Modelling Changes in Scattering Properties of the Dielectric and Young Snow-Covered Sea Ice at GHz Requencies

Abstract

ABSTRACT. Observations of the physical properties of the snow cover and underlying young fast ice in Resolute Passage, N.W .T., Canada, were made during the winter of 1982. Detailed measurements of snow density, and ice and snow temperatures, salinities, and brine volumes were made over a period of 46 d, beginning when the ice was 0.4 m thick and about 8 d old. The recorded values are used in a theoretical mixture model to predict the dielectric properties of the snow cover over the microwave frequency range. The results of this analysis are then used to investigate the effects of the snow properties on the radar back-scatter signatures of young sea ice. The results show that back-scatter is a function of the incidence angle and can change significantly over short periods of time during the early evolutionary phase of ice and snow-cover development. This has important consequences for the identification of young ice forms from Synthetic Aperture or Side Looking Airborne Radar images.

Weekly gridded Aquarius L-band radiometer/scatterometer observations and salinity retrievals over the polar regions – Part 2: Initial product analysis

“…At C band, it was shown that the NRCS variation to changes in ice properties (such as brine volume and wetness) depends on the incidence angle (Scharien et al, 2010). Using brine-snow dielectric parameterizations based on a dielectric mixture model for snow with brine inclusions (Drinkwater and Crocker, 1988), dry-snow permittivity increases as brine volume increases, temperature increases, and density increases. Brine volume has the largest influence on the permittivity of dry snow.…”

An iterative approach to multisensor sea ice classification

“…The source of the discrepancy is likely due to frost flower formation on the surface of smooth ice. Drinkwater and Crocker [27] found that frost flower formation can yield microwave signatures that are similar to RFY ice. The proposed classifier did not include a separate classification cluster for this ice type.…”

Ku-, X- and C-Band Microwave Backscatter Indices from Saline Snow Covers on Arctic First-Year Sea Ice

“…Snow density ( ; sampled using a 66.35 cm 3 density cutter with an accuracy of ±0.01 g), snow temperature ( ; measured using a 0.1 °C resolution Digi-Sense RTD thermometer probe at an accuracy of ±0.2 °C), snow salinity ( ; measured using a WTW Cond 330i conductivity meter with an accuracy of ±0.5%) and snow grain radius ( ; measured from disaggregated snow grains on a 2 mm grid crystal plate and classified following [23] were sampled from all three snow covers, sampled every 2 cm in vertical profile. Post-measurement destructive snow sampling (including snow thickness and thermophysical measurements) of the scatterometer scan area revealed that the snow cover was consistent with the adjacent snow pit used for sampling snow thermophysical measurements.…”

“…Field measurements from the three snow thicknesses show a highly saline bottom 4 cm basal layer (~6-~20 parts per thousand (ppt)) consisting of somewhat-rounded depth hoar crystals (Tables 1-3). High salinities in the basal snow layers are due to significant upward brine wicking [16,23,24]. The presence of brine throughout the snow cover during the late winter season are less commonly observed as snow covers are brine-wetted usually during freeze-up, and snow covers overlaying highly saline frost flowers.…”

“…The presence of brine throughout the snow cover during the late winter season are less commonly observed as snow covers are brine-wetted usually during freeze-up, and snow covers overlaying highly saline frost flowers. [16,23].…”