Observation of wave propagation over 1,000 km into Antarctica winter pack ice

A drifting wave-ice buoy (Medusa-766) was deployed at the Lützow-Holm Bay (LHB) marginal ice zone in Antarctica during the 63rd Japanese Antarctic Research Expedition to study the wave influence on the unstable LHB fast ice. Medusa-766 survived the Antarctic winter as it was located deep in the ice cover with the shortest distance to the ice-free Southern Ocean over 1,000 km; at this time, there was evidence of 8-cm-height wave signal at the buoy position. Using the the ECMWF’s reanalysis wave data, we show that the incoming waves were likely 4-m waves that were generated by an extratropical cyclone in the Southern Ocean. Wave-induced ice breakup potential for this event could extend hundreds of kilometres into the ice field. When Medusa-766 was in LHB in the summer months, it did not detect sizable wave energy despite the low sea ice concentration extent even during on-ice wave events. Understanding the wave attenuation characteristics is needed to elucidate the ocean wave effect to the unstable LHB fast ice. The success of Medusa-766 demonstrates the robustness of the general design and the high sensitivity of the sensor used, which is promising for future LHB wave–ice interaction research.本研究依托第63次日本南极考察队，在南极吕佐夫-霍尔姆湾（Lützow-Holm Bay, LHB）海冰边缘区（marginal ice zone）部署了一台漂流式波浪-海冰浮标（Medusa-766），旨在探究波浪对该区域不稳定固定冰（fast ice）的影响。Medusa-766顺利度过南极冬季：其时其所处的冰盖区域距离无冰南大洋的最短距离超过1000公里，浮标位置处观测到高度为8厘米的波浪信号。本研究利用欧洲中期天气预报中心（European Centre for Medium-Range Weather Forecasts, ECMWF）的再分析波浪数据，证实传入的波浪大概率为南大洋温带气旋（extratropical cyclone）催生的4米高海浪。此次事件中，波浪诱导的海冰破碎潜力可延伸至海冰区内数百公里范围。当Medusa-766在夏季驻留吕佐夫-霍尔姆湾期间，即便发生冰上波浪事件且海冰密集度较低，也未检测到显著的波浪能量。要阐明海浪对不稳定的吕佐夫-霍尔姆湾固定冰的影响，需先厘清波浪的衰减特性。Medusa-766的成功运行，证明了其整体设计的可靠性与所用传感器的高灵敏度，为未来吕佐夫-霍尔姆湾波浪-海冰相互作用研究奠定了良好基础。