Avaliação do saldo energético à superfície estimado por sensoriamento remoto em Pernambuco

Abstract

The management of natural resources such as fresh water has become one of the greatest challenges of the modern society. The smart and sustainable management of water resources requires the understanding of processes of dissipation, within a specific region, in different land surfaces. The SEBAL (Surface Energy Balance Algorithm for Land) has become a very useful tool to estimate the surface net radiation (Rn) in terms of regional and/or to areas where there is shortage of weather information. In this work were obtained data for net radiation with this algorithm and compared them with net radiation estimated from Global Solar Radiation (Rg), measures the surface. The global irradiance was obtained from Data Collection Platforms (DCP) automatic in the semiarid of Pernambuco, imaged on a clear day, in dry and rainy periods during the years 2007 and 2008. The Rn instantaneous computed by SEBAL, ranged from 473.3 to 708.8 Wm-2, at pixels where the stations are located. The deviations found between Rn instantaneous computed by SEBAL and estimated from the data of Rg from DCP decreasing, on average, from 8.7% to 3.3%, with more regional calibration of the internal parameters of the SEBAL. The correlation between the net radiation counted, with the SEBAL, regionalized to the low-middle São Francisco River basin and those estimated from measurements of Rg of PCD, got a R2= 0.84 with a root mean square deviation - RDQM = 26.8 Wm-2. After cropping a period of rainfall for the year in the cities Floresta, Arcoverde, Ibimirim, Serra Talhada and Caruaru, the correlation coefficient was 0.98 with a RDQM = 14.3 Wm-2 for the rainy season and 0.42 with a RDQM = 35.2 Wm-2 for the dry period. From the results, we propose perform calibration of the SEBAL input parameters for the State of Pernambuco, seeking them to determine the seasonality of solar radiation and intra-annual distribution of monthly rainfall throughout the state.