Imaging and sounding of ice fields with airborne coherent radars

The recent development of the synthetic aperture imaging radar [Brown and Porcello, 1969; Harger, 1970; Rihaczek, 1969], which generates high-resolution surface imagery from an airborne or spaceborne platform, has generated interest in the scientific community for its use as an all-time all-weather remote sensor to study the earth's solid surface, oceans, and polar regions [Bradic, 1967; Waite and MacDonald, 1970; Brown et al., 1973]. The radar echo is a 'signature' of the characteristics of the reflecting surface and immediate subsurface layer: roughness, slope distribution, dielectric constant, and layering. The penetration property of the radio waves allows a radar system to detect subsurface layers. A unique capability of the imaging radar is that it is an allweather all-time sensor because it provides its own illumination and usually operates in the microwave region of the electromagnetic spectrum to which clouds are transparent. In this paper we present a number of observations collected with the Jet Propulsion Laboratory (JPL) L band (i.e., 25-cm wavelength) imaging radar and VHF (2-m wavelength) sounder. Specific data presented are sounding data taken over Greenland showing layering down to a depth of about 100 m and radar imagery of glaciers in southeast Alaska, nearcoast ice in northern Alaska, and sea ice cover in the Beaufort Sea.