(Table 1) Iceberg characteristics and start and end date and location of iceberg buoys in the Weddell Sea

The drift of 52 icebergs tagged with GPS buoys in the Weddell Sea since 1999 has been investigated with respect to prevalent drift tracks, sea ice/iceberg interaction, and freshwater fluxes. Buoys were deployed on small- to medium-sized icebergs (edge lengths <= 5 km) in the southwestern and eastern Weddell Sea. The basin-scale iceberg drift of this size class was established. In the western Weddell Sea, icebergs followed a northward course with little deviation and mean daily drift rates up to 9.5 ± 7.3 km/d. To the west of 40°W the drift of iceberg and sea ice was coherent. In the highly consolidated perennial sea ice cover of 95% the sea ice exerted a steering influence on the icebergs and was thus responsible for the coherence of the drift tracks. The northward drift of buoys to the east of 40°W was interrupted by large deviations due to the passage of low-pressure systems. Mean daily drift rates in this area were 11.5 ± 7.2 km/d. A lower threshold of 86% sea ice concentration for coherent sea ice/iceberg movement was determined by examining the sea ice concentration derived from Special Sensor Microwave Imager (SSM/I) and Advanced Microwave Scanning Radiometer for EOS (AMSR-E) satellite data. The length scale of coherent movement was estimated to be at least 200 km, about half the value found for the Arctic Ocean but twice as large as previously suggested. The freshwater fluxes estimated from three iceberg export scenarios deduced from the iceberg drift pattern were highly variable. Assuming a transit time in the Weddell Sea of 1 year, the iceberg meltwater input of 31 Gt which is about a third of the basal meltwater input from the Filchner Ronne Ice Shelf but spreads across the entire Weddell Sea. Iceberg meltwater export of 14.2 × 103 m3 s-1, if all icebergs are exported, is in the lower range of freshwater export by sea ice.

本研究针对1999年以来在威德尔海（Weddell Sea）部署GPS浮标标记的52座冰山的漂移特征展开调查，重点关注其主流漂移路径、海冰-冰山相互作用及淡水通量。浮标被部署在威德尔海西南部与东部的中小型冰山（边长≤5km）之上，本研究确立了该尺寸等级冰山的盆尺度漂移规律。在威德尔海西部，冰山整体沿北向漂移，偏移量极小，平均日漂移速率可达9.5±7.3 km/d。在西经40°以西区域，冰山与海冰的漂移保持同步；该区域海冰覆盖率达95%，为高强度固结的多年海冰区，海冰对冰山起到了导向作用，这也是漂移路径保持同步的原因。而在西经40°以东区域，浮标的北向漂移会因低压系统过境出现大幅偏移，该区域的平均日漂移速率为11.5±7.3 km/d。通过分析专用传感器微波成像仪（Special Sensor Microwave Imager, SSM/I）与地球观测系统先进微波扫描辐射计（Advanced Microwave Scanning Radiometer for EOS, AMSR-E）的卫星反演海冰浓度数据，本研究确定了海冰与冰山同步漂移的海冰浓度下限阈值为86%。同步漂移的空间尺度估计至少可达200km，约为北冰洋同步漂移尺度的一半，但比此前研究提出的数值高出一倍。基于冰山漂移模式推导的3种冰山输出情景估算的淡水通量具有显著变异性。假设冰山在威德尔海的过境时长为1年，则其融水输入量可达31吉吨（Gt），约为菲尔希纳-龙尼冰架（Filchner Ronne Ice Shelf）底部融水输入量的三分之一，且该融水会扩散至整个威德尔海。若所有冰山均完成输出，则冰山融水的输出通量可达14.2×10³ m³/s，该值处于海冰淡水输出通量的下限区间。