Backscattering Analysis for Snow Remote Sensing Model With Higher Order of Surface-Volume Scattering

Abstract

Abstract-The study of earth terrain in Antarctica is important as this region has a direct impact on global environment and weather condition. There have been many research works in developing remote sensing technologies, as it can be used as an earth observation technique to monitor the polar region [11,15]. In previous studies, remote sensing forward model has been developed to study and understand scattering mechanisms and sensitivity of physical parameters of snow and sea ice. This paper is an extended work from previous studies [16][17][18][19], where an improved theoretical model to study polar region was developed. Multiple-surface scattering, based on an existing integral equation model (IEM) that calculates surface scattering and additional second-order surface-volume scattering, were added in the model from prior research works [7] for improvement in the backscattering calculation. We present herein the application of this model on a snow layer above ground which is modeled as a volume of ice particles that are closely packed and bounded by irregular boundaries above a homogenous half space. The effect of including multiple surface scattering and additional surface-volume scattering up to second order in the backscattering coefficient calculation of snow layer is studied for co-polarized and cross-polarized returns. Comparisons with satellite data are also done for validation. Results show improvement in the total backscattering coefficient for cross-polarized return in the studied range, suggesting that multiple-surface scattering and surface-volume scattering up to second order are important scattering mechanisms in the snow layer and should not be ignored in polar research.

Backscattering Analysis Utilizing Relaxed Hierarchical Equivalent Source Algorithm (RHESA) for Scatterers in Vegetation Medium

“…In future, this study can be extended to a layer or to layers of scatterers, as in real vegetation media, with the ability to model more realistic shapes of scatterers. By combining the RHESA with radiative transfer theory solution and DMPACT, the total backscattering return from layers of dense media can be modelled as in previous studies [2,5,7,8,11], but with more accurate results for vegetation media.…”

“…Theoretical models in microwave remote sensing research have been developed using analytical methods that employ approximation models [1][2][3][4][5][6][7][8][9][10][11][12], especially for vegetation media [9][10][11][12]. Analytical method models can provide some physical insight into media, and allow the study of scattering behaviour for variations in parameters; however, their accuracy is limited, as this is carried out by approximating the scatterers into limited shapes such as spheres, cylinders, needles, ellipsoids, and elliptic discs.…”

Polarization ratio characteristics of electromagnetic scattering from sea ice in polar areas

“…where k is the wave number, k x = k sin θ cos φ , k y = k sin θ sin φ , k z = k cos θ , k sx , k sy and k sz have similar definitions by replacing θ and φ with θ s and φ s , pp represents VV or HH polarization, S(θ , θ s ) is the shadowing function defined by Sancer [31] (Appendix A), σ is the RMS height of the surface, W n is the Fourier transform of the n-th power of the surface correlation coefficient (Appendix B), and the expression for I n pp is given in Appendix C. Top surface scattering can be expressed as…”

“…The shadowing function proposed by Sancer [31] is a function of incident angle, θ , scattering angle, θ s , and surface root mean square slope, σ s , which can be written in the following form: where erfc is the error-function complement related to the error function erf by…”

“…They developed an algorithm for retrieving the ice thickness, which is based on the backscattering ratio and IEM. In Syahali and Ewe's work, [31] multiplesurface scattering, based on IEM that calculates surface scattering and additional second-order surface-volume scattering, was added into the model (based on prior studies) for improvement in the backscattering calculation.…”