A Novel Technique for Radar Depth Sounding of Fast Outlet Glaciers and Ice-Sheet Margins

The surface clutter simulator and the digital filter technique are developed for sounding and imaging of a subsurface stratified structure with arbitrary ice surface roughness of fast outlet glaciers and ice-sheet margins, which provides a new insight into the strong surface clutter reduction. The radar signal simulation method developed by employing Kirchhoff approximation of rough surface scattering and the ray tracing of geometric optics theory can give clear understanding of electromagnetic (EM) wave radiation and propagation through multilayer stratified media and support the interpretation of radar actual observations for retrieving good information on ice bed and internal layers. The radar sounder echo simulator can calculate the EM scattering from ice internal multilayer rough interfaces and identify whether deeper layers or ice-bed nadir echoes masked by a strong surface off-nadir echo still return to the radar receiver or not, which offers an important tool for designing and optimizing radar system performance. The numerical spline interpolation technique is proposed to discretize the 3-D real ice topography into a suitable triangulated mesh for obtaining higher accurate radar simulation data compared with the facet method. The digital filter technique can be complementary to conventional processing methods in order to distinguish an ice bed from a strong surface clutter with an extremely crevassed rough surface in Antarctica and Greenland. Ice data processing results of certain outlet glaciers' topography are demonstrated. The presented unified data analysis methodology can be also applied to planetary exploration.