Radar Sensing of SEA ICE at the Small Incidence Angles: Simulation and Comparison of the Different Approaches.

Orbital radars are widely used to investigate ice cover, but measurements are usually made at the middle incidence angles (20°-60°). In this study the problem of ice cover monitoring at the small incidence angles (0°- 18°) was considered. Two operating radars (DPR - Dual-frequency precipitation radar and SWIM - Surface Waves Investigation and Monitoring) and one promising radar (SKIM - Sea surface KInematics Multiscale monitoring) was analyzed. Numerical simulations of all radars were carried out and the assumption was confirmed that all radars can determine the kind of scattering surface (ice/open water) at the incidence angles less than 12°. The disadvantage of the DPR measurement scheme is that at incidence angles of 1 °_3° the problem may not have a solution. It deals with fact that ice and open water backscatter normalized radar cross sections (NRCS) will be the same. Due to the rotation of the antenna system around the vertical axis, this problem is solved in the SWIM and SKIM. However, the spatial resolution of SWIM is several times worse than that of DPR. Additional information is required to assess sea ice concentration (SIC).