Drivers of Oceanic Change in the Amundsen Sea (DeCAdeS)

阿蒙森海海洋变化的驱动因素 (DeCAdeS)

• 批准号: NE/T012803/1
• 负责人: Adrian Jenkins
• 金额: $ 84.44万
• 依托单位: Northumbria University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT012803%2F1
• 关键词: Drivers; Oceanic; Change; Amundsen; Sea; Drivers; Oceanic; Change; Amundsen; Sea

Sea level rise is one of the most disruptive consequences of global warming, threatening coastal populations and infrastructure worldwide. If we are to develop strategies to either adapt to, or mitigate against, that threat, we need to know what to expect in the future. The biggest uncertainty in estimates of future sea level is the contribution of the vast Antarctic Ice Sheet. Observations of thinning in some parts of the ice sheet have led to suggestions that an irreversible change may already be underway that could add over a metre to sea level over the coming centuries.Thinning is most prominent in the Amundsen Sea sector of the ice sheet, where it has been observed to spread inland from the coast, and to affect neighbouring outflow glaciers in a similar way. Those facts demonstrate that some change in ocean-driven melting of the glacier termini has been the trigger of change, leading to a widespread belief that warming of the ocean waters, driven ultimately by global warming, is responsible. However, observations of ocean temperature in the Amundsen Sea suggest a more complex history. The records start in 1994, and include only a few observations prior to 2009, but suggest cycles between warm and cool conditions occurring over decadal periods. That motivates a major rethink of how the ocean interacts with the ice sheet to produce the observed thinning.In this project we plan to exploit new techniques to fill the gaps in the record of ocean temperature change in the Amundsen Sea. We will modify a robotic submarine so that it can over-winter beneath the pack ice, periodically measuring the properties and strength of the currents carrying warm water towards the ice. Those measurements will be complemented by fixed instruments that record continuously at selected locations and seal-borne sensors that will record the depth of the warm water wherever and whenever the seals dive below the surface to feed. We will relate these detailed observations of what is happening below the sea surface to changes in the height of the sea surface that can be detected by satellites. That will enable us to exploit the satellite records collected over three decades to infer past changes in the sub-surface ocean. The results will allow us to confirm the timing and magnitude of recent warm and cool cycles and relate them directly to the records of ice sheet thinning.To extend our knowledge of Amundsen Sea temperatures beyond the satellite era we will use a numerical model of the ocean circulation in the region to identify the patterns of atmospheric forcing that were responsible for the changes in temperature that we have observed. We will then examine reconstructions of the past atmospheric circulation to generate a history of the key atmospheric changes. Finally, we will investigate how those changes in the regional atmospheric circulation relate to global scale atmospheric change, providing us with the longer-term perspective that is needed to address the questions of what past conditions initiated the current thinning and what the future might hold.Should we find that the most recent decade is typical, and that earlier decades have been characterised by similar cycles in ocean forcing, we will have shown that predicting the future of the ice sheet requires an understanding of its response to extremes. Much like the coastal engineer planning for the impacts of climate change, who must construct sea defences to protect against the extreme levels generated when storm surges coincide with high tides, we need to understand how long and severe the warm extremes in the Amundsen need to be in order to trigger episodes of ice sheet thinning. We also need to know what combination of larger-scale modes of atmospheric variability produces the "perfect storm" in the Amundsen that can push the ice sheet out of balance. Our project will deliver the knowledge needed to address those critical questions.

海平面上升是全球全球变暖，威胁沿海人口和基础设施的最具破坏性后果之一。如果我们要制定策略以适应或减轻这种威胁，我们需要知道将来会发生什么。对未来海平面的估计，最大的不确定性是大量南极冰盖的贡献。在冰盖某些地区的某些地方的变化观察结果导致建议，可能已经进行了不可逆转的变化，在接下来的几个世纪中可能会增加一米米的海平面。在冰盖的阿蒙森海洋部门中，欺骗是最突出的，在冰盖的阿蒙森海洋部门中，已经观察到在海岸上散布在内陆，并影响邻近的邻近流出的冰川。这些事实表明，冰川末端的海洋驱动融化发生了一些变化，这是变化的触发因素，导致人们普遍认为，最终由全球变暖驱动的海水的变暖是负责的。但是，对阿蒙森海中海洋温度的观察表明，历史更为复杂。记录始于1994年，仅包括2009年之前的少量观察结果，但建议在十年期间发生的温暖和凉爽条件之间的周期。这激发了对海洋如何与冰盖相互作用以产生观察到的变薄的重大重新考虑。在这个项目中，我们计划利用新技术来填补阿蒙森海海洋温度变化的差距。我们将修改机器人潜艇，以便它可以在包装冰下过冬，并定期测量将温水朝冰的电流的特性和强度。这些测量值将由固定仪器进行补充，这些仪器在选定的位置和密封传感器中连续记录，这些传感器将在任何地方记录温水的深度，并且每当密封在地面以下潜水时，都会记录温水的深度。我们将将这些关于海面下方发生的事情的详细观察与卫星可以检测到的海面高度的变化有关。这将使我们能够利用三十年来收集的卫星记录来推断以下海洋的过去变化。结果将使我们能够确认最近的温暖和凉爽周期的时间和幅度，并将它们直接与冰盖的记录联系起来。为了扩展我们对Amundsen海温的了解，我们将使用该地区的海洋循环数字模型来确定大气强迫的模式，从而导致了我们已经观察到的温度变化。然后，我们将检查过去大气环流的重建，以产生关键大气变化的历史。最后，我们将调查区域大气循环中的这些变化如何与全球大气变化有关，为我们提供了长期的观点，需要解决过去的问题引发的问题的问题，以及我们最近的十年可能会发现什么是典型的。就像对气候变化的影响的沿海工程师计划一样，他们必须建立海上防御措施，以防止风暴潮流与高潮时产生的极端水平一样，我们需要了解阿蒙森（Amundsen）中需要多长时间和剧烈的极端情况才能触发冰片发作的发作。我们还需要知道大气变异性模式的组合会在Amundsen中产生“完美风暴”，从而将冰盖脱离平衡。我们的项目将提供解决这些关键问题所需的知识。