Effect of the Instrument Slit Function on Upwelling Radiance from a Wavelength Dependent Surface Reflectance

Abstract

The Radiance Enhancement (RE) method was introduced for efficient detection of clouds from the space. Recently, we have also reported that due to high reflectance of combustion-originated smokes, this approach can also be generalized for detection of the forest fires by retrieving and analyzing datasets collected from a space orbiting micro-spectrometer operating in the near infrared spectral range. In our previous publication, we have performed a comparison of observed and synthetic radiance spectra by developing a method for computation of surface reflectance consisting of different canopies by weighted sum based on their areal coverage. However, this approach should be justified by a method based on corresponding proportions of the upwelling radiance. The results of computations we performed in this study reveal a good match between areal coverage of canopies and the corresponding proportions of the upwelling radiance due to effect of the instrument slit function.

A Two-Domain MATLAB Implementation for Efficient Computation of the Voigt/Complex Error Function

“…Equation ( 11) deals only with a single point h 2 /π 2 for the parameter t and does not represent any practical interest. Therefore, further we will consider only two equations, Equations (10) and (12).…”

“…Further we will imply that the parameter y = Im[z] is always greater than zero. The real part of the complex error function K(x, y) is known as the Voigt function [1][2][3][4] that is widely used in Atmospheric Science to describe emission and absorption of the photons by atmospheric molecules [5][6][7][8][9][10][11][12]. Specifically, the Voigt function is used to compute wavelength-dependent absorption coefficients by using the HITRAN molecular spectroscopic database [13].…”

A two-domain MATLAB implementation for efficient computation of the Voigt/complex error function

“…Further we will imply that the parameter y = Im [z] is always greater than zero. The real part of the complex error function K (x, y) is known as the Voigt function [1][2][3][4] that is widely used in Atmospheric Science to describe emission and absorption of the photons by atmospheric molecules [5][6][7][8][9][10][11][12]. Specifically, the Voigt function is used to compute wavelength-dependent absorption coefficients by using the HITRAN molecular spectroscopic database [13].…”