Dj. Cavalieri et al., REDUCTION OF WEATHER EFFECTS IN THE CALCULATION OF SEA-ICE CONCENTRATION WITH THE DMSP SSM I/, Journal of Glaciology, 41(139), 1995, pp. 455-464
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 var
iations 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 Nimb
us-7 scanning multi-channel microwave radiometer (SMMR) data through t
he 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 w
ith the special-sensor microwave imager (SSM/I) sensor is less success
ful. This results from the position of the 19.35 GHz SSM/I channels, w
hich 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 ch
annels are more sensitive to changes in atmospheric water vapor, which
results in greater contamination problems. An additional filter had b
een developed, based on a combination of the 19.35 and 22.2 GHz SSM/I
channels. Examples of the effectiveness of the new filter are presente
d and limitations are discussed.