The structure and salinity characteristics of saline ice slabs removed from ice sheets grown in an outdoor pool have been studied and related to the complex relative dielectric permittivity measured, utilizing free space transmission techniques, at 4.8 and 9.5 GHz. The saline ice closely simulated Arctic sea ice in its structural and salinity characteristics which were regularly monitored in a number of ice sheets grown during the winters of 1983--1984 and 1984--1985. In-situ transmission measurements at similar frequencies were also made on the ice sheet itself using antennas located above and beneath the ice. The slab measurements were made during warming from -28¿ C to -2¿ C on slabs grown during the winter of 1983--1984 (4.75 GHz) and during a warming and cooling cycle over a slightly larger temperature range on slabs grown during the winter, 1984--1985 (4.80 and 9.50 GHz). The 1983--1984 results show both the real &egr;r' and imaginary &egr;r' parts to vary almost in direct proportion to the brine volume vB at values less than about 50%0. The 1984--1985 slabs showed only &egr;r' to depend strongly on vB while values of &egr;r' were considerably less than in the previous year.

This difference may have been due to greater electrical conductivity in the 1983--1984 slabs, which could be related to distinct differences seen in brine pocket structure between the two winters. Values of &egr;r' as a function of vB were slightly lower on the average at 9.50 GHz than at 4.80, and most values of &egr;r' agreed with the results of others when their temperature and salinity values were converted to values of vB. Changes in &egr;r' due to thermal modification (laboratory warming) seem more strongly related to a gain in air volume due to drainage than to the redistribution of brine inclusions.

The in-situ measurements showed extremely high attenuation for the young (<12 cm) brine-rich ice. Good agreement was found between data for the more desalinated samples and theoretical values predicted by a previously proposed dielectric mixing model that was modified to account for the brine pocket geometry observed in thin sections, and also by including a bulk conductivity term to account for the observed loss.