Laboratory Studies of the Electromagnetic Properties of Saline Ice: Year 1 Experiments, Summary Submitted to the Office of Naval Research
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Date
1993-04
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Byrd Polar Research Center, The Ohio State University
Abstract
This report describes laboratory experiments conducted in early 1993 as part of the Sea Ice Electromagnetics Initiative of the Office of Naval Research. It is a follow-on document to the plan entitled Laboratory Studies of the Electromagnetic Properties of Saline Ice which established objectives and scheduling for the 1993 effort. The plan called for three measurement scenarios for 1993. These were: 1) collecting data on the microwave and optical properties of an undeformed ice sheet grown from the melt; 2) resolving the contributions of volume and surface scattering from an undisturbed and artificially roughened ice sheet; 3) studying the effects on microwave signatures of brine wicking on a snow covered ice sheet. Additional research included detailed laboratory studies of electrical properties of cores sent to several institutions around the country. A high priority of all the research efforts was to tightly integrate measurements of electrical properties with ice physical properties such as salinity, structure, brine pocket shape, etc. Other critical aspects of this phase of the project were to provide the modelling community with an opportunity to view the methods used to collect data, to provide preliminary results to all
members of the project in order to stimulate interaction between the modelers and the experimentalists as the experiment proceeded, and finally to provide well calibrated data for model validation. Experiments were conducted from January through April at the Cold Regions Research and Engineering Laboratory in Hanover, New Hampshire. Extensive use was made of the new outdoor Geophysical Research Facility as well as the indoor saline tank and refrigerated laboratories at CRREL. All three of the planned measurement scenarios were executed in both the indoor saline tank and in the Geophysical Research Facility. Additional, selected research was completed in the outdoor facility known as the lower pond. Highlights included the observation that a small amount of snow (less than 1 em thickness) appreciably changes the scattering response. Brine expulsion events were observed that may provide a basis for developing methods for detecting new thin (1 to 2 em) thick ice. Fully polarimetric passive microwave experiments were conducted along with measurements with an L-band radiometer. Continuous monitoring of the bulk dielectric constant (100Hz) was achieved. Laser beam spreading and transmission experiments were also conducted for the first time. Extensive measurements of surface and near surface properties including roughness (using a new photographic technique) and salinity were completed. Based on these observations, several questions have been raised about the physical properties of new sea ice. These are: 1) how is brine passed from the columnar zone of ice through the transition and frazillayers to the surface; 2) what is the distribution of brine in the transition and frazillayer; 3) what is the dielectric roughness of the ice surface during a brine expulsion event and what is dielectric roughness of the brine soaked snow?
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Keywords
Saline ice laboratory experiments, Sea ice laboratory experiments, Electromagnetic properties of sea ice, Sea Ice Electromagnetics Accelerated Research Initiative
Citation
Jezek, Kenneth C., editor. 1993. Laboratory Studies of the Electromagnetic Properties of Saline Ice: Year 1 Experiments, Summary Submitted to the Office of Naval Research. Byrd Polar Research Center Technical Note 93-04, Byrd Polar Research Center, The Ohio State University, Columbus, 70 pages.