Emission from an inhomogeneous layer with irregular interfaces

Abstract

A theoretical model for microwave emission from an inhomogeneous layer has been developed using the radiative transfer method. The top and bottom boundaries of the layer are assumed to be randomly rough surfaces, and the scatter characteristics are assumed to be describable by the Kirchhoff scatter model. The presence of an irregular top boundary is found to cause a slower angular trend than the case of a plane layer and causes, in addition, a rise in temperature if the layer permittivity is large. On the other hand, if only the bottom boundary of the layer is rough, a rise in emission is observed relative to the plane layer. When both the top and the bottom boundaries are rough, the emissions at small nadir angles are closer to those of a layer with a rough bottom boundary, and the emissions at large nadir angles are closer to those of a layer with a rough top boundary. A comparison of the layer model with reported angular measurements from a snow layer at three different frequencies and polarizations shows promise for such a model. An additional comparison of emission versus the depth of a snow pile indicates that an irregular snow ground interface causes higher emissions at small depths. This fact is necessary to explain the observed measurements.

WindSat Passive Microwave Polarimetric Signatures of the Greenland Ice Sheet

“…4(a)]. We note that in the horizontal polarization plotted in the top right panel, scatter in the data are large, more than 8 K, which overwhelms any similar small azimuthal modulations on the order of 1-2 K. The large scatter in horizontal brightness temperatures and the relatively small dynamic range in vertical polarization are consistent with previous theoretical and experimental studies [13], [31].…”

Passive microwave methods to retrieve snow pack characteristics in the UK

“…In wet snow, the upwelling electromagnetic radiations and brightness temperatures are no longer depressed at high frequencies and it is difficult to distinguish snow from non-snow surfaces. In previous studies research grotips have used a physically based emissivity model to predict the emission behaviour of a snow pack (Chang et oL 1976;Kong et aL 1979;Fung & Chen. 1981;Tiuri.…”

Microwave Emission From Two-Dimensional Inhomogeneous Dielectric Rough Surfaces Based on Physics-Based Two-Grid Method

“…Understanding of electromagnetic wave scattering and emission from a two-dimensional inhomogeneous dielectric rough surface are of interest to both remote sensing (soil moisture, sea ice, frozen land, etc.) and optical imaging [1][2][3][4][5][6][7][8][9][10][11][12]. Among the various numerical methods, Pelosi and Coccioli [13] applied a finite element method based on perturbation formulation to deal with one-dimensional slightly rough surfaces with multiple scattering being neglected.…”