Airborne geophysical investigation targets basal boundary conditions for the Institute and Moller ice streams, West Antarctica

该研究所和莫勒冰流(IIS/MIS)向罗恩冰架排放了大约20%的西南极冰盖(WAIS)，但与西南极其他快速流动的地区相比，我们对它们当前的形态和流动历史的了解受到了严格的限制。有关冰层厚度和冰盖床的数据仅限于1970年代获得的调查断面。Bingham和Siegert(2007)检查了这些数据，发现非常平滑和平坦的海床类似于流入罗斯冰架的西普尔海岸冰流。由于六海岸地区被认为是在冰盖比今天小的时候沉积的海洋沉积物，Bingham和Siegert(2007)得出了研究所/莫勒地区类似的、可能同时发生的历史结论。这一发现对南极洲西部未来的变化具有重要意义。Bingham和Siegert(2007)的分析使我们能够假设西南极三个主要排水口中的两个有大量以前的冰架流失和接地线撤退。因此，显然有必要对研究所和莫勒冰流进行广泛的航空地球物理调查，以检验这一假设并更好地了解未来变化的风险。调查还将使我们能够更好地描述西南极的海底地形和地质边界条件，这将使我们能够通过数值模拟更好地量化整个WAIS的流量和形态。该项目的目标如下。1.对研究所和西南极洲的莫勒冰流进行航空地球物理调查。2.利用雷达资料定量计算河床地形和测量河床粗糙度。3.绘制地层结构图(层状和裂隙)。4.确定动力反射系数，形成对基本水量分布的评价。5.分析磁力和重力异常，得出冰流的地质边界条件。6.利用数值模拟对现代和古代冰流过程进行量化。7.使用数值模拟来预测以前的变化再次发生的风险。该项目将产生以下成果：1.对迄今鲜为人知的西南极地区的冰下地形(和河床粗糙度)进行量化。这些信息将提供给BEDMAP II数据库，并将作为模拟边界条件的冰盖作出基本贡献。我们将对这些数据进行分析，以确定景观演变和冰盖历史。2.冰下热条件的划分和冰下湖泊的位置。这将使我们能够理解冰川流动和冰下湖泊/水文演变是如何相互关联的，并受到冰下地质和热条件的影响。3.广域信息系统中海绵结构的测量。我们将分析这些信息，以计算冰盖的流动历史，并勾勒出现在和最近过去IIS和MIS的边缘。4.WAIS的IIS和MIS集水区的地壳结构和冰下地质的定义。WAIS的冰川历史与对当今崩塌和海平面上升风险的评估有直接关系。我们的目标是通过与南极研究科学委员会题为南极气候演变(ACE)的科学研究方案链接，直接向国际科学界报告我们的成果，该方案综合了地质学和地球物理学的数据集，形成了关于过去变化的假设，可以通过建模进行检验。ACE链接还允许我们通过SCAR在该组织中的观察员身份向IPCC传播结果。我们还将向名为冰下南极湖泊环境(SALE)的SCAR方案提供结果，并将向国际南极数字磁异常项目贡献新的磁力数据集。

The Institute and Möller ice streams (IIS/MIS) drain about 20% of the West Antarctic Ice Sheet (WAIS) to the Ronne Ice Shelf, yet our knowledge of their current form and flow history is severely restricted compared with other fast flowing regions in West Antarctica. Data relating to the ice thickness and the ice-sheet bed is limited to reconnaissance transects acquired in the 1970s. Bingham and Siegert (2007) inspected these data, and showed the remarkably smooth and flat bed was similar to the Siple Coast ice streams that drain to the Ross Ice Shelf. As the Siple Coast region is thought to be underlain by marine sediments, deposited when the ice sheet size was smaller than today, Bingham and Siegert (2007) concluded a similar, probably simultaneous, history for the Institute/Möller region. The implications of this finding are significant for future changes in West Antarctica. Bingham and Siegert's (2007) analysis allows us to hypothesise substantial former ice-shelf loss and grounding line retreat in two of the three major drainage outlets of West Antarctica. An extensive airborne geophysical survey of the Institute and Möller ice streams is therefore clearly warranted, to test this hypothesis and better understand the risk of future change. The survey will also allow a better depiction of bed topography and geological boundary conditions in West Antarctica, which will allow us to better quantify the flow and form of the entire WAIS through numerical modelling. The project's objectives are as follows. 1. To undertake an airborne geophysical survey of the Institute and Möller ice streams of West Antarctica. 2. To quantify bed topography and measure bed roughness from radar data. 3. To map englacial structures (layering and crevasses). 4. To determine power reflection coefficients, forming an appreciation of basal water distribution. 5. To analyse magnetic and gravity anomalies to derive geological boundary conditions for ice flow. 6. To employ numerical modelling to quantify modern and ancient ice flow processes. 7. To use numerical modelling to predict the risk of former changes reoccurring. This project will result in the following deliverables: 1. The quantification of subglacial topography (and bed roughness) in a hitherto poorly known region of West Antarctica. This information will be made available to the BEDMAP II database, and will make a fundamental contribution as an ice sheet modelling boundary condition. We will analyse these data to determine landscape evolution and ice sheet history. 2. The classification of subglacial thermal conditions and locations of subglacial lakes. This will allow us to comprehend how ice stream flow and subglacial lake/hydrology evolution is both interrelated and affected by subglacial geology and thermal conditions. 3. The measurement of the englacial structure in the WAIS. We will analyse this information to calculate the flow history of the ice sheet and to delineate the margins of the IIS and MIS both now and in the recent past. 4. The definition of crustal structure and subglacial geology of the IIS and MIS catchments of the WAIS. The glacial history of the WAIS is of direct relevance to assessments of the present day risk of collapse and sea level rise. We aim to report our results directly to the international scientific community by linking to the Scientific Committee on Antarctic Research's (SCAR) scientific research programme entitled Antarctic Climate Evolution (ACE), which integrates geology and geophy sical datasets, forming hypotheses concerning past changes, which can be tested through modelling. The ACE link also allows us to disseminate results to the IPCC through SCAR's observer status in that organisation. We will also make results available to the SCAR programme named Subglacial Antarctic Lake Environments (SALE) and will contribute the new magnetic dataset to the international Antarctic Digital Magnetic Anomaly Project.