Antarctic Sea Ice Extent from ISRO’s SCATSAT-1 Using PCA and An Unsupervised Classification

Abstract

Indian Space Research Organisation’s SCATSAT-1 is a continuity mission for Oceansat-2 Scatterometer. The sensor works in a Ku-band (13.515 GHz) similar to the one flown on-board Oceansat-2. It provides backscattering coefficient over the globe and wind vector data products over the oceans that are useful for weather forecasting, cyclone detection, and tracking services. Besides backscattering coefficient (sigma nought), two other important parameters, namely, Gamma nought (obtained from backscattering coefficient) and Brightness temperature (obtained from scatterometer noise measurement) are given as the Level-4 data products archived at the ISRO’s Meteorological & Oceanographic Satellite Data Archival Centre. We used these three parameters both in horizontal and vertical polarizations for the Antarctic region (South Polar) to perform, first, a principal component analysis. Then, we used the first three principal components explaining the largest variability in the data set to perform an unsupervised ISODATA clustering classification to estimate the regions of sea ice around Antarctica. The derived sea ice extent through this method is compared with other popular sea ice extent products available elsewhere.