3-Decadal Changes in Sea Ice Melting and Freezing Pattern in Antarctica Using SSM/I Data

The present study aims to estimate the long term changes in sea ice areal extent (SIAE) around Antarctica using Special Sensor Microwave Imager (SSM/I) satellite data (1988–2011). Daily, weekly and monthly brightness temperature (T_B) maps of Antarctica have been generated. Temporal variation in monthly averaged T_B values of sea ice have been analyzed and an increasing trend is observed in T_B. Sea ice concentration (SIC) values are estimated and the concentration class 0.85–0.95 is observed as the main contributor in sea ice areal extent during the Antarctic peak winter month i.e. September and October. SIC changes rapidly from October onwards and shows fast melting of sea ice, however, from April start of freezing has been observed. Continuous increase in SIAE is observed from February to September in all the analyzed years (1988–2011) data. In this observation period maximum SIAE is observed in September 1989 and minimum in February 1993. The Moderate Resolution Imaging Spectroradiometer (MODIS) data is used for the validation of SIAE values. SSM/I and MODIS estimated SIAE values are compared (R²?=?0.98) and a relation between them is established by performing regression analysis. This relation is further used for the estimation of corrected SIAE values. The monthly average sea ice extent maps of last three decades have been analyzed and a shift in onset of freezing of sea ice has been observed. The period of frozen sea has also been observed as decreased.