Near-glacier surveying of a subglacial discharge plume: Implications for plume parameterizations
Near-glacier surveying of a subglacial discharge plume: Implications for plume parameterizations
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DOI：
10.1002/2017gl073602
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发表时间：
2017-07-16
影响因子：
5.2
通讯作者：
Stearns, L. A.
中科院分区：
文献类型：
--
作者：
Jackson, R. H.;Shroyer, E. L.;Stearns, L. A.
在南极冰川，羽流动力学影响海底融化、峡湾环流和融水的混合。模型通常依赖于浮力羽流理论来参数化羽流和海底融化;然而，由于缺乏近冰川测量，这些参数化在很大程度上未经测试。在这里，我们提出了一个高分辨率的海洋调查船舶和远程操作船附近的终点Kangerlussuup Sermia在格陵兰岛西部。这些新的观测揭示了近地表羽流的3-D结构和运输，起源于冰川末端的一个大型底切管道，这与轴对称羽流理论不一致，而轴对称羽流理论是海洋冰川模型中最常见的羽流表示。相反，观察表明，一个更广泛的上升流羽流“截断”线羽流类似于200米的宽度，具有较高的夹带和羽流驱动的熔体相比，典型的轴对称表示。我们的研究结果突出了冰下出口的几何形状在控制羽流动力学的重要性，与参数化的交换流和海底融化冰川峡湾模型的影响。
At tidewater glaciers, plume dynamics affect submarine melting, fjord circulation, and the mixing of meltwater. Models often rely on buoyant plume theory to parameterize plumes and submarine melting; however, these parameterizations are largely untested due to a dearth of near-glacier measurements. Here we present a high-resolution ocean survey by ship and remotely operated boat near the terminus of Kangerlussuup Sermia in west Greenland. These novel observations reveal the 3-D structure and transport of a near-surface plume, originating at a large undercut conduit in the glacier terminus, that is inconsistent with axisymmetric plume theory, the most common representation of plumes in ocean-glacier models. Instead, the observations suggest a wider upwelling plume-a "truncated" line plume of similar to 200 m width-with higher entrainment and plume-driven melt compared to the typical axisymmetric representation. Our results highlight the importance of a subglacial outlet's geometry in controlling plume dynamics, with implications for parameterizing the exchange flow and submarine melt in glacial fjord models.