Polarimetric scatterometer measurements at the Sea-ice Environmental Research Facility

A focused study on the C-band polarimetric scattering and physical characteristics of experimental sea ice was conducted at the Sea-ice Environmental Research Facility. Sea ice was grown in an outdoor pool outfitted with automated sensors to monitor environmental conditions. Radar measurements were sensitive to four distinct stages of development: (I) initial formation, (II) surface brine expulsion, (III) frost flower growth, and (IV) decimation. An optimal polarization and incidence angle was not readily apparent for the purposes of identifying the frost flower development stages I-III; however, low incidence angles appear to be most sensitive to the surface brine expulsion. Only the dual-polarization measurements at low incidence angles could be used to identify the onset of the decimation stage (IV). Backscatter increased rapidly during the initial formation, with a local maximum corresponding to ca. 80% areal coverage of frost flowers, followed by a local minimum when the surface was covered by a brine-rich surface layer, showing that surface brine expulsion may be identified using polarimetric scatterometry.