SGER: High Resolution Radar Mapping of Ice Thickness and Near-Surface Layers in Northeast Greenland

首席调查人员建议使用两个紧凑的宽带雷达绘制冰芯周围的近地表和深层内部冰层图，该冰芯将于2006年5-6月在格陵兰岛东北部540米厚的沿海Flade Isblink冰帽上钻探。这项工作将是由丹麦研究人员领导的多国合作努力的一部分，目的是描述气候变化与冰盖和海冰演变之间的关系。低功率雷达、它们的天线和便携式发电机将安装在南森雪橇上，并以核心钻探现场为中心，以大约9公里x 9公里的网格拉在雪地摩托后面，以绘制累积速率、累积变异性、厚度和流经穹顶的特性。这两个雷达系统已经在格陵兰岛和南极洲进行了广泛的开发和测试，可以在不进行额外修改的情况下部署。该提议利用了哥本哈根大学团队提供的额外后勤支持。所有合作者都同意共享数据集。该项目的设备维护、数据处理和分析以及结果发布等费用将由CReSIS(冰盖遥感中心)承担。人们对格陵兰北部的古气候变化以及它与格陵兰其他地区的古气候变化的关系知之甚少。科学上的价值将是利用探地雷达对这一偏远和研究很少的地区进行勘探，以便为预测气候变化和海平面上升的冰盖动力学和演化的高分辨率数值模型提供输入和验证。冰芯和雷达研究提供了该地区冰盖演化和气候历史的更完整图景。雷达测量对于在冰盖模型中使用的核心站点之外的横向推断冰的内部结构和历史至关重要，核心站点实际上是冰盖上的点源。同时，需要测量冰芯温度和密度，以将雷达剖面从旅行时间转换到深度域，以获得准确的近地表堆积剖面和ECM(电导率测量)和深度/年龄剖面，以便为绘制火山活动造成的深部等时线提供地面真实情况。雷达剖面还将：1)解决冰盖厚度和层变形，2)扩展内部层结构和冰流特性，3)查看地形对堆积的影响。在积累剖面的帮助下，首席调查人员希望了解冰帽是否挺过了早期全新世气候最佳时期，以及为什么在冰盖的质量平衡略为负、冰盖变薄主要发生在较低的沿海地区时，冰帽以大约50厘米/年的速度增长。该研究小组目前有一个强大的外展计划，并将利用CReSIS的资源：1)提供期刊和图片，以便在我们的网站上发布；2)为K-12学生开发游记和课程材料；3)为哈斯凯尔印第安人民族大学的学生举办关于Flade Isblink活动的讲座。该项目的所有冰芯和雷达数据将在从野外返回后一年内提交给NSIDC。

ABSTRACTLairdOPP-0608181The Principal Investigators propose to use two compact, wideband radars to map near -surface and deep internal ice layers around an ice core to be drilled on the 540 m thick, coastal Flade Isblink Ice Cap in NE Greenland in May - June, 2006. This work will be part of a collaborative, multi-national effort led by Danish researchers to characterize the relationship between climate change and the evolution of the ice caps and sea ice. The low-power radars, their antennas and a portable generator will be mounted on a Nansen sled and pulled behind a snowmobile in an approximately 9 km x 9 km grid centered on the core drill site to map accumulation rates, accumulation variability, thickness and flow properties across the dome. The two radar systems have already been developed and tested extensively in both Greenland and Antarctica and can be deployed without additional modifications.The proposal leverages additional logistical support provided by the University of Copenhagen team. All collaborators have agreed to share data sets. The costs for this project, such as equipment maintenance, data processing and analysis, and publication of results will be borne by the CReSIS (Center for Remote Sensing of Ice Sheets).Intellectual Merit Little is known about paleoclimatic change in northern Greenland andhow it is related to paleoclimatic change in the rest of Greenland. The scientific merit will be the exploration of this remote and little studied region with ground penetrating radar to provide input to, and validation of, high-resolution numerical models of ice sheet dynamicsand evolution for predicting climate change and sea - level rise. Ice core and radar studiesprovide a more complete picture of the evolution of the ice cap and the climate history of that region. Radar measurements are critical for extrapolating the internal structure and history of the ice laterally beyond the core site, which is effectively a point source on the ice cap,for use in ice sheet models. At the same time, ice core temperature and density measurements are necessary to convert the radar profiles from travel time into depth domain for accurate near - surface accumulation profiles and ECM (Electrical Conductivity Measurements) and depth/age profiles are required to provide ground truth for mapping deep isochrones due to volcanic activity. The radar profiles will also: 1) resolve ice sheet thickness and layer deformation, 2) expand on internal layer structure and ice flow properties, and 3) look at topographic effects on accumulation. With the aid of the accumulation profiles, the Principal Investigators hope to learn if the ice cap survived the early Holocene Climatic Optimum and why it is growing at a rate of about 50 cm/y when the mass balance of the ice sheet is slightly negative and thinning predominates in lower, coastal areas.Broader Impacts An electrical engineering graduate student will be directly involved in thisproject, both in the field and in the lab, assisting with radar operation, data analysis and visualization, linking radar data to glaciological issues addressed by this project. The research group currently has a strong outreach program and will leverage CReSIS resources to: 1) provide a journal and pictures for posting on our website, 2) develop a travelogue and course materials for K -12 students, and 3) present lectures on Flade Isblink activities for students at Haskell Indian Nations University. All ice core and radar data from this project will be submitted to NSIDC within one year after returning from the field.