Collaborative Research: Polarimetric Characteristics of Radio-wave Scattering from Water Pathways within glaciers: Laboratory Experiments and Computer Simulations

合作研究：冰川内水路无线电波散射的偏振特性：实验室实验和计算机模拟

• 批准号: 0520465
• 负责人: Hans-Peter Marshall
• 金额: $ 6.98万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0520465&HistoricalAwards=false
• 关键词: Collaborative; Research; Polarimetric; Characteristics; Radio

ABSTRACTMarshallOPP-0520541MatsuokaOPP0520465Intellectual Merits: This is a collaborative proposal by Principal Investigators from the Universities of Washington and Colorado. Water pathways within glaciers transport melt water from the glacier surface to the glacier bed. Water lubricates the bed and introduces significant seasonal and daily variations in ice velocity in mountain glaciers. Current polar ice sheets encounter minor surface melting, but ongoing warming in coastal regions of the ice sheets may change this. If water can get to the bed, significant acceleration of ice flow may occur, which has recently been observed in Greenland. This could ultimately result in rapid fresh-water discharge in the Arctic, significantly contributing to global sea-level rise. Mapping water pathways and their temporal changes is crucial for understanding the spatial and temporal lags between surface melting and bed lubrication events and, more generally, glacier hydrology and mechanics. Remote sensing with ice-penetrating radar is a viable way to investigate temporal and spatial variations of the ice interior. Radar studies can potentially reveal much more than simply the geometry of the bedrock and internal layers. The Principal Investigators will carry out laboratory experiments and computer simulations to investigate how shape, slope, azimuth, dimensions, and contents (air or water) of scatterers within glaciers alter radio-echo intensities as a function of radar frequency and polarization. They will measure scattering from boreholes within an ice cube in a cold room and from thermoplastic polymers that are hanged within an open space. The latter gives an analog of water-filled scatter in glaciers. In each experimental venue, they will examine the bulk scattering from multiple inclusions for various azimuths of the radar-polarization plane relative to the scatterers. Laboratory data will be analyzed in the light of characteristics computed with Discrete Dipole Approximation (DDA). Bulk scattering from multiple cylinders, ellipsoids, and fractures within glaciers will be simulated using DDA, allowing us to examine the ability of radar sounding to explore complex glacier interiors. They will borrow the radar equipment from the U.S. Army Cold Region Research and Engineering Laboratory (CRREL) and use CRREL facilities for the experiments. Broader Impacts: The project will provide research experience for two undergraduate students in both laboratory and theoretical analysis. Second, this research will contribute NSF's overall goals to understand the Arctic environment and its global impact. Third, this project will initiate collaboration between early-career scientists at different institutions. Fourth, this project can complement our ability to infer subsurface characteristics from future polarimetric radar sounding of the Earth, Mars, and other planets.

摘要马歇尔-0520541 MatsuokaOPP 0520465智力价值：这是来自华盛顿大学和科罗拉多大学的主要研究者的合作建议。 冰川内的水道将融化的水从冰川表面输送到冰川床。水润滑了河床，并在山地冰川中引入了显著的季节性和每日变化的冰速。目前的极地冰盖遇到轻微的表面融化，但冰盖沿海地区的持续变暖可能会改变这一点。如果水可以到达河床，冰流可能会显著加速，这是最近在格陵兰岛观察到的。这可能最终导致北极地区淡水的快速排放，大大加剧全球海平面上升。绘制水流路径及其时间变化图对于了解表面融化和河床润滑事件之间的空间和时间滞后以及更一般的冰川水文学和力学至关重要。利用探冰雷达进行遥感是研究冰内部时空变化的一种可行方法。雷达研究可能揭示的不仅仅是基岩和内部地层的几何形状。主要研究人员将进行实验室实验和计算机模拟，以研究冰川内散射体的形状，坡度，方位角，尺寸和内容（空气或水）如何改变无线电回波强度作为雷达频率和极化的函数。他们将测量在冷室内冰块内钻孔的散射，以及悬挂在开放空间内的热塑性聚合物的散射。后者给出了冰川中充满水的散射的模拟。在每个实验场地，他们将检查相对于散射体的雷达偏振平面的各种方位角的多个夹杂物的体散射。实验室数据将根据离散偶极近似（DDA）计算的特征进行分析。散装散射从多个圆柱体，椭球体，冰川内的裂缝将使用DDA模拟，使我们能够检查雷达探测探索复杂的冰川内部的能力。他们将从美国陆军寒冷地区研究和工程实验室（CRREL）借用雷达设备，并使用CRREL设施进行实验。更广泛的影响：该项目将为两名本科生提供实验室和理论分析方面的研究经验。其次，这项研究将有助于NSF的总体目标，以了解北极环境及其全球影响。第三，该项目将启动不同机构的早期职业科学家之间的合作。第四，这个项目可以补充我们的能力，从未来的地球，火星和其他行星的极化雷达探测推断地下特征。