Calving rates at tidewater glaciers vary strongly with ocean temperature.
Calving rates at tidewater glaciers vary strongly with ocean temperature.
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DOI：
10.1038/ncomms9566
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发表时间：
2015-10-09
影响因子：
16.6
通讯作者：
Inall M
中科院分区：
文献类型：
--
作者：
Luckman A;Benn DI;Cottier F;Bevan S;Nilsen F;Inall M
潮水冰川崩解边缘的冰块质量损失率(正面消融率)是海平面上升预测中的一个关键不确定性。测量很困难，因为质量损失被不同速率的冰流所取代，而锋面消融包括空中崩解、海底融化和崩解。在这里，我们从异常密集的一系列卫星图像中计算出斯瓦尔巴群岛三个动态对比的冰川的正面消融率。我们结合海洋数据、冰锋位置和末端速度来研究对锋面消融的控制。我们发现锋面消融并不依赖于冰动力，也不受冰川表面冻结的影响，而是随次表层水温的强烈变化。我们得出的结论是，冰解是通过融化底切和冰锋崩塌进行的，这一过程可能主导着锋面消融，其中海底融化的速度可以超过冰流。我们的发现说明了建立潮水冰川对海洋强迫反应的简单模型的可能性。潮水冰川的崩解被认为依赖于冰的动力学，但缺乏直接的证据。这里，Luckman等人。使用卫星数据来计算动态对比斯瓦尔巴群岛冰川的正面消融率，并表明正面消融率主要随次表层海洋温度而变化。
Rates of ice mass loss at the calving margins of tidewater glaciers (frontal ablation rates) are a key uncertainty in sea level rise projections. Measurements are difficult because mass lost is replaced by ice flow at variable rates, and frontal ablation incorporates sub-aerial calving, and submarine melt and calving. Here we derive frontal ablation rates for three dynamically contrasting glaciers in Svalbard from an unusually dense series of satellite images. We combine ocean data, ice-front position and terminus velocity to investigate controls on frontal ablation. We find that frontal ablation is not dependent on ice dynamics, nor reduced by glacier surface freeze-up, but varies strongly with sub-surface water temperature. We conclude that calving proceeds by melt undercutting and ice-front collapse, a process that may dominate frontal ablation where submarine melt can outpace ice flow. Our findings illustrate the potential for deriving simple models of tidewater glacier response to oceanographic forcing. Tidewater glacier calving is assumed to be dependent on ice dynamics, but direct evidence is lacking. Here, Luckman et al. use satellite data to derive frontal ablation rates for dynamically contrasting Svalbard glaciers, and show that frontal ablation rate varies primarily with sub-surface ocean temperature.