FREIRE, M. L. F.; http://lattes.cnpq.br/6756464691141246; FREIRE, Morgana Lígia de Farias.
Résumé:
A physical model of atmospheric correction which considers the
influence of background contamination on the apparent reflectance of a target, is
implemented to evaluate the effects of molecular composition and aerosols in the
satellite imagery. The model simulates the signal detected by the sensor as a function
of successive orders of interaction of the solar radiation with the earth-atmosphere
system. It was applied to the images TM of LANDSAT-5, for the pixels on Sao
Goncalo reservoir, which is located in the interior of the State of Paraiba. The effect
of the adjacency is computed from the reflectance of the surface background
(vegetation + soil) and the functions related to the size of the target. The aerosol's
optical parameters (asymmetry factor, single scattering albedo) were obtained from
the literature. The optical depth is evaluated through the pyranometer data. Different
methods of solution of the Equation of Radiative Transfer (ETR) and, the aerosol's
phase functions were utilized to determine the intrinsic reflectance of the atmosphere.
The model is discussed by comparison with the reflectance data measured "in situ".
From the analyses of the results, the single scattering model used to determine the
atmospheric reflectance with the two-term approximation of Henyey-Greenstein for
the phase function of the aerosols, were selected. The reflectance values of water
evaluated for Sao Goncalo reservoir were satisfactory and they show clearly the
background influence. The model was also employed to simulate the planetary
reflectance detected from the sensors, considering the different characteristic targets
of the region under study. The results show that the atmospheric reflectance is
predominant for low reflectance targets and it is true even in the case of lower values
of the aerosol's optical depth. Exactly the opposite occurs in the case of the medium
reflectance targets where the predominant reflectance is that of the target.
