Bathymetry Beneath Ice Shelves of Western Dronning Maud Land, East Antarctica, and Implications on Ice Shelf Stability
Bathymetry Beneath Ice Shelves of Western Dronning Maud Land, East Antarctica, and Implications on Ice Shelf Stability
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DOI：
10.1029/2019gl086724
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发表时间：
2020-06-28
影响因子：
5.2
通讯作者：
Jokat, Wilfried
中科院分区：
文献类型：
--
作者：
Eisermann, Hannes;Eagles, Graeme;Jokat, Wilfried
南极洲的冰架在稳定为其提供水源的冰流方面发挥着关键作用。由于基底融化很大程度上取决于冰-海洋相互作用，因此获得一致的测深模型来估计冰架下的水和热交换至关重要。我们通过反演机载重力数据并结合地震、多波束和雷达深度参考，在 Dronning Maud Land 西部冰架下构建了测深模型。我们的模型揭示了冰架下方的深冰槽和靠近大陆架断裂处的终端冰碛，目前限制了来自南大洋的温暖深水的进入。冰架支撑着一个集水区，该集水区的冰体积相当于海平面上升近 1 m，部分容易受到海洋强迫的影响。水温和温跃层深度的变化可能会加速海洋冰盖的排水，并对未来全球海平面上升的贡献被低估。通俗易懂的语言摘要南极洲的接地冰盖由浮动冰架稳定。冰架质量的任何损失都会导致冰盖排水量的增加，从而导致海平面上升。 Dronning Maud Land 西部的冰架目前与内陆冰量保持平衡，有可能使全球海平面上升近 1 m。当温暖的海水从周围的海洋侵入时，冰架会失去其底部的大部分质量。这种情况发生的程度取决于冰架下方海底的深度和形状。我们使用机载重力数据以及地震、多波束和雷达数据的深度测量数据对 Dronning Maud Land 冰架下方的水深进行了建模。我们的测深模型显示了冰架下方的深槽和靠近大陆架的浅台。这些基台目前限制了与南大洋温暖深水的水体交换，从而保护冰架免受其底部的大幅融化。随着海洋温度升高或暖水团变浅而发生的气候变化可能会增加冰架融化并导致海平面上升。
Antarctica's ice shelves play a key role in stabilizing the ice streams that feed them. Since basal melting largely depends on ice-ocean interactions, it is vital to attain consistent bathymetry models to estimate water and heat exchange beneath ice shelves. We have constructed bathymetry models beneath the ice shelves of western Dronning Maud Land by inverting airborne gravity data and incorporating seismic, multibeam, and radar depth references. Our models reveal deep glacial troughs beneath the ice shelves and terminal moraines close to the continental shelf breaks, which currently limit the entry of Warm Deep Water from the Southern Ocean. The ice shelves buttress a catchment that comprises an ice volume equivalent to nearly 1 m of eustatic sea level rise, partly susceptible to ocean forcing. Changes in water temperature and thermocline depth may accelerate marine-based ice sheet drainage and constitute an underestimated contribution to future global sea level rise.Plain Language Summary The grounded ice sheets of Antarctica are stabilized by floating ice shelves. Any loss in ice shelf mass is matched by an increase in ice sheet drainage, which contributes to rising sea level. The ice shelves of western Dronning Maud Land are currently in balance with an inland ice volume that has the potential to raise global sea level by nearly 1 m. Ice shelves lose most of their mass from their bases when warm water intrudes from the surrounding ocean. The extent to which this occurs depends on the depth and shape of the seafloor beneath the ice shelves. We have modeled water depths beneath the ice shelves of Dronning Maud Land using airborne gravity data and depth measurements from seismic, multibeam, and radar data. Our bathymetric models show deep troughs beneath the ice shelves and shallow sills close to the continental shelf. These sills currently limit water mass exchange with Warm Deep Water from the Southern Ocean and so protect the ice shelves from significant melting at their bases. A changing climate with increasing ocean temperatures or a shallowing of warm water masses may increase ice shelf melting and lead to an increased sea level contribution.