Geoelectric Array Measurements of Sea Ice Porosity for Scientific and Operational In-situ Ice Property Assessments

海冰孔隙度的地电阵列测量，用于科学和可操作的原位冰特性评估

• 批准号: 0620124
• 负责人: Hajo Eicken
• 金额: $ 3.16万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0620124&HistoricalAwards=false
• 关键词: Geoelectric; Array; Measurements; Sea; Ice

This Small Grant for Exploratory Research is to develop and field-test methods for taking automated in situ dc resistivity measurements in sea ice. This will allow researchers to track the evolution of sea ice profile properties and to fill a current gap in the real-time monitoring of local ice conditions needed to assess ice strength and trafficability. Experimental work involves cross-borehole tomography measurements not previously performed in sea ice, and applying a microstructurally-realistic improved analysis of Wenner array soundings. Both methods exploit the large resistivity contrast between saline brine and pure ice, which makes the bulk resistivity of sea ice very sensitive to the connectivity of the interior brine volume. The proposed site for this work is landfast first-year ice near Barrow, Alaska, offering the benefits of accessible and readily-monitored ice and proximity to logistics support. The measurements will be complemented by full ice characterization data collected at a nearby mass balance site installed by our group as part of the nascent Alaska Ocean Observing System. Through collaboration with a solid-earth geophysicist with expertise in geoelectric array measurements, substantial synergistic benefits will also be derived from this project. Resistivity measurements in low temperature winter ice and during spring warming are ideally suited to assess theoretical predictions of the appearance and evolution of a 'percolation threshold' in the brine volume connectivity, and other critical transitions in ice profile properties, such as substantial reductions in ice strength in the high-porosity (10%) regime. The lack of appropriate field data (in particular time series) is significantly limiting progress in the research field, and this work aims to evaluate potential benefits that can be derived from novel geoelectric array measurements, owing to their high sensitivity, nondestructive nature and suitability for easy deployment in existing drifting sensor networks. This project will enhance research infrastructure by (1) developing a method (and corresponding instrumentation) that helps close a significant gap in drifting sensor networks which do not provide information on the state of the ice cover and its transport properties; (2) providing for a means to test and refine the applicability of percolation theory to a number of important sea ice geophysical phenomena; (3) laying the foundation for routine in situ monitoring of the state of the ice cover as applicable for engineering and operational applications (such as those relying on sea ice as a stable platform for transport and logistics); and (4) enhancing collaboration and exchange between the solid-earth geophysics and sea-ice glaciology communities to address common problems of materials at high homologous temperatures. These aspects of the project will be introduced into education by involving graduate students in the research and integrating the collaboration into an interdisciplinary seminar series examining porous media from volcanological and glaciological perspectives.

这项探索性研究的小额赠款将用于开发和现场测试海冰直流电阻率自动原位测量方法。这将使研究人员能够跟踪海冰剖面特性的演变，并填补目前在评估冰强度和可通行性所需的当地冰况实时监测方面的空白。实验工作涉及跨钻孔层析成像测量以前没有在海冰中进行，并应用温纳阵列探测的微观结构现实的改进分析。这两种方法都利用了盐水和纯冰之间的大电阻率对比，这使得海冰的体积电阻率对内部盐水体积的连通性非常敏感。这项工作的拟议地点是阿拉斯加州巴罗附近的陆地固定的第一年冰，提供了可访问和易于监测的冰和接近后勤支持的好处。这些测量将得到完整的冰特征数据的补充，这些数据是在附近的质量平衡站点收集的，该站点由我们的团队安装，作为新生的阿拉斯加海洋观测系统的一部分。通过与一位具有地电阵列测量专门知识的固体地球物理学家合作，还将从这一项目中获得巨大的协同效益。在低温冬季冰和春季变暖期间的电阻率测量非常适合于评估理论预测的外观和演变的“渗流阈值”的盐水体积连通性，以及其他关键的转变，在冰剖面特性，如冰强度的大幅减少在高孔隙度（10%）制度。缺乏适当的现场数据（特别是时间序列）显着限制了研究领域的进展，这项工作的目的是评估潜在的好处，可以从新的地电阵列测量，由于其高灵敏度，无损性和适用性，易于部署在现有的漂移传感器网络。该项目将通过以下方式加强研究基础设施：（1）开发一种方法，（和相应的仪器），这有助于填补漂移传感器网络中的一个重大空白，即不提供有关冰盖状况及其运输特性的信息;（2）提供一种手段，以测试和改进渗透理论对若干重要海冰地球物理现象的适用性;（3）为适用于工程和业务应用的冰盖状态的例行现场监测奠定基础（例如依赖海冰作为运输和物流稳定平台的国家）;加强固体地球物理学与海洋物理学的合作与交流，冰冰川学社区，以解决在高同源温度的材料的共同问题。该项目的这些方面将被引入教育，让研究生参与研究，并将合作纳入一个跨学科的研讨会系列，从火山学和冰川学的角度研究多孔介质。