Autonomous underwater vehicle (AUV) observations of recent tidewater glacier retreat, western Svalbard
Autonomous underwater vehicle (AUV) observations of recent tidewater glacier retreat, western Svalbard
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DOI：
10.1016/j.margeo.2019.106009
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发表时间：
2019-11-01
期刊：
影响因子：
2.9
通讯作者：
Verchili, David
中科院分区：
文献类型：
--
作者：
Howe, John A.;Husum, Katrine;Verchili, David
最近的研究突出表明，我们需要更好地了解冰川前沿水深测量与海洋学之间的关系，以便更好地预测冰川的动态。斯瓦尔巴群岛西部的冰海峡湾受到西斯匹次卑尔根海流平流的温带大西洋水的强烈影响。海洋终止冰川通过沉积物、营养物和淡水的流动对许多斯瓦尔巴特峡湾产生局部影响，但它们对海洋变暖的反应以及它们最近在海底退缩留下的印记仍然没有得到解决。在这里，我们提出了一个自主水下航行器（AUV）从四个冰川冰川收集的冰川前缘数据; Fjortende Julibreen（Krossfjorden），Conwaybreen，Kongsbreen和Kronebreen（Kongsfjorden）。冰川终点附近的海床已绘制成图，提供了高分辨率水深测量（0.5米至1.0米网格大小）、侧扫和照片，并同时进行了其他海洋学观测。目的是调查冰川前缘海底地貌，确定水团结构，并观察任何融水羽流活动。测深数据显示了多种多样的冰川地貌组合，包括众多的退缩冰碛、冰川线理、决口挤压脊和沉积物碎屑流，反映了冰川前缘的动态沉积环境。这些特征的年龄和每年的退缩速度是使用卫星遥感图像来估计的，以数字化冰川前缘随时间的位置。冰川地貌是由过去几年的退缩造成的，因为这些冰川逐渐成为陆地的终结。自主式潜水器还在两个最活跃的冰川（Kongsbreen和Kronebreen）现场观测到冰下融水羽流，并在冰川表面观测到温暖的大西洋水的相关特征。相对温暖的海洋沃茨的存在增强了次表层融化，加速了消融速率，而淡水（融化）注入深度影响当地水团结构和更广泛的峡湾环流。在Kongsbreen和Kronebreen的冰川前沿，冰下融水羽流的沉积作用占主导地位的冰近端区，悬浮液的沉积作用在远离冰川的地方更为普遍。这项研究显示了动态冰川海洋系统对当地海洋环境变化的敏感性，以及自动驾驶车辆的使用如何通过收集同时高分辨率的原位数据集来极大地帮助监测冰川变化，其中缺乏基于船舶的观测。
Recent studies have highlighted the need to improve our understanding of the relationship between glacial-front bathymetry and oceanography in order to better predict the behaviour of tidewater glaciers. The glaciomarine fjords of western Svalbard are strongly influenced by temperate Atlantic Water advected from the West Spitsbergen Current. Marine terminating (tidewater) glaciers locally influence many Svalbard fjords through fluxes of sediments, nutrients and freshwater, however their response to ocean warming and the imprint left by their recent retreat on the seabed remains unresolved. Here we present glacial front data collected by an autonomous underwater vehicle (AUV) from four tidewater glaciers; Fjortende Julibreen (Krossfjorden), Conwaybreen, Kongsbreen and Kronebreen (Kongsfjorden). The seabed adjacent to the glacial terminus has been mapped providing high-resolution bathymetry (0.5 m-1.0 m grid cell size), side-scan and photographs with additional simultaneous oceanographic observations. The aim being to survey the glacial front submarine landforms, to identify the water mass structure and to observe any melt water plume activity. The bathymetry data displays a diverse assemblage of glacial landforms including numerous retreat moraines, glacial lineations, crevasse-squeeze ridges and sediment debris flows reflecting the dynamic depositional environment of the glacial front. The age of the features and the annual rate of retreat have been estimated using satellite remote sensing imagery to digitise the glacial front positions over time. The glacial landforms have been produced by the last few years of retreat as these glaciers gradually become land-terminating. The AUV also observed in-situ subglacial meltwater plumes at the two most active glaciers (Kongsbreen and Kronebreen) and an associated signature of warm Atlantic Water occurring at the glacier face. The presence of relatively warm, oceanic waters enhances subsurface melting, accelerating the ablation rate, while fresh (melt) water injection at depth influences local water mass structure and the wider fjord circulation. At the glacial fronts of Kongsbreen and Kronebreen sedimentation from subglacial meltwater plumes dominate the ice-proximal zone and settling from suspension is more prevalent away from the glacier. This study shows how sensitive dynamic glaciomarine systems are to change in the local marine environment and how the use of autonomous vehicles can greatly aid in the monitoring of glacial change by collecting simultaneous high-resolution in-situ datasets where vessel based observations are lacking.