Ocean Circulation and Ice Shelf Melting on the Amundsen Sea Continental Shelf

阿蒙森海大陆架上的海洋环流和冰架融化

基本信息

批准号：
NE/G001367/1
负责人：
Adrian Jenkins
金额：
$ 51.65万
依托单位：
British Antarctic Survey
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG001367%2F1
关键词：
Ocean Circulation Ice Shelf Melting

项目摘要

Sea levels around the world are currently rising by about 2 mm every year. That may not sound very much, but people living in areas such as Holland or East Anglia are already threatened by coastal erosion. If we are to say how that threat might change in the future we must learn how to forecast changes in sea level. To do this we must understand what is happening to the Earth's great reservoirs of freshwater, and whether or not they are slowly draining into the ocean. The largest of these reservoirs by far is the Antarctic Ice Sheet, which contains 70% of all the freshwater on the planet. At present we do not know whether the ice sheet is growing or shrinking overall, but we do know that some parts of it are getting smaller. The fastest changes are happening at the edge of the ice sheet, where it flows into the sea, in a place called Pine Island Bay. Nobody yet knows what is causing these changes, and their speed has taken scientists by surprise. Pine Island Bay is geographically the far south of the Pacific Ocean, and the image of warmth that this conjures up is not entirely misplaced. The air temperatures never rise above freezing and the coast is battered by storms, but beneath the cold surface of the sea, water temperatures rise as high as 1 degree Celcius. This may seem cold by our standards (sea temperatures around Britain rarely drop into single figures, even in winter), but it is warm enough to melt the ice. Pine Island Glacier is a vast river of ice that flows out into Pine Island Bay. It carries as much water as the River Rhine, but in frozen form. The last 75 km of the Glacier floats on the waters of Pine Island Bay, and the bottom melts so intensely that half of the ice carried in the glacier is lost within the space of 30 years. The other half breaks off the end of the glacier as icebergs, which drift away to melt elsewhere. It is not hard to understand that warm water causes rapid melting, but what do 'warm' and 'rapid' really mean? If we change the water temperature by a small amount, by how much will the melt rate change? To find the answers to those questions we must make measurements of the water temperature beneath the glacier, but to do so is enormously challenging. The glacier is between 300 m and 1 km thick, so we cannot get instruments through from above, while the drifting Antarctic pack ice bars access to the front of the glacier to all but the most powerful ships. Engineers working at the Southampton Oceanography Centre have, over many years, designed and built a solution to this problem in the form of a robotic submarine that they can programme to dive beneath the ice, make measurements along a pre-defined track, then return to the surface with the vital data. By teaming up with American scientists, who can make use of a powerful icebreaker, we hope to take the submarine right up to Pine Island Glacier and launch it on its mission beneath the ice.The underwater cavern beneath the glacier is completely unknown and the submarine must find its own way in and out, avoiding any obstacles that it finds along its path. The Antarctic pack ice is notoriously unpredictable and could prove a huge challenge to the ship. But the potential return makes the risks worthwhile. Armed with our new knowledge we will build a computer model that describes the flow of water within the remote cavern beneath the glacier and in the sea to the north of it. Using this model we will determine if there have been any changes in the water temperature in Pine Island Bay over the past 20 years and how such changes would have affected melting of the glacier base. Other scientists can then use our results to establish if changes in the glacier's melt rate could have caused the ice sheet to thin in the way that has been observed, and together we will be able to say with greater certainty what impact the glaciers of Pine Island Bay will have on the future coastlines of Holland and East Anglia.

目前，世界各地的海平面每年增加约2毫米。这听起来不太好，但是居住在荷兰或东英吉利等地区的人们已经受到沿海侵蚀的威胁。如果我们说将来这种威胁可能会发生变化，我们必须学习如何预测海平面变化。为此，我们必须了解地球上淡水的巨大水库正在发生的事情，以及它们是否正在慢慢排入海洋。到目前为止，这些水库中最大的是南极冰盖，该冰盖包含地球上所有淡水的70％。目前，我们不知道冰盖是否正在增长或整体缩小，但我们确实知道其中的某些部分越来越小。最快的变化正在冰盖的边缘发生，在冰盖的边缘，它流入了大海，在一个叫Pine Island Bay的地方。还没有人知道是什么原因导致了这些变化，他们的速度使科学家感到惊讶。派恩岛湾（Pine Island Bay）在地理位置上是太平洋南部的最南端，温暖的形象并没有完全放错地方。空气温度永远不会超过冰冻，海岸被暴风雨袭击，但是在海面的寒冷表面下，水温升高高达1度Celcius。根据我们的标准，这似乎很冷（英国周围的海温很少落入单一人物，即使在冬天，它也足够温暖，可以融化冰。派恩岛冰川是一条庞大的冰河，流入派恩岛湾。它的水与莱茵河一样多，但以冷冻形式含有。最后75公里的冰川漂浮在派恩岛湾的水域上，底部的融化如此强烈，以至于冰川中携带的一半冰在30年的时间内丢失了。另一半破裂了冰川的末端，因为冰山一片散发到其他地方融化。不难理解温水会导致快速融化，但是“温暖”和“快速”的意思是什么？如果我们将水温少量改变，熔体速率会改变多少？要找到这些问题的答案，我们必须对冰川下的水温进行测量，但是这样做非常具有挑战性。冰川厚度为300 m至1公里，因此我们无法从上方获得乐器，而漂流的南极包装冰条可以进入冰川前部，除了最强大的船只以外。多年来，在南安普敦海洋学中心工作的工程师已经以机器人潜艇的形式设计并建立了解决此问题的解决方案，他们可以编程以在冰下潜水，沿着预定的轨道进行测量，然后使用重要数据返回表面。通过与可以利用强大的破冰船的美国科学家合作，我们希望将潜艇直接带到Pine Island冰川并在冰下方的任务上启动。冰川下面的水下洞穴完全未知，潜艇必须找到自己的道路，避免在其路径上找到任何障碍。众所周知，南极背包冰是不可预测的，可能会对船只构成巨大挑战。但是潜在的回报使风险值得。凭借我们的新知识，我们将建立一个计算机模型，描述冰川下方和海洋北部的偏远洞穴中的水流。使用该模型，我们将确定过去20年中松岛湾的水温发生了任何变化，以及这种变化如何影响冰川基座的熔化。然后，其他科学家可以利用我们的结果来确定冰川熔体速率的变化是否可能导致冰盖的观察方式变薄，并且我们将能够更确定地说，派恩岛湾冰川对霍兰德和东安格利亚的未来海岸线的影响会产生什么影响。