Location
University of Utah
Start Date
6-19-1998 10:15 AM
Description
Polar sea ice plays an important role in the global climate. Although spaceborne scatterometers such as NSCAT have low inherent spatial resolution, resolution enhancement techniques can be used to increase the utility of NSCAT data in monitoring sea ice extent in the polar regions. Dual polarization radar measurement parameters, A and B, are used to identify sea ice and ocean pixels in composite images where A is CT0 normalized to 40° and B is the incidence angle dependence of CT0 • The A polarization ratio (AV / AH), vertical polarization B values, and CT0 estimate error variance of the vertically polarized data contain useful information about the presence of sea ice. The A polarization ratio and BV are used as primary classification parameters to discriminate between sea ice and open ocean. Estimates of the sea ice extent are obtained using linear and quadratic (Mahalanobis distance) discriminant boundaries on the bivariate distribution. The distribution parameters needed for the quadratic estimate are taken from the linear estimate. The CT0 error variance is used to reduce errors in the linear and Mahalanobis ice/ocean classifications. Noise reduction is performed through binary image region growing and erosion/dilation techniques. The algorithm is applied to NSCAT data. The resulting edge closely matches the NSIDC SSM/I derived 30% ice concentration edge.
Polar Sea-Ice Extent Detection Using Ku-Band Scatterometer Data
University of Utah
Polar sea ice plays an important role in the global climate. Although spaceborne scatterometers such as NSCAT have low inherent spatial resolution, resolution enhancement techniques can be used to increase the utility of NSCAT data in monitoring sea ice extent in the polar regions. Dual polarization radar measurement parameters, A and B, are used to identify sea ice and ocean pixels in composite images where A is CT0 normalized to 40° and B is the incidence angle dependence of CT0 • The A polarization ratio (AV / AH), vertical polarization B values, and CT0 estimate error variance of the vertically polarized data contain useful information about the presence of sea ice. The A polarization ratio and BV are used as primary classification parameters to discriminate between sea ice and open ocean. Estimates of the sea ice extent are obtained using linear and quadratic (Mahalanobis distance) discriminant boundaries on the bivariate distribution. The distribution parameters needed for the quadratic estimate are taken from the linear estimate. The CT0 error variance is used to reduce errors in the linear and Mahalanobis ice/ocean classifications. Noise reduction is performed through binary image region growing and erosion/dilation techniques. The algorithm is applied to NSCAT data. The resulting edge closely matches the NSIDC SSM/I derived 30% ice concentration edge.