Collaborative Research: Probing the Earth System in Patagonia: Crustal motion in relation to tectonics, earth structure, the hydrological cycle and climate change

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。在这项工作中，我们探讨了与气候引起的地表荷载变化有关的固体土的弹性和粘弹性响应。气候变化和相关负荷发生在不同的时间尺度上，从一个极端的年度水文循环到另一个极端的冰盖演变（过去2万年）。我们的地理重点是巴塔哥尼亚，它目前拥有南半球除南极洲以外最大的冰体。众所周知，巴塔哥尼亚冰原正在迅速消融，例如，按百分比计算，消融速度比阿拉斯加冰原更快，而且越来越多的证据表明，冰的消融正在加速。我们对这个地球系统科学项目的主要方法是通过地壳运动大地测量学和区域地球物理学，包括几种重叠现象的弹性和粘弹性建模。我们的研究任务之一是利用地球作为一个？体重秤吗?利用地球来衡量冰质量的年际变化？S对表面荷载变化的瞬时弹性响应。这种方法将通过将年度或季节性的负荷模式（原因）与相邻基岩的同期季节性振荡（效果）相关联来校准和验证。校准我们的？秤吗?通过这种方式，我们将能够非常迅速地探测和分析冰的长期增减速率的任何突然变化。我们将使用我们的结果来测试巴塔哥尼亚冰川后反弹（PGR）的所有预测。这里获得的结果也将提供必要的？PGR校正?利用重力恢复和气候实验（GRACE）卫星项目的重力数据向科学家提供校准信息，并使GRACE能够首次直接观测冰盖和海洋之间的质量传递。巴塔哥尼亚的结果也将为POLENET项目提供有用的投入。美国对气候变化影响的测量，这是一个具有巨大社会重要性的项目。人们普遍认为，南极西部或格陵兰岛的冰原存在严重的崩塌或破裂的危险，成为海洋中的冰山。这将在很短的时间内使海平面上升，比冰融化所需的时间要短得多，在此期间发生了这次破裂。与此相关的海平面上升将严重损害全球经济，并通过淹没全球大片人口密集的沿海地区，降低支持数亿人的社会基础设施。虽然在海平面上升成为严重问题之前扭转全球变暖可能为时已晚，但评估海平面上升可能造成的严重程度，以及政府应对或缓解它们可能无力阻止的事态发展的时间是至关重要的。该项目展示了固体地球科学对现代气候变化研究的贡献；它最广泛的影响可能是在全球范围内更好地测量冰盖和海洋之间的质量传递。在这项工作中，我们探讨了固体地球和气候之间的关系。这些地球过程包括构造、地下流变结构、弹性和粘弹性载荷响应。气候的贡献在时间尺度上有所不同，其中一个极端是年水文循环，另一个极端是全新世气候变化（最少）。我们的地理重点是巴塔哥尼亚，它拥有目前在南极洲以外的南半球发现的最大的冰体。这些冰体正在迅速消融，例如，按百分比计算，消融速度比阿拉斯加冰原还快，而且越来越多的证据表明，这种消融正在加速。我们对这个地球系统科学项目的主要方法是通过地壳运动大地测量（使用运动和连续GPS测量以及精确、科学的GPS处理工具）和区域地球物理，包括在时间和空间上重叠的各种物理现象的弹性和粘弹性建模。例如，我们研究中的一项任务是称重？冰质量的年际变化？S对表面荷载变化的瞬时弹性响应。这种方法将通过将年度或季节性的负荷模式（原因）与相邻基岩的同期季节性振荡（效果）相关联来校准和验证。校准我们的？秤吗?通过这种方式，我们将能够非常迅速地检测和分析可能发生的冰的长期增加或减少速率的任何突然变化。我们将利用我们的研究结果和所有关于冰川学的冰块振荡和长期趋势的可用信息来检验巴塔哥尼亚冰川后反弹（PGR）的所有可用预测。这里获得的结果也将提供必要的？PGR校正?为正确分析重力恢复与气候实验（GRACE）的重力数据提供校准信息。PGR校正将使GRACE能够第一次直接观测到冰盖和海洋之间的质量传递。与南极洲和格陵兰岛相比，在巴塔哥尼亚推行这一议程的好处包括：冰原的规模，那里已经记录的非常明显的构造梯度，更容易进入冰原周围的基岩，更便宜的物流，以及更密集和更容易管理的大地测量基础设施。巴塔哥尼亚的结果也将为POLENET项目提供有用的投入。美国对气候变化影响的测量，这对社会具有巨大的重要性。人们普遍认为，南极西部或格陵兰岛的冰原有崩塌的严重危险。这将严重损害全球经济，并使支持数亿人的社会基础设施退化，淹没世界各地人口密集的沿海地区的大片地区。虽然在海平面上升成为严重问题之前扭转全球变暖可能为时已晚，但评估海平面上升可能造成的严重程度，以及政府应对或缓解它们可能无力阻止的事态发展的时间是至关重要的。该项目展示了固体地球科学对现代气候变化研究的贡献；它最广泛的影响可能是在全球范围内更好地测量冰盖和海洋之间的质量传递。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).In this work we explore the elastic and viscoelastic responses of the solid earth related to climate induced surface load changes. The climate changes and associated loads occur at time scales ranging from annual hydrological cycles at one extreme to ice sheet evolution (over the past 20,000 years) at the other. Our geographical focus is Patagonia, which currently possesses the largest body of ice in the southern hemisphere outside of Antarctica. The Patagonian Ice Fields are known to be rapidly wasting, e.g. faster than those in Alaska in percentage terms, and there is growing evidence this ice loss is accelerating. Our primary approach to this earth system science project is through crustal motion geodesy and regional geophysics, including elastic and viscoelastic modeling of several overlapping phenomena. One task in our study is using the earth as a ?bathroom scale? to weigh annual and inter-annual changes in ice mass using Earth?s instantaneous elastic response to surface load changes. This approach will be calibrated and validated by relating annual or seasonal patterns of loading (the cause) with in-phase seasonal oscillations of adjacent bedrock (the effect). Having calibrated our ?weighing machine? in this way, we will be able to very quickly detect and analyze any abrupt changes in long term rates of ice gain or loss. We will use our results to test all predictions for postglacial rebound (PGR) in Patagonia. The results obtained here will also provide essential ?PGR correction? calibration information to scientists using gravity data from the Gravity Recovery and Climate Experiment (GRACE) satellite project, and enable GRACE to make the first direct observations of mass transfer between the ice sheets and the oceans. The results from Patagonia will also provide useful input to the POLENET project?s measurements of the effects of climate change, which is a project of tremendous societal importance. It is widely understood that there is serious danger that the W. Antarctic or Greenland ice sheets could collapse, or break up, and become icebergs in the ocean. This would raise sea level over the short time, much shorter than that necessary