Networks of Sensors in Extreme Environments: High-Resolution Glacier Dynamic Monitoring

我们的工作汇集了科学和工程的两个重要领域：无线通信技术和冰川学。使用目前正在开发的无线通信创新技术来安装传感器网络，我们将增加对世界大冰盖将如何应对气候变化的理解，而在极端环境中试验无线网络所获得的知识将有助于开发下一代无线网络的工程师，如移动电话网络。格陵兰冰盖边缘周围是出口冰川，允许冰从冰盖中心流入大海。在冰与海相遇的地方形成冰山，离开冰盖的冰大约有一半是以这种方式形成的。这些冰川被认为对气温和海洋温度的变化非常敏感，但我们对它们的了解还不足以预测未来的变化，也不能理解已经观察到的变化。导致冰山形成(“崩解”)的过程特别重要，但人们对此知之甚少。特别是，迫切需要解决冰川流动的变化(‘动态’)如何与冰川末端位置和冰解率的变化相关联的问题。是其中一个驱动另一个，还是比这更复杂？为了理解这一点，我们需要知道格陵兰出口冰川崩解的主要机制是什么，我们需要以一致的、定量的方式描述所有这些冰川的这些机制。只有到那时，相关的过程才能在冰盖及其出口冰川的计算机模型中表现出来，使我们能够改进对它们将如何应对气候变化的预测。为了提高我们的了解，对冰山崩解事件进行详细的观测是至关重要的，但由于很难在裂缝严重的冰面上放置和维护仪器，因此很难获得这些观测结果。为了克服获得正确观测的问题，将在格陵兰东南部的一个重要的崩解冰川--赫尔海姆冰川上部署一个一次性GPS接收器网络。利用特殊的数据处理技术，GPS可以被用来进行精确到几厘米的测量。GPS接收器将相互连接，并通过可消耗性的低功率无线收发器网络连接到基站。网络的设计将意味着，如果部分数据丢失，仍可收集数据：它将自我修复。该网络及其组成部分的创新性使直升机在冰川崩解区部署大量传感器在经济上和后勤上成为可能。在该项目的生命周期内，我们预计将详细观察几个冰解事件。来自GPS接收器的数据将与来自飞机、卫星和立体摄影的其他数据来源相结合，以获得对冰山形成的前所未有的洞察。这些数据将与冰流的计算机模型相结合，使有关冰山形成的各种理论得以探索和测试。该项目的这一部分有可能在获得资助的工作结束后提供新的科学成果。

Our work brings together two important areas of science and engineering: wireless communications technology and glaciology. Using innovative techniques currently being developed for wireless communications to install a network of sensors, we will increase our understanding of how the world's large ice sheets will respond to climate change, while the knowledge gained by experimenting with wireless networks in an extreme environment will be of benefit to engineers developing the next generation of wireless networks such as mobile phone networks. Around the edge of the Greenland Ice Sheet are outlet glaciers, which allow ice to flow from the centre of the ice sheet into the sea. Where the ice meets the sea, icebergs are formed, and about half of the ice which leaves the ice sheet does so in this way. These glaciers are thought to be very sensitive to changes in air and ocean temperatures, but we do not yet know enough about them to be able to predict future changes, or understand those already observed. The processes leading to iceberg formation ('calving') are particularly important, but poorly understood. In particular, there is an urgent need to address the question of how changes in glacier flow ('dynamics') relate to changes in terminus position and calving rates. Does one drive the other, or is it more complex than that? To understand this, we need to know what the primary mechanisms are for calving in Greenland outlet glaciers, and we need characterise these mechanisms in a consistent, quantitative way across all such glaciers. Only then can the relevant processes be represented in computer models of the ice sheet and its outlet glaciers, allowing us to improve our predictions of how they will respond to climate change. To improve our understanding, it is vital to have detailed observations of iceberg calving events, but these are hard to obtain because of the difficulty of placing and maintaining instrumentation on the heavily-crevassed ice surface. To overcome the problem of getting the right observations, a network of expendable GPS receivers will be deployed on Helheim Glacier, an important calving glacier in south-east Greenland. Using special data processing techniques, GPS can be used to make measurements which are accurate to a few centimetres. The GPS receivers will be connected to each other and to a base station via a network of expendable, low-power wireless transceivers. The design of the network will mean that data can still be collected if parts of it are lost: it will be self-healing. The innovative nature of the network and its components make it economically and logistically possible to deploy a large number of sensors by helicopter in the calving region of the glacier. During the lifetime of the project, we expect to observe several calving events in detail. The data from the GPS receivers will be combined with other data sources, from aircraft, satellites and stereo photography, to obtain an unprecedented insight into iceberg formation. The data will be combined with computer models of ice flow, enabling various theories about iceberg formation to be explored and tested. This part of the project has the potential to deliver new science well beyond the end of the funded work.