Coupled Evolution of Ice Shelf and Ocean in the Amundsen Sea Sector of Antarctica

南极阿蒙森海区冰架与海洋的耦合演化

• 批准号: NE/Y000811/1
• 负责人: Pierre Dutrieux
• 金额: $ 54.73万
• 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: 2026
• 资助国家: 英国
• 起止时间: 2026 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY000811%2F1
• 关键词: Coupled; Evolution; Ice; Shelf; Ocean

As our planet warms the ice cover shrinks, a process that transfers water from land to ocean and thereby raises sea level. The result, which could ultimately raise global sea level by 10s of metres, seems intuitively obvious. However, in the case of the Antarctic Ice Sheet, the processes at work are less than obvious. The atmosphere over the ice sheet is too cold to drive significant melting, so all the snow that falls in the interior is returned to the ocean as ice that only melts once it is afloat. The cold atmosphere creates cold surface waters, so most of the heat that melts the ice comes from deep within the ocean's interior. As it melts the floating ice from underneath, the thinning of the so-called ice shelves allows ice to flow off the land more rapidly, hence raising sea level.So, the underlying process is clear, but why should it drive a loss of ice from Antarctica as the climate warms? The waters that melt the ice are too deep in the ocean to feel atmospheric warming. However, as the atmosphere warms the circulation patterns change, influencing the winds that drive the ocean currents, and that delivers more of the deep warm water to the ice. Understanding how the processes work has been challenging. It is not immediately obvious why a change in the winds should deliver more, rather than less, warm water to the ice. Nevertheless, observation and modelling give us a consistent answer and our understanding of the processes grows as we focus our research on key unknowns.However, there is another puzzle that has received much less attention to date. More warm water leads to more rapid melting of the ice shelves, they thin and the flow of ice off the land accelerates. That acceleration of the flow delivers more ice to the ice shelves, and they should therefore start to grow, or at least thin less rapidly, unless the ocean heat delivery continues to grow. Until recently it was assumed that that is exactly what was happening, but as our record of ocean observations has lengthened, we have seen decadal cycles of warming and cooling. Why then should the ice shelves continue to thin?The answer must lie in the way in which the thinning of the ice shelves themselves affects the melt rate. Again, it is not immediately clear why the change in the ice should increase rather than decrease the melt. However, in this case observation of the key processes is exceptionally difficult because they take place beneath 100s or even 1000s of metres of ice.That is the challenge we will address with this project, by sending an autonomous submarine beneath the ice to make the critical measurements of the ocean, including the temperature of the water and the currents. Those direct observations of the ocean beneath the ice will allow us to verify that the ocean models we use to simulate the processes are correct, or to improve them if they are not.This will not be the first time such measurements have been made, but the new observations will differ in two important respects from the very few that have been made in the past. Some will be repeats of earlier measurements, so we will have observations from before and after a significant change in the extent of the ice shelf. Thus, we can directly answer the question of what change in the ocean circulation accompanied the change in shape of the ice cover. Other observations will target regions where the ice was grounded until recently. Because radar signals penetrate ice, but not seawater, we are able to map the topography only when the ice rests on the land and not when it is afloat. Thus, we paradoxically know the geometry of newly formed ocean cavities with much greater accuracy than we do the cavities that have been there since humans first explored the south polar regions. Our ability to understand the links between cavity geometry and ocean circulation is therefore enhanced in the newly opened cavities that are among the targets of our field campaign.

随着我们的星球温暖冰盖的缩小，这种过程将水从陆地转移到海洋，从而提高了海平面。结果最终可能会使全球海平面提高10米，这在直觉上似乎很明显。但是，在南极冰盖的情况下，工作过程并不明显。冰盖上的气氛太冷，无法驱动大量的熔化，因此，落在内部的所有雪都被返回到海洋中，因为冰只能融化，一旦融化。寒冷的大气会产生冷水域，因此融化冰的大部分热量来自海洋内部的深处。当它从下面融化漂浮的冰时，所谓的冰架的稀疏使冰可以更快地从土地上流出，从而提高了海平面。融化冰的水在海洋中太深，无法感受到大气变暖。但是，随着大气变暖，循环模式发生了变化，影响了驱动洋流的风，并将更多的深水水输送到冰上。了解该过程的工作方式一直是具有挑战性的。为什么风中的变化应该更多而不是更少的温水。然而，观察和建模为我们提供了一致的答案，并且随着我们将研究集中在关键未知的过程中，我们对过程的理解也会增长。更温水会导致冰架的更快融化，它们稀薄，而冰上的流动会加速。流动的加速度会给冰架带来更多的冰，因此，除非海热递送不断增长，否则它们应该开始生长，或者至少较小。直到最近，人们认为这正是正在发生的事情，但是随着我们海洋观测记录的延长，我们已经看到了变暖和冷却的十年周期。那么为什么冰架子继续稀疏？答案必须在于冰架本身会影响熔体速率的方式。同样，尚不清楚为什么冰的变化应该增加而不是减少熔体。但是，在这种情况下，对关键过程的观察非常困难，因为它们发生在100秒甚至1000米的冰中。这是我们将在该项目中应对的挑战，它是通过在冰下发送自主潜水艇来使海洋的关键测量值，包括水和潮流的温度。那些直接观察到冰下的海洋将使我们能够验证我们用来模拟过程的海洋模型是否正确，或者如果不正确，则可以改进它们。这不是第一次进行此类测量，但新观察结果与过去几乎没有的两个重要界面会有所不同。有些将是早期测量值的重复，因此我们将对冰架范围的显着变化进行观察。因此，我们可以直接回答一个问题，即海洋循环中发生了什么变化，伴随着冰盖的形状变化。其他观察结果将针对直到最近才能扎根的区域。由于雷达信号渗透冰，但没有海水，因此我们只有在冰放在陆地上而不是浮动时才能绘制地形。因此，与我们在人类首次探索南极区域以来一直在那里的空腔相比，我们矛盾地知道新形成的海洋腔的几何形状，其准确性要大得多。因此，在我们现场运动的目标之一的新开放的腔体中，我们了解了了解腔几何形状与海洋循环之间联系的能力。