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观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，但格陵兰和南极洲的巨大冰盖只贡献了一小部分，可能每十年约为0.5厘米。尽管如此，也可以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，这种加速在一定程度上是南极半岛变暖的结果，但更令人担忧的是阿蒙森冰川部门的冰流，因为它们的盆地中有大量的冰支持；松岛冰川是其中之一，其质量损失在过去十年中增加了四倍。我们对这些大冰盖的行为的了解是在过去20年里通过连续的地球轨道卫星：ERS-1、ERS-2、ENVISAT、GRACE和最近的CryoSat-2卫星的测量而确定的。同样，卫星的估计仍然不确定；这种不确定性是，随着人们对不断上升的贡献的规模的担忧加剧，关闭变得越来越重要。这项建议旨在直接针对阿蒙森冰流解决这一问题。由于卫星不能直接观测到冰盖的质量损失，所以出现了不确定性。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，每一种仪器和技术都包含一个贝叶斯黑度。卫星测高测量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引起的变化和由于底层固体地球运动造成的变化。合成孔径雷达干涉测量依赖于斑驳的表面测量和预报模型的不确定组合。这些不确定性只能通过其他地面观测来解开，这些观测与卫星测量一起，可以提供质量损失的完整图景。这项提议旨在为阿蒙森冰川段的冰流提供这些在20年的卫星测量中对积雪、密度和固体地球运动的“缺失”测量。冰流的核心是2012/3和2013/4南半球夏季的一条800公里长的松岛冰川盆地。两辆履带式车辆将载着科学家和他们的设备在松岛冰川支流周围行驶。通过沿导线的浅冰芯和深冰芯的组合，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’雷达的空中飞越，来推断整个导线的年代、年累积层及其密度。与此同时，从南极洲西部的联合冰川起飞的另一个考察队将从2012/3年度起每年访问松岛盆地南部罕见的地壳裸露(Nunatak)。使用连接到纽纳塔克的自动GPD站，可以确定固体地球的运动。这些观测将首先用于评估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。有了这些信息，我们将能够确定历史上(自1992年以来)和正在进行的一系列高度计、合成孔径雷达和重力仪卫星的误差。其次，我们收集的数据(以及项目合作伙伴的其他数据和其他数据)将用于更新这些模型。最后，我们将对整个西南极冰盖的阿蒙森扇区盆地对海平面的贡献及其随时间的趋势做出最佳估计。这一结果还将与ISTAR-D的“姊妹”计划的结果相结合，为这些大冰川盆地的未来提供最好的可用预测。

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.