MRI: Development of a High-power, Large Antenna Array and Ultrawideband Radar for a Basler for Sounding and Imaging of Fast-flowing Glaciers and Mapping Internal Layers

1229716/Hale该核磁共振奖支持开发用于极地冰盖高分辨率测量的雷达仪器，以实现广泛的科学调查。具体地说，将开发高功率、超宽带、大天线多通道相干雷达和有源目标/多基地接收机(ATMR)。超宽带雷达将在150-600 MHz的频率范围内运行，具有24-36个单元的大型交叉轨道阵列。为了探测冰盖边缘和表面非常粗糙的快速流动的冰川，需要使用大型交叉轨道阵列。雷达探测这些地区的冰层极具挑战性，因为表面杂波--粗糙的冰面产生的偏离垂直的反向散射信号--这可能会掩盖来自冰床的微弱回波。交叉轨道阵列需要减少这种表面杂波，以测量冰的厚度和表征冰床的条件，以包括冰是否冻结在冰床上或是否在一层水上滑动。水的存在润滑了冰床，导致冰移动得更快。ATMR被用来校准雷达和测量冰损失，以估计床上的条件。现有的模型可以模拟长期和大范围的冰盖演变，但它们无法模拟和预测卫星传感器观测到的短期和快速波动。这主要是因为导致短期波动的潜在过程的物理学在这些模型中理解和表现得很差。此外，缺乏关于所需分辨率的边界条件的关键信息，严重阻碍了开发下一代冰盖模型，以模拟观测到的变化并预测未来对气候变暖的反应。使用目前正在开发的改进的冰盖模型预测极地冰盖在变暖气候中的反应，需要根据冰层厚度和表面高度测量估计的海床地形和基本条件。将进行模拟实验或模拟，以确定描述快速流动的冰川和边缘所需的最佳分辨率。仪器的设计将满足这些要求。此外，超宽带雷达将通过对冰床界面进行高分辨率成像并绘制从地表到海床的内部层图，帮助选择深部岩心钻探的最佳地点，从而更准确地确定冰芯钻探地点的选择。这一核磁共振成像项目的学术价值在于开发和部署了新的超宽带雷达技术，这将有助于我们了解快速变化的出口冰川地区的关键冰盖过程，确保成功地选择具有100多万年气候记录的深层冰芯的选址，并能够成功地绘制冰内和冰下的水文网络图。该项目的更广泛影响包括：将开发的技术应用于其他地球物理研究，包括测量海冰和永冻土以及测量陆地上的土壤水分、植被和积雪厚度；本科生和研究生的参与；与工业界的伙伴关系；以及三个国际合作。该项目将通过将研究生和本科生与技术和仪器开发、现场观察和科学分析结合起来，为培养下一代科学家做出重大贡献。广泛的国际伙伴关系为美国教职员工和学生提供了参与真正全球化研究的独特机会。该项目还包括与谷歌公司的行业合作，谷歌正在为机载相机系统提供匹配支持，并对学生进行相机使用方面的培训。收集到的图像以及相应的冰床地貌雷达结果将通过谷歌地球和谷歌地图向公众公布。

1229716/HaleThis MRI award supports the development of radar instrumentation for fine-resolution measurements on polar ice sheets to enable a wide range of scientific investigations. Specifically, a high-power, ultra- wideband, large-antenna multi-channel coherent radar, and an active target/multistatic receiver (ATMR) will be developed. The ultra-wideband radar will operate over the frequency range of 150-600 MHz with a large cross-track array of 24-36 elements. The large cross-track array is required to sound ice in ice-sheet margins and fast-flowing glaciers with very rough surfaces. Radar sounding of ice in these areas is extremely challenging because of surface clutter - off-vertical backscattered signals produced by the rough ice surface - and this can mask weak echoes from the ice bed. The cross-track array is required to reduce this surface clutter to measure ice thickness and characterize conditions at the ice bed, to include whether or not ice is frozen to the bed or sliding on a film of water. The presence of water lubricates the ice bed and that results in ice moving much faster. The ATMR is used to calibrate radars and measure ice loss to estimate conditions at the bed. Existing models can simulate long-term and large-scale evolution of ice sheets, but they are incapable of simulating and predicting short-term and rapid fluctuations observed with satellite sensors. This is mainly because the physics of the underlying processes causing short-term fluctuations are poorly understood and represented in these models. Also the lack of critical information on boundary conditions at the required resolution has been a serious impediment to developing next-generation ice sheet models for simulating observed changes and predicting future response in a warming climate. Bed topography, estimated from ice thickness and surface elevation measurements, and basal conditions are required to predict the response of polar ice sheets in a warming climate using improved ice-sheet models currently in development. Modeling experiments or simulations will be performed to determine the optimum resolution required to characterize fast flowing glaciers and margins. The instrumentation will be designed to meet these requirements. Additionally, the ultrawideband radar will facilitate the process of selecting optimum site for deep core drilling by enabling fine-resolution imaging of the ice-bed interface and mapping internal layers from the surface to the bed, so the choice of ice core drill sites will be more precisely determined. The intellectual merit of this MRI project is the development and deployment of new ultra-wideband radar technology that will contribute to our understanding of key ice sheet processes in rapidly changing outlet glacier regions, ensure successful site selection for a deep-ice core with a climate record of more than a million years, and enable successful mapping of hydrological networks within and under the ice. The broader impacts of this project involve: application of the developed technology to other geophysical studies, including measurements over sea ice and permafrost and measurements of soil moisture, vegetation, and snow thickness over land; involvement of undergraduate and graduate students; partnerships with industry; and three international collaborations. The project will contribute significantly to the training of next generation of scientists by integrating graduate and undergraduate students with the technology and instrumentation development, field observations, and scientific analysis. Broad international partnerships provide unique opportunities for U.S. faculty, staff and students to participate in truly globalized research. This project also includes an industry partnership with Google Inc., which is providing matching support for an airborne camera system and student training in the use of the camera. Images collected along with the corresponding radar results of ice-bed topography will be made available to the public through Google Earth and Google Maps.