Characteristics of sea-ice thickness and snow-depth distributions of the summer landfast ice in Lu¨tzow-Holm Bay, East Antarctica

摘要

Sea-ice observations have been conducted on board icebreaker Shirase as a part of the scientific programs of the Japanese Antarctic Research Expedition. We summarize these to investigate spatial and interannual variability of ice thickness and snow depth of the summer landfast ice in Lu¨tzow-Holm Bay, East Antarctica. Electromagnetic–inductive observations, which have been conducted since 2000, provide total thickness distributions with high spatial resolution. A clear discontinuity, which separates thin first-year ice from thick multi-year ice, was observed in the total thickness distributions in two voyages. Comparison with satellite images revealed that such phenomena reflected the past breakup of the landfast ice. Within 20–30km from the shore, total thickness as well as snow depth decrease toward the shore. This is due to the snowdrift by the strong northeasterly wind. Video observations of sea-ice thickness and snow depth were conducted on 11 voyages since December 1987. Probability density functions derived from total thickness distributions in each year are categorized into three types: a thin-ice, thick-ice and intermediate type. Such interannual variability primarily depends on the extent and duration of the successive break-up events.