to melt the ice, during which this break up occurred. The rise in sea level associated with such a collapse would seriously damage the global economy and degrade the social infrastructure supporting hundreds of millions of people by inundating large swaths of densely inhabited coastal areas worldwide. While it may be too late to reverse global warming before sea level rise becomes seriously problematic, it is crucial to assess both the possible severity of sea level rise, and the amount of time that governments have to respond to, or mitigate developments they may be powerless to prevent. This project demonstrates the role in which solid earth sciences can contribute to modern climate change research; its broadest impact is likely to be a better metrology of mass transfer between ice sheets and the oceans at the global scale.In this work we explore relations between the solid earth and climate. These earth processes include tectonics, subsurface rheological structure, and elastic and viscoelastic loading responses. The climate contribution ranges over time scales encompassing annual hydrological cycles at one extreme to ice sheet evolution and Holocene climate change (at a minimum) at the other. Our geographical focus is Patagonia, which possesses the largest body of ice currently found in the southern hemisphere outside of Antarctica. These ice bodies are rapidly wasting, e.g. faster than the Alaskan ice fields in percentage terms, and there is growing evidence this ice loss is accelerating. Our primary approach to this earth system science project is through crustal motion geodesy (using both campaign and continuous GPS measurements and precise, scientific, GPS processing tools) and regional geophysics, including elastic and viscoelastic modeling of various physical phenomena overlapping in time and space. One task in our study for example is to ?weigh? annual and inter-annual changes in ice mass using Earth?s instantaneous elastic response to surface load changes. This approach will be calibrated and validated by relating annual or seasonal patterns of loading (the cause) with in-phase seasonal oscillations of adjacent bedrock (the effect). Having calibrated our ?weighing machine? in this way, we will be able to very quickly detect and analyze any abrupt changes in long term rates of ice gain or loss that may occur. We will use our results and all available information about ice mass oscillations and secular trends from glaciology to test all available predictions for postglacial rebound (PGR) in Patagonia. The results obtained here will also provide essential ?PGR correction? calibration information for proper analysis of gravity data from the Gravity Recovery and Climate Experiment (GRACE). The PGR correction will enable GRACE to make the first direct observations of mass transfer between the ice sheets and the oceans. The advantages of pursuing this agenda in Patagonia, over Antarctica and Greenland, include: the ?convenient? scale of the ice fields, the very pronounced tectonic gradients already documented there, the far easier access to bedrock surrounding the ice fields, the less expensive logistics, and a far denser and far more easily managed geodetic infrastructure. The results from Patagonia will also provide useful input to the POLENET project?s measurements of the effects of climate change, which is of tremendous societal importance. It is widely understood there is serious danger the W. Antarctic or Greenland ice sheets could collapse. This would seriously damage the global economy and degrade the social infrastructure supporting hundreds of millions of people by inundating large swaths of densely inhabited coastal areas worldwide. While it may be too late to reverse global warming before sea level rise becomes seriously problematic, it is crucial to assess both the possible severity of sea level rise, and the amount of time that governments have to respond to, or mitigate developments that they may be powerless to prevent. This project demonstrates the role in which solid earth sciences can contribute to modern climate change research; its broadest impact is likely to be a better metrology of mass transfer between ice sheets and the oceans at the global scale.