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Abstract
Monitoring the early stages of sea ice growth is vital because the changing sea ice cover controls the heat exchange between the ocean and air. New ice growth is also responsible for adding brine into the upper portion of the water column. Thin sea ice also significantly affects the albedo of the surface as it changes from a sea surface to an ice surface.
To investigate the ability of radars to map thin ice we performed radar backscatter measurements early in the fall freeze-up as part of the International Arctic Ocean Expedition '91 (IAOE'91(. We collected data over the thin ice types of light nilas, dark nilas, and pancake/slush ice using a ship-based, C-band FM radar with all four linear polarizations.
Our results indicate that radars must be able to measure σ0 as low as - 30 dB for VV polarization and - 34 dB for HH polarization. The noise-equivalent σ0 fortheERS-1 Synthetic-Aperture Radar is - 24 dB and for RADARS AT is -23 dB. This implies that these sensors are not capable of monitoring thin sea ice types such as dark nilas and grease ice but may be able to detect slightly thicker ice, such as light nilas and pancake ice, due to their higher backscatter.
