iSTAR-D: The contribution to sea-level rise from the Amundsen Sea sector of Antarctica

气候变暖、冰层融化和海平面上升的概念在公众意识中根深蒂固。事实上，今天，虽然海平面以每十年约3厘米的速度上升，但格陵兰岛和南极洲的大冰盖只贡献了很小的一部分，也许每十年约0.5厘米。尽管如此，人们也确定，它们对海平面上升的贡献正在加速，每年可能高达0.1厘米。在南极洲，这种加速部分是由于南极半岛变暖的结果，但更令人担忧的是阿蒙森地区的冰流，因为在其盆地中有大量的冰;其中之一，松岛冰川，在过去十年中其质量损失增加了四倍。我们对这些大冰盖的行为的了解是在过去20年中通过一系列地球轨道卫星的测量而建立的：ERS-1、ERS-2、ENVISAT、GRACE和最近的CryoSat-2。同样，卫星估计数仍然不确定;随着人们对不断增加的贡献的规模越来越关注，消除这种不确定性越来越重要。该建议旨在直接针对阿蒙森扇形冰流解决这一问题，由于卫星没有直接观测冰盖的质量损失，因此产生了不确定性。有三种不同的仪器和技术，卫星测高，卫星重力测量和合成孔径雷达干涉测量，每一种都包含一个黑色的。卫星测高测量无法区分密度变化和质量变化。卫星重力测量无法区分这些变化是由于冰的质量损失造成的，还是由于下面的固体地球的运动造成的。合成孔径雷达干涉测量依赖于不确定的不完整表面测量和预测模型的组合。这些不确定性只能通过其他地面观测来解决，这些地面观测与卫星测量一起可以提供质量损失的完整图像。该方案旨在提供这些“缺失”的测量数据，包括20年来卫星测量的阿蒙森冰流的积雪、密度和固体地球运动。其核心是在2012/3和2013/4年的南半球夏季对松岛冰川盆地进行800公里的穿越。两辆履带式车辆，将在松岛冰川的支流周围前进，携带着科学家和他们的设备。通过结合浅层和深层的冰芯，沿着导线，我们将获得降雪及其密度的连续记录。我们将通过一个非常高分辨率的机载“雪”雷达来推断整个穿越过程中的年累积层及其密度。与此同时，从南极洲西部的联合冰川出发的另一个小组将从2012/3年起每年访问松岛盆地南部罕见的地壳（“冰原岛峰”）。使用自动GPD站连接到冰原岛峰，固体地球的运动可以确定。这些观测将首先用于评价目前与卫星数据一起使用的南极堆积、密度和固体地球运动模型的质量。有了这些资料，我们就能够确定历史上（从1992年起）和目前正在进行的一系列高度计、合成孔径雷达和重力计卫星的误差。其次，我们收集的数据（以及项目合作伙伴及其他合作伙伴的其他数据）将用于更新这些模型。最后，我们将产生对海平面的贡献的最佳估计，其在时间上的趋势，整个阿蒙森部门盆地的西南极冰盖。当与ISAR-D的“姐妹”计划的结果相结合时，其结果还将提供对这些巨大冰川盆地未来的最佳预测。

The notions of a warming climate, melting ice and rising sea levels are firmly rooted in the public consciousness. In fact, today, while sea level is rising at some 3 cm per decade, the great ice sheets of Greenland and Antarctica are only contributing a small component, perhaps some 0.5 cm per decade. Nonetheless, it is also established that their contribution to sea level rise is accelerating, by perhaps as much as 0.1 cm per year. In Antarctica, this acceleration is result, in part, of the warming Antarctic Peninsula, but of greater concern, because of the vast quantities of ice backed up in their basins, are the Amundsen sector ice streams; one of which, the Pine Island Glacier, has quadrupled its mass loss in the past decade. What we know about the behaviour of these large ice sheets has been established over the past two decades through measurements from successive Earth-orbiting satellites: ERS-1, ERS-2, ENVISAT, GRACE and most recently CryoSat-2. Equally, the satellite estimates remain uncertain; an uncertainty that, as concern increases as to the magnitude of the rising contribution, it is increasingly important to close down. This proposal aims to attack this problem directly for the Amundsen sector ice streams.The uncertainties arise because the satellites do not directly observe the mass loss of the ice sheets. There are three different instruments and techniques, satellite altimetry, satellite gravimetry, and SAR interferometry, and each of them contains a bete noir. Satellite altimetry measurements cannot distinguish changes in density from changes in mass. Satellite gravimetry cannot distinguish those changes due to mass loss from the ice from those due to the motion of the underlying solid Earth. SAR interferometry is reliant on an uncertain combination of patchy surface measurements and forecast models. These uncertainties can only be unraveled by other, ground observations that, together with the satellite measurements, can provide a complete picture of the mass loss. This proposal aims to provide these 'missing' measurements, of snow accumulation, of density, and solid Earth motion, over the two decades of the satellite measurements, for the Amundsen sector ice streams.At its heart is a 800 km traverse of the Pine Island glacier basin in the austral summers of 2012/3 and 2013/4. Two tracked vehicles, will progress around the tributaries of the Pine Island Glacier, carrying with them scientists and their equipment. Through a combination of shallow and deeper ice cores, along the traverse, we will obtain a continuous record of the snowfall and its density. We will extrapolate the dated, annual accumulation layers and their density throughout the traverse through an airborne over-flight of a very high resolution, 'snow' radar. In parallel, a separate party, flying out from Union Glacier in West Antarctica, will make annual visits from 2012/3 to rare exposures of the Earth's crust ('nunataks') south of the Pine Island Basin. Using automated GPD stations attached to the nunataks, the motion of the solid Earth can be determined. These observations will be used to, first, evaluate the quality of the models of Antarctic accumulation, density and solid Earth motion that are presently used with the satellite data. With this information, we will be able to determine the errors in the historical (from 1992) and on-going series of altimeter, SAR and gravimeter satellites. Second, the data we collect (and other data of Project Partners and beyond) will be used to update these models. Finally, we will generate the best estimate of the contribution to sea level, and its trend in time, throughout the Amundsen sector basins of the West Antarctic ice sheet. The result will also, when combined with the outcome of the 'sister' program of ISTAR-D, provide the best available prediction into the future of these great glacier basins.