C-Band Radar Polarimetry—Useful for Detection of Icebergs in Sea Ice?

摘要

This paper is focused on investigations of polarimetric C-band radar signatures of icebergs in sea-ice-covered ocean regions. The main objective is to assess the potential improvement of iceberg detection when using radar polarimetry. The dominant backscattering mechanisms of icebergs are deduced by evaluating different polarimetric parameters. Magnitudes of the cross-polarization ratios, the correlation coefficients between HH- and VV-polarized signals, and the entropy/alpha parameters indicate a strong contribution of volume scattering in many cases. Over most icebergs, the phase differences between HH- and VV-polarization are larger than zero. Spatial patterns of the polarimetric parameters differ from iceberg to iceberg and between different parameters. On some bergs, they only exhibit slight variations, whereas on others, they show noiselike textures, but also, more systematic changes are observed. Occasionally, radar intensities of icebergs are of similar magnitude as those of sea ice. Only for a number of these cases, the combined use of the investigated polarimetric parameters together with intensity improves the discrimination performance between icebergs and sea ice.