Ice-penetrating radar

Radioglaciology is the study of glaciers and ice sheets using radar. It employs a geophysical method similar to ground-penetrating radar that operates at frequencies in the MF, HF and VHF portions of the radio spectrum. Radioglaciology is sometimes referred to as "ice-penetrating radar" or "radio-echo sounding".

Glaciers are well suited to investigation by radar because the imaginary part of the permittivity of ice is small relative to its real part; this ratio is called the loss tangent. The conductivity of ice is small at radio frequencies, so its dielectric absorption is also small.

The primary goal of many radioglaciological surveys is to measure the thickness of a body of ice, which is an important boundary condition for ice-flow models. Ice thicknesses greater than 4 km have been measured in East Antarctica. Internal reflections have also been detected in many alpine glaciers and all modern ice sheets. These layers represent the internal stratigraphy and can also be used to constrain ice-flow models. The shapes of these internal reflections generally follow the bedrock topography and they are often assumed to be isochronous. Disturbances in these reflections that are unrelated to bedrock topography can be used to understand past ice flow, for example the anticlines arising from the Raymond Effect.

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