Conical electromagnetic waves diffraction from sastrugi type surfaces of layered snow dunes on Greenland ice sheets in passive microwave remote sensing

Abstract

Snow dunes on Greenland ice sheets are featured as Sastrugi surfaces, which have large heights at microwave remote sensing frequencies. They can also have large slopes. For this type of surfaces over multilayered snow structure, WindSat passive microwave polarimetric signatures have exhibited interesting polarimetric and angular signatures. In this paper, we study conical electromagnetic diffraction from Sastrugi surface that are modeled as ridged surfaces with random widths of the ridges. Then a surface integral equation with conical incident wave at a nonzero azimuthal angle is used to solve the surface fields. The surface integral equation is solved by method of moments (MoM). Because of the large rms heights of 7 wavelengths, there are more than 29,000 surface unknowns. Numerical results of the bistatic transmission coefficients from air to snow and from snow to air are studied. The effects of transmission beyond the critical angles are studied. The rough surface bistatic scattering properties are then incorporated in radiative transfer equations for 4 Stokes parameters of passive microwave wave remote sensing in layered snow, which is ready for the calculation of overall reflectivity and emissivity for 4 Stokes parameters.