Measurements of microwave emission from new and young saline ice during the 1993 CRREL pond experiment

摘要

The goals of this study were to observe multifrequency microwave brightness temperatures and emissivities in new and young saline ice, and to assess the effects of ice growth and structural changes on the microwave signatures. The authors were particularly interested in investigating the later stages of young ice growth for comparison with surface-based field observations of first-year (FY) and multiyear (MY) sea ice. Two particular points of interest were: (i) to compare certain roughened surfaces with an undisturbed surface evolving under the same growth conditions, and (ii) to isolate the changes in physical properties which accompany the transition of the microwave signature from young ice to FY ice. Young ice typically has a high polarization ratio (PRe) of about 0.08 as compared with values near 0.018 for FY and MY ice (Grenfell et al., 1992), where polarization ratio is defined as PR/sub e/(v)=[e(v, V)-e(v,H)]/[e(V, V)+e(v, H)], e is the ice emissivity as defined below, v is the observation frequency, and V and H refer to vertical and horizontal polarization respectively.