A new method for medium-resolution sea ice analysis using weather-influence corrected Special Sensor Microwave/Imager 85 GHz data

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2004
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  • A detailed description of a new method for sea ice analysis using Special Sensor Microwave/Imager (SSM/I) brightness temperature measurements (SEA LION algorithm) is given. The SEA LION algorithm uses the normalized brightness temperature polarization difference at 85 GHz. This polarization difference is corrected for the change in brightness temperatures due to sea surface scattering and absorption/emission by atmospheric water (weather influence). This is achieved by taking low-frequency SSM/I data and Numerical Weather Prediction model data for radiative transfer calculations. Tie points are derived from 85 GHz SSM/I data over a period of at least 10 days/one month focused around the period of investigation. The difference between measured and modelled polarization difference is minimized by iteration to obtain the sea ice concentration. The SEA LION algorithm was applied to daily gridded and single overpass 85 GHz SSM/I data. Resulting 12.5 km × 12.5 km ice concentrations are compared to those of the NASA-Team and the COMISO-Bootstrap algorithms, to ship observations, and to space-borne visible/infrared (VIS/IR) and active microwave imagery. The SEA LION algorithm ice edge agrees within 10 km with VIS/IR imagery. The across ice-edge SEA LION algorithm ice-concentration gradient is considerably steeper than that of the NASA-Team and COMISO-Bootstrap algorithm ice concentration and agrees with active microwave imagery. Arctic SEA LION ice concentrations compare to those obtained from classified active microwave imagery with a correlation (regression) coefficient of 0.84 (0.77) and a difference of -4.4% (NASA-Team algorithm: 0.85 (0.57) and -8.5%). © 2004 Taylor & Francis Ltd.
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  • info:eu-repo/semantics/closedAccess
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Forschungsinformationssystem der UHH
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oai:www.edit.fis.uni-hamburg.de:publications/d11c0019-4a1a-4f31-963f-d98456bdce0d