Collaborative Research: IPY: Dynamic Controls on Tidewater Glacier Retreat

知识价值。首席调查员将研究阿拉克萨中南部迅速退缩的哥伦比亚冰川的动态变化。像哥伦比亚冰川这样的潮汐冰川（twg）终止于海洋，值得特别关注，因为它们表现出世界上所有冰川中最大和强烈的非线性动态体积变化。此外，大多数冰盖质量损失发生在海洋末端的出口冰川，这些冰川表现出与TWG非常相似的动力不稳定性。然而，人们对这些冰川对气候强迫的反应仍然知之甚少。他们将继续在哥伦比亚冰川进行无与伦比的30年观测记录，并研究它与迅速退缩的格陵兰出口冰川之间的相似之处。项目目标旨在预测未来TWG体积变化的能力，TWG体积变化是全球海平面上升的主要组成部分。包括垂直航空摄影测量（以及随后的特征跟踪）、地面延时摄影测量、机载雷达、GPS测量和气象监测在内的各种测量将为应力和流场的逆和正演建模提供强大的约束。更好地了解气候强迫、冰川动力学和冰量变化之间的相互作用的必要性得到了广泛的认可，并在IPCC 2007年决策者摘要、SEARCH实施计划、IPY欧盟倡议GLACIODYN和NSF呼吁建立北极观测网络中提出了更好的冰川观测建议。SEARCH实施计划和GLACIODYN都将哥伦比亚冰川特别列为关键冰川学地点。这项研究与GLACIODYN的目标非常一致，并得到了指导委员会的认可。更广泛的影响。由于数量众多，小冰川仍然主导着冰冻圈对全球海平面上升的贡献。这一贡献中最大的不确定性来自TWG，其中体积变化由未测量和知之甚少的动力学过程控制。正如海因里希事件所证明的那样，冰川和冰盖的快速淡水输入直接影响洋流，而灾难性的退缩影响了全球气候。twg的快速体积变化引起的区域和局部变化影响了峡湾的几何形状和环流，同时暴露了新的陆地，这导致了陆地生态系统的巨大变化，包括一些观测到的最强均衡反弹信号。这项研究将通过与对推进陆地摄影测量方法感兴趣的欧洲同事的合作，以及与a . Vieli的正演建模合作，建立新的伙伴关系。这项活动是科罗拉多大学和华盛顿大学研究人员的合作，有很强的教育成分，包括本科生和两名研究生。外联活动将通过INSTAAR和国家冰雪数据中心（NSIDC）提供的渠道进行，主要调查人员在阿拉斯加州瓦尔迪兹和华盛顿大学开展当地外联活动。数据将提供给GLACIODYN外联协调员，后者将使用虚拟地球技术使项目可视化。研究结果将刊登在同行评议的期刊上，在国家和国际会议上的发言，以及以软件和算法开发为重点的小型讲习班上，并将存档于国家科学研究中心和联安办事处

Intellectual merit. The Principal Investigators will study both ongoing and historical changes in dynamics at the rapidly retreating Columbia Glacier, in south central Alaksa. Tidewater glaciers (TWGs) like Columbia Glacier terminate in the ocean and merit special attention because they exhibit some of the largest and strongly non-linear dynamic volume changes of all glaciers worldwide. In addition, most ice sheet mass loss occurs at marine-ending outlet glaciers that display dynamic instabilities very similar to TWG. Yet, the response of these glaciers to climate forcing remains very poorly understood. They will continue an unmatched 30-year record of observations at Columbia Glacier and to study the similarities between it and the rapidly retreating Greenland outlet glaciers. Project goals are aimed at a predictive capability for future TWG volume changes, which are a dominant constituent of global sea level rise. A variety of measurements including vertical aerial photogrammetry (and subsequent feature-tracking), terrestrial time-lapse photogrammetry, airborne radar, GPS surveying, and meteorological monitoring will provide robust constraints for both inverse and forward modeling of the stress and flow fields. The need for a better understanding of the interaction between climate forcing, glacier dynamics and ice volume change is widely recognized and has led to recommendations for better glacier observations in the the IPCC 2007 Summary for Policymakers, the SEARCH Implementation Plan, the IPY E.U. initiative GLACIODYN, and the NSF call for an Arctic Observing Network. Both the SEARCH Implementation Plan and GLACIODYN list Columbia Glacier specifically as a key glaciological site. This study strongly aligned with the goals of GLACIODYN, and has been endorsed by the steering committee. Broader impacts. Because of their large numbers, small glaciers still dominate the cryosphere's contribution to global sea level rise. The largest uncertainties in this contribution are from TWG where volume changes are controlled by unmeasured and poorly understood dynamical processes. Rapid freshwater inputs of glaciers and ice sheets directly affect ocean currents, and catastrophic retreats have affected global climate, as evidenced through Heinrich Events. Regional and local changes from rapid volume change at TWGs affect fjord geometry and circulation while exposing new landmass, which causes large changes in terrestrial ecosystems including some of the strongest observed isostatic rebound signals. This study will create new partnerships through collaborations with European colleagues interested in advancing terrestrial photogrammetric methodology, and through a forward modeling collaboration with A. Vieli. The activity is a collaboration between researchers from the Universities of Colorado and Washington, and has a strong educational component, involving undergraduates, and two graduate students. Outreach will occur through channels offered by INSTAAR and National Snow and Ice Data Center (NSIDC), local outreach activities conducted by the Principal Investigators in Valdez, Alaska and University of Washington. Data will be provided to the GLACIODYN outreach coordinator, who will use Virtual Globe technology for project visualization. Results will appear in peer reviewed journals, presentations at national and international meetings, and small workshops focusing on software and algorithm development, and will be archived at NSIDC and UNAVCO