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

TL;DR

This study reports the successful deployment of a wave-ice buoy in Antarctica that detected ocean wave signals over 1,000 km into winter pack ice, revealing wave propagation and potential ice breakup influences.

Contribution

It introduces a robust drifting wave-ice buoy, Medusa-766, capable of long-term operation in Antarctic winter conditions and provides new insights into wave propagation into sea ice.

Findings

Waves generated by extratropical cyclones can propagate over 1,000 km into Antarctic winter ice.

Wave signals were detected deep within the ice cover during winter, indicating significant wave penetration.

Wave-induced ice breakup potential extends hundreds of kilometers into the ice field.

Abstract

A drifting wave-ice buoy, which was configured by mounting the OpenMetBuoy on an ad hoc floating platform that we named Medusa, was deployed at the L\"utzow-Holm Bay (LHB) marginal ice zone in Antarctica on 4 Feb 2022 during the 63rd Japanese Antarctica research expedition. The wave-ice buoy, Medusa-766, survived the Antarctica winter as the measurement duration reached 333 days. During the winter months, 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 ocean wave signals at the buoy position. Using the directional wave spectra obtained from the ECMWF's reanalysis, we show that the Medusa-766 observed waves were likely generated by an extratropical cyclone in the Southern Ocean. Wave-induced ice breakup potential for such an event could extend 100s km into the ice field. When Medusa-766 was in LHB in the summer months, it did not detect sizeable wave energy despite the low sea ice concentration extent even during on-ice waves events. Characterising the considerable differences in the wave attenuation at LHB is needed to elucidate the relative contribution of ocean waves to the unstable LHB fast ice. The success of Medusa-766 demonstrates the robustness of the general design, hardware, firmware, and the high sensitivity of the sensor used. The result is promising for future LHB wave-ice interaction research.