GEOSAT Altimeter Sea-Ice Mapping
NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY STENNIS SPACE CENTER MS
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The 12 March 1985 GEOSAT launch enable satellite oceanographers to continue the earlier sea-ice monitoring shown to be feasible with the GEOS-3 and SEASAT altimeters 1. The large difference in return signals from a 13.5 GHz pulse over water versus over sea-ice permits the generation of an ice index that responds abruptly to sea-ice edges. Sample Arctic and Antarctic operational sea-ice index plots are shown, depicting the current effort within the Remote Sensing Branch at the Naval Ocean Research and Development Activity NORDA. This NORDA program provides graphical ice-index displays along GEOSAT nadir tracks to the NavyNational Oceanic and Atmospheric Administration NOAA Joint Ice Center JIC for assimilation into their sea-ice database. The altimeters all-weather capability has been an important addition to the JIC data bases, since cloud cover can drastically curtail visible and infrared viewing, and passive microwave data has coarser resolution. Ongoing research efforts are aimed at extracting additional sea-ice parameters from the altimeter waveform, which contain information on the reflecting surface. Possibilities include discrimination between water, land, ice, combination waterice, and waterland, as well as distinguishing various ice concentrations and possibly ice types. Coincident airborne passive microwave and synthetic aperture radar SAR data have been collected to test several methods which appear to be promising. Reprint.
- Snow, Ice and Permafrost