Internal Gravity Waves Generated by Subglacial Discharge: Implications for Tidewater Glacier Melt

Submarine melting has been implicated in the accelerated retreat of marine-terminating glaciers globally. Energetic ocean flows, such as subglacial discharge plumes, are known to enhance submarine melting in their immediate vicinity. Using observations and a large eddy simulation, we demonstrate that discharge plumes emit high-frequency internal gravity waves that propagate along glacier termini and transfer energy to distant regions of the terminus. Our analysis of wave characteristics and their correlation with subglacial discharge forcing suggest that they derive their energy from turbulent motions within the discharge plume and its surface outflow. Accounting for the near-terminus velocities associated with these waves increases predicted melt rates by up to 70%. This may help to explain known discrepancies between observed melt rates and theoretical predictions. Because the dynamical ingredients-a buoyant plume rising through a stratified ocean-are common to many tidewater glacier systems, such internal waves are likely to be widespread.

海底熔化与全球海洋终止冰川的加速撤退有关。已知能量的海洋流量，例如冰山下排放羽流，可以增强其附近的海底融化。使用观测值和大型涡流模拟，我们证明了排放羽流散发出高频内重力波，该重力波沿着冰川末端传播并将能量转移到末端的遥远区域。我们对波特征的分析及其与亚冰分排放强迫的相关性表明，它们从排放羽流中的湍流及其表面流出中得出了能量。与这些波浪相关的近端速度的核算增加了预测的熔体速率高达70％。这可能有助于解释观察到的熔体速率和理论预测之间的已知差异。由于动态成分 - 通过许多潮水冰川系统共有的分层海洋升起的浮羽，因此这种内部波很可能很普遍。