Continuation of the LARISSA Continuous GPS Network in View of Observed Dynamic Response to Antarctic Peninsula Ice Mass Balance and Required Geologic Constraints

鉴于观测到的对南极半岛冰块平衡的动态响应和所需的地质限制，LARISSA 连续 GPS 网络的延续

• 批准号: 1433140
• 负责人: Eugene Domack
• 金额: $ 3.75万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1433140&HistoricalAwards=false
• 关键词: Continuation; LARISSA; Continuous; GPS; Network

This project aims to identify which portions of the glacial cover in the Antarctic Peninsula are losing mass to the ocean. This is an important issue to resolve because the Antarctic Peninsula is warming at a faster rate than any other region across the earth. Even though glaciers across the Antarctic Peninsula are small, compared to the continental ice sheet, defining how rapidly they respond to both ocean and atmospheric temperature rise is critical. It is critical because it informs us about the exact mechanisms which regulate ice flow and melting into the ocean. For instance, after the break- up of the Larsen Ice Shelf in 2002 many glaciers began to flow rapidly into the sea. Measuring how much ice was involved is difficult and depends upon accurate estimates of volume and area. One way to increase the accuracy of our estimates is to measure how fast the Earth's crust is rebounding or bouncing back, after the ice has been removed. This rebound effect can be measured with very precise techniques using instruments locked into ice free bedrock surrounding the area of interest. These instruments are monitored by a set of positioning satellites (the Global Positioning System or GPS) in a continuous fashion. Of course the movement of the Earth's bedrock relates not only to the immediate response but also the longer term rate that reflects the long vanished ice masses that once covered the entire Antarctic Peninsula?at the time of the last glaciation. These rebound measurements can, therefore, also tell us about the amount of ice which covered the Antarctic Peninsula thousands of years ago. Glacial isostatic rebound is one of the complicating factors in allowing us to understand how much the larger ice sheets are losing today, something that can be estimated by satellite techniques but only within large errors when the isostatic (rebound) correction is unknown.The research proposed consists of maintaining a set of six rebound stations until the year 2016, allowing for a longer time series and thus more accurate estimates of immediate elastic and longer term rebound effects. It also involves the establishment of two additional GPS stations that will focus on constraining the "bull's eye" of rebound suggested by measurements over the past two years. In addition, several more geologic data points will be collected that will help to reconstruct the position of the ice sheet margin during its recession from the full ice sheet of the last glacial maximum. These will be based upon the coring of marine sediment sequences now recognized to have been deposited along the margins of retreating ice sheets and outlets. Precise dating of the ice margin along with the new and improved rebound data will help to constrain past ice sheet configurations and refine geophysical models related to the nature of post glacial rebound. Data management will be under the auspices of the UNAVCO polar geophysical network or POLENET and will be publically available at the time of station installation. This project is a small scale extension of the ongoing LARsen Ice Shelf, Antarctica Project (LARISSA), an IPY (International Polar Year)-funded interdisciplinary study aimed at understanding earth system connections related to the Larsen Ice Shelf and the northern Antarctic Peninsula.

该项目旨在确定南极半岛冰川覆盖的哪些部分正在向海洋流失。这是一个需要解决的重要问题，因为南极半岛变暖的速度比地球上任何其他地区都快。尽管南极半岛的冰川与大陆冰盖相比很小，但确定它们对海洋和大气温度上升的反应速度至关重要。它很重要，因为它告诉我们调节冰流和融化到海洋的确切机制。例如，2002年拉森冰架破裂后，许多冰川开始迅速流入大海。测量涉及的冰量很困难，并且取决于对体积和面积的准确估计。提高估计准确性的一种方法是测量冰被移除后地壳反弹或反弹的速度。这种回弹效应可以通过非常精确的技术来测量，使用锁定在感兴趣区域周围的无冰基岩中的仪器。这些仪器由一组定位卫星（全球定位系统或 GPS）持续监控。当然，地球基岩的运动不仅与即时反应有关，还与长期速率有关，该速率反映了在上次冰川作用时曾经覆盖整个南极半岛的长期消失的冰块。因此，这些回弹测量还可以告诉我们数千年前覆盖南极半岛的冰量。冰川均衡回弹是让我们了解当今较大冰盖损失量的复杂因素之一，这可以通过卫星技术进行估计，但在均衡（回弹）校正未知时只能在较大误差范围内。该研究提出包括维持一组六个反弹站直到 2016 年，允许更长的时间序列，从而更准确地估计即时弹性和长期反弹效应。它还涉及建立两个额外的 GPS 站，重点是限制过去两年测量结果显示的反弹“靶心”。此外，还将收集更多的地质数据点，这将有助于根据末次盛冰期的完整冰盖重建冰盖边缘在衰退期间的位置。这些将基于海洋沉积物序列的取芯，这些沉积物序列现已被认为是沿着消退的冰盖和出口边缘沉积的。冰缘的精确测年以及新的和改进的回弹数据将有助于限制过去的冰盖构造并完善与冰河后回弹性质相关的地球物理模型。数据管理将在 UNAVCO 极地地球物理网络或 POLENET 的支持下进行，并将在站安装时向公众开放。该项目是正在进行的南极洲拉森冰架项目 (LARISSA) 的小规模延伸，这是一项由 IPY（国际极地年）资助的跨学科研究，旨在了解与拉森冰架和南极半岛北部相关的地球系统联系。