Dielectric permittivity and scattering measurements of Greenland firn at 26.5-40 GHz

Three blocks of snow approximately 33 cm on each side were harvested from the Greenland ice sheet at depths ranging from 0.3 to 2.7 m below the surface and brought back to the lab. A step frequency radar operated from 26.5 to 40.0 GHz was used to measure the wave velocity through the snow in three orthogonal directions. From these measurements, the relative permittivity was calculated; it varied with density from 1.69 to 1.91 and agreed well with other measurements on terrestrial snow. It was also found that the permittivity of the two deeper firn blocks was anisotropic by 4-7%. This anisotropy is explained by the elongation of the snow grains in the vertical direction. Extinction losses of about 5 dB/m were estimated by measuring the change in amplitude of signals propagating through the blocks. Although the estimated losses were highly variable, a minimum penetration depth of 87 cm into the firn was computed.<
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