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流失到海洋中。这是一个需要解决的重要问题，因为南极半岛的变暖速度比地球上任何其他地区都要快。尽管与大陆冰盖相比，南极半岛的冰川很小，但确定它们对海洋和大气温度上升的反应速度是至关重要的。这是至关重要的，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。测量有多少冰是困难的，而且取决于对体积和面积的准确估计。提高我们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。这种反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）连续监测。当然，地球基岩的运动不仅与即时反应有关，而且与反映长期消失的曾经覆盖整个南极半岛的冰块的长期速率有关。在最后一次冰期的时候。因此，这些反弹测量也可以告诉我们几千年前覆盖南极半岛的冰量。冰川均衡反弹是一个复杂的因素，使我们能够了解今天大冰原损失了多少，这可以通过卫星技术来估计，但只有在均衡（反弹）修正未知的情况下，误差才会很大。该研究建议在2016年之前保持六个反弹站，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站点，这些站点将专注于限制过去两年测量显示的反弹的“靶心”。此外，还将收集更多的地质数据点，这些数据点将有助于重建冰盖边缘从末次极大期的完整冰盖消退期间的位置。这些将以海洋沉积物序列的岩心为基础，这些沉积物序列现在被认为是沿着退缩的冰盖和出口边缘沉积的。对冰缘的精确测年以及新的和改进的反弹数据将有助于限制过去的冰盖结构，并改进与冰川后反弹性质相关的地球物理模型。数据管理将由联阿援助团极地地球物理网或POLENET主持，并将在台站安装时公开提供。该项目是正在进行的拉森冰架南极项目（LARISSA）的小规模延伸，该项目是国际极地年（IPY）资助的跨学科研究，旨在了解与拉森冰架和南极半岛北部有关的地球系统联系。