Fragmentation patterns of Antarctic icebergs in sea ice: observations and statistical data

Fragmentation is a key process in Antarctic iceberg decay, influencing the Antarctic climate and ecosystems. However, iceberg fragmentation has not been quantified at the pan-Antarctic scale. Using Sentinel-1 data from August to October 2019, we identified 407 fragmentation events in the circum-Antarctic near-coastal zone, with original iceberg sizes ranging from 0.01 km² to 5591.34 km². The Indian Ocean sector had the greatest number of fragmented events, 97% of which involved icebergs less than 1 km², whereas the Bellingshausen–Amundsen Sea sector has experienced the highest number of fragmentation events involving medium to large icebergs. Smaller icebergs (less than 1 km²) were more susceptible to disintegration through highly fractured capsizing, whereas larger icebergs underwent disarticulation. Fragmentation events were less frequent in landfast ice or mélange (∼0.5% monthly), whereas icebergs exceeding 10 km² exhibited a notable increase in the ratio of fragmentation events to the total number of icebergs (more than 15% monthly) when they were in motion and rotating in pack ice. Our findings indicate that during winter and under extensive sea ice cover, internal ocean waves, ocean currents and collisions are key factors influencing iceberg fragmentation.

冰山碎裂是南极冰山衰减过程中的核心过程，其对南极气候与生态系统均具有显著影响。然而目前尚未在泛南极尺度上对冰山碎裂事件进行量化研究。本研究借助2019年8月至10月的哨兵-1号（Sentinel-1）遥感数据，在环南极近岸海域共识别出407起冰山碎裂事件，原始冰山面积介于0.01平方千米至5591.34平方千米之间。印度洋扇区的碎裂事件数量最多，其中97%的事件涉及面积小于1平方千米的冰山；而别林斯高晋海-阿蒙森海扇区则是中大型冰山碎裂事件发生最多的区域。面积小于1平方千米的小型冰山更易通过高度碎裂后的倾覆发生解体，而大型冰山则以分离式崩解为主。在固着冰或碎冰混合体（mélange）区域内，冰山碎裂事件的发生频率较低（月均约0.5%）；而当面积超过10平方千米的冰山在浮冰群中移动并旋转时，其碎裂事件占该类冰山总数的比例会出现显著上升，月均占比超过15%。本研究结果表明，在冬季且海冰覆盖范围广泛的条件下，海洋内波、海流以及碰撞是影响冰山碎裂的关键因素。