Antarctic iceberg calving monitoring based on EnviSat ASAR images

Abstract

Using full utilization of the high temporal and spatial resolution Environmental Satellite (EnviSat) Advanced Synthetic Aperture Radar (ASAR) data, we implemented a high-precision estimation of the annual calving area of Antarctic ice shelves, as well as an interpretation of the calving type. With EnviSat ASAR data which 40 times repeatedly covered the whole Antarctic coastline, we detected the location, type and occurrence time of iceberg calving events, and conducted statistical analysis on the temporal and spatial variation data with respect to the calving frequency and calving area of Antarctic ice shelves from August 2005 to August 2011. The results showed that (1 ) from 2005 to 2011, the mean annual calving area of Antarctica was 2969.7 km2, with a large varying amplitude of annual calving area and a slight decrease of the annual calving frequency; (2) the calving events of Antarctic ice shelves mainly occur from January to March, and most frequently in February; (3) the Wilkes Land located in East Antarctica is currently the area where iceberg calving occurs most frequently. The three major ice shelves, Ross, Filchner-Ronne and Amery ice shelf, are stable and calving events are rare. Ice shelves in the Queen Maud Land located in East Antarctica is relatively stable; (4) the frequency of iceberg calving with special scale less than 100 km 2 accounts for 94.1% of total frequency, and ignoring them will lead to an underestimation of the annual calving area of Antarctic ice shelves by 20.7% to 92.9% ; (5) the rift-opening calving (R-calving) whose main driving force is internal glacial stress is more frequent than the melt-related calving (M-calving) whose main driving force is the external atmospheric and oceanic factors, but the difference is not that large (about 10%).