Reduction of weather effects in the calculation of sea-ice concentration with the DMSP SSM/I

• Published in: Journal of Glaciology
• Main Authors: Cavalieri, Donald J., St. Germain, Karen M., Swift, Calvin T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1995
• Subjects: Journal of Glaciology; Sea ice
• Online Access: http://dx.doi.org/10.1017/s0022143000034791; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000034791

Abstract A problem in mapping the polar sea-ice covers in both hemispheres has been the sporadic false indication of sea ice over the open ocean and at the ice edge. These spurious sea-ice concentrations result from variations in sea-surface roughening by surface winds, atmospheric water vapor and both precipitating and non-precipitating liquid water. This problem was addressed for sea-ice concentrations derived from the Nimbus-7 scanning multi-channel microwave radiometer (SMMR) data through the development of a weather filter based on spectral information from the 18.0 and 37.0 GHz vertical polarization SMMR channels. Application of a similar filter for use with sea-ice concentration maps derived with the special-sensor microwave imager (SSM/I) sensor is less successful. This results from the position of the 19.35 GHz SSM/I channels, which are closer to the center of the 22.2 GHz atmospheric water-vapor line than are the SMMR 18.0 GHz channels. Thus, the SSM/I 19.35 GHz channels are more sensitive to changes in atmospheric water vapor, which results in greater contamination problems. An additional filter has been developed, based on a combination of the 19.35 and 22.2GHz. SSM/I channels. Examples of the effectiveness of the new filter are presented and limitations are discussed.