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Thin Sea-Ice Thickness as Inferred from Passive Microwave and In Situ ObservationsSince microwave radiometric signals from sea-ice strongly reflect physical conditions of a layer near the ice surface, a relationship of brightness temperature with thickness is possible especially during the early stages of ice growth. Sea ice is most saline during formation stage and as the salinity decreases with time while at the same time the thickness of the sea ice increases, a corresponding change in the dielectric properties and hence the brightness temperature may occur. This study examines the extent to which the relationships of thickness with brightness temperature (and with emissivity) hold for thin sea-ice, approximately less than 0.2 -0.3 m, using near concurrent measurements of sea-ice thickness in the Sea of Okhotsk from a ship and passive microwave brightness temperature data from an over-flying aircraft. The results show that the brightness temperature and emissivity increase with ice thickness for the frequency range of 10-37 GHz. The relationship is more pronounced at lower frequencies and at the horizontal polarization. We also established an empirical relationship between ice thickness and salinity in the layer near the ice surface from a field experiment, which qualitatively support the idea that changes in the near-surface brine characteristics contribute to the observed thickness-brightness temperature/emissivity relationship. Our results suggest that for thin ice, passive microwave radiometric signals contain, ice thickness information which can be utilized in polar process studies.
Document ID
20070034151
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Naoki, Kazuhiro (Chiba Univ. Chiba, Japan)
Ukita, Jinro (Chiba Univ. Chiba, Japan)
Nishio, Fumihiko (Chiba Univ. Chiba, Japan)
Nakayama, Masashige (Kushiro Chilrend's Museum Hokkaido, Japan)
Comiso, Josefino C. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Gasiewski, Al (National Oceanic and Atmospheric Administration United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2007
Subject Category
Earth Resources And Remote Sensing
Distribution Limits
Public
Copyright
Public Use Permitted.

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