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

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.

Spatial and temporal variability of sea ice in the Laptev Sea: Analyses and review of satellite passive-microwave data and model results, 1979 to 2002

“…Other sources of error in the ice retrievals include possible effects such as thin ice (new ice, nilas, young ice), snow melt (increase of snow wetness, meltponding) and atmospheric effects (water vapor, liquid water), e.g. Grenfell et al (1992), Cavalieri et al (1995), Comiso and Kwok (1996), Fetterer and Untersteiner (1998). Values from both sea-ice data sets reveal no appreciable differences (Serreze et al, 2003).…”

Climatology of the Nordic (Irminger, Greenland, Barents, Kara and White/Pechora) Seas ice cover based on 85 GHz satellite microwave radiometry: 1992-2008

“…In order to mitigate this influence weather filters are applied. These are based on the approaches by Gloersen and Cavalieri (1986) and Cavalieri et al (1995), and use the low‐frequency SSM/I channels (19, 22 and 37 GHz) to filter out areas influenced by cloud liquid water and water vapour, respectively. This way most spurious ice over open water is removed.…”

A physical algorithm to measure sea ice concentration from passive microwave remote sensing data

“…Nevertheless, for various reasons, the techniques employed today to retrieve ice cover characteristics from passive microwave remote sensing data give significant errors (Agnew and Howell, 2003;Andersen et al, 2007;Carsey, 1992;Cavalieri et al, 1995;Comiso and Kwok, 1996;Fetterer and Untersteiner, 1998;Ivanova et al, 2014Ivanova et al, , 2015Meier, 2005).…”