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

气候变暖、冰川融化和海平面上升的概念已经深深植根于公众的意识中。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，可能每十年约0.5厘米。尽管如此，也确定了它们对海平面上升的贡献正在加速，可能每年上升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，由于大量的冰堆积在它们的盆地中，是阿蒙森区冰流；其中之一，松岛冰川，在过去的十年里已经损失了四倍。在过去的二十年里，我们通过连续的地球轨道卫星（ERS-1、ERS-2、ENVISAT、GRACE和最近的CryoSat-2）的测量，建立了对这些大冰盖行为的了解。同样，卫星的估计仍然不确定；这种不确定性是，随着人们对不断增加的捐款数额的关注增加，关闭它就变得越来越重要。本提案旨在针对阿蒙森区冰流直接解决这一问题。出现不确定性是因为卫星没有直接观测到冰盖的质量损失。有三种不同的仪器和技术，卫星测高、卫星重力和SAR干涉测量，每一种仪器和技术都包含一个更好的目标。卫星测高不能区分密度的变化和质量的变化。卫星重力测量无法区分由于冰的质量损失造成的变化和由于下面的固体地球运动造成的变化。SAR干涉测量依赖于不确定的斑块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和卫星测量来揭示，这些观测可以提供质量损失的完整图像。该提案旨在为阿蒙森扇区冰流提供这些“缺失”的测量数据，包括积雪、密度和固体地球运动，这些数据是在20年的卫星测量中获得的。在它的中心是松树岛冰川盆地在2012/3和2013/4年夏季的800公里横断面。两辆履带式车辆将载着科学家和他们的设备，沿着松岛冰川的支流前进。通过结合浅层和深层冰芯，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“雪”雷达的空中飞行来推断年代，年累积层及其在整个穿越过程中的密度。与此同时，从西南极洲的联合冰川起飞的另一个小组将从2012/3开始每年访问松树岛盆地以南罕见的地壳暴露（“nunataks”）。利用附在卫星上的自动GPD站，可以确定固体地球的运动。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积累、密度和固体地球运动模式的质量。有了这些资料，我们将能够确定历史（1992年以来）和正在进行的高度计、SAR和重力仪系列卫星的误差。其次，我们收集的数据（以及其他项目伙伴的数据）将用于更新这些模型。最后，我们将对整个南极西部冰原阿蒙森板块盆地对海平面的贡献及其随时间的趋势作出最佳估计。该结果还将与ISTAR-D“姊妹”项目的结果相结合，提供对这些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 behavior 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.