An Antarctic monitoring initiative for fast ice and comparison with the Arctic

Abstract. While Arctic and Antarctic fast-ice observations are required by a number of interest groups for planning and logistical activities, or to support scientific research, obtaining those data is not trivial. Sea-ice extent is reasonably well observed using camera-based or satellite-borne instruments, however, in situ and satellite-based ice-thicknesss measurements remain a challenge. As the seasonal fast-ice thickness is directly linked to regional atmospheric and oceanographic conditions, monitoring of fast-ice thickness across a station network around Antarctica and in the Arctic is crucial to assess how climate change affects the polar system. The Antarctic Fast-Ice Network (AFIN) was recently established to provide the scientific community with fast-ice observations from sites operated by international contributors. Based on AFIN data a recent increase in interannual variability in annual maximum ice and snow thicknesses has been identified. Maximum Arctic fast-ice thickness generally exhibits a similar interannual variability, however, both positive and negative trends in ice thickness have been observed in the Arctic. Comparing the two hemispheres, we find that in the Arctic the fast ice establishes itself at a faster rate than in the Antarctic, where repeated cyclone action tends to intermittently remove the fast ice during autumn. Also, Arctic sites investigated here exhibit less snow cover than those from East Antarctic coastal sites.