite images. The objective of this study is to prove the effectiveness of product MODIS / Terra to estimate the net radiation for the semi-arid region of Paraiba, which is a region dominated the Caatinga biome, without the use of auxiliary surface data. Images were used referring to days order of year 25, 33, 57, 65, 81, 105, 137, 169, 193, 209, 217, 233, 249, 281, 289, 313, 329 and 361, the year 2013 that cover the state of Paraíba. The methodology used was based on equations proposed by Bisht and Bras (2011). The validation of the results was performed with two micrometeorological towers experimental data, both are located in preserved and degraded area, located in the city of Campina Grande, Paraiba. To get to the result of the instantaneous net radiation, computed albedos were used in two ways: using the MCD43-A3 and the MOD09-A1. The albedo values were higher in degraded areas. Although estimates have been overestimation and underestimation, it was possible to prove the effectiveness of MODIS Product ready albedo, MCD43-A3, with EMP 16.48% for the radiation balance and the EMA was 79.95 W / m²; on the other hand, the balance obtained with the MOD09-A1 was more suitable for the preserved area with EMP 16.91% and EMA of 94.35 W / m² for the degraded area. The NDVI showed a negative correlation with the radiation balance.