EAGER: Extending Greenland glacier observations using newly-discovered aerial photographs

三次军事空降行动(美国空军：1940-1960年代，USCG：1970年代，USN：1970-1980年代)获得了数以万计的格陵兰航空照片。这些最近定位的照片可以在卫星观测之前洞察整个冰盖范围的冰川行为，但尚未被数字化或用于科学。目前，在20世纪80年代之前缺乏冰盖范围的观测，限制了我们对出口冰川动态长期演变进行建模的能力。研究小组将数字化20世纪40年代至80年代的历史图像，绘制格陵兰周边的冰川表面高程和终点位置，并在数据允许的情况下估计表面速度。通过提供更早以前的冰川信息，这一新的历史数据集可以用来改善建模冰川动态所需的约束条件，这将进一步提高冰川对气候变化反应的预测模型的准确性。工作流程和产品将在一个公共储存库中提供，供社区访问，并将设计一个教程，帮助研究人员对其他历史图像重复这一过程。最早的冰盖范围的表面高程图是使用20世纪80年代的数据制作的。该项目将扩展历史记录，包括20世纪40年代和70年代以及20世纪50年代和60年代大量出口冰川的格陵兰岛范围的冰川图像。该方法包括：将航空照片胶片底片数字化，使用军用飞行索引地图和实地笔记相结合的方式对照片中心进行地理定位，并使用运动结构摄影测量技术处理图像以生成地表高程。真实世界坐标是从稳定地形(例如，裸露的基岩)的当前高程中手动提取的局部峰值。这一方法已经成功地利用南极洲的历史航空照片进行了应用。该项目完成后，原始数字数据和准确估计的再现产品将可供公众查阅和分发。通过扩展格陵兰出口冰川动力学的时间尺度，这一新的历史数据集可以改善用于建模冰川动力学的约束条件，这将进一步提高冰川对气候变化响应的预测模型的精度。原始数据和衍生产品，包括地表高程、正射纠正图像和速度，将在北极数据中心存档，结果将与QGreenland和GHub共享，以扩大受众。还将设计一个教程，以允许其他人复制结果并将该方法应用于其他历史数据。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Three military airborne campaigns (USAF: 1940s-1960s, USCG: 1970s, USN: 1970s-1980s) acquired tens of thousands of aerial photographs of Greenland. These recently-located photographs can yield insight into ice-sheet wide glacier behavior prior to satellite observations but have not yet been digitized or used for science. Currently, lack of ice sheet-wide observations prior to the 1980s limits our ability to model the long-term evolution of outlet glacier dynamics. The research team will digitize historic images from the 1940s to 1980s, render glacier surface elevations and terminus positions for the perimeter of Greenland, and estimate surface velocities where the data permits. By providing glacier information further back in time, this new historical dataset can be used to improve constraints needed to model glacier dynamics which will further advance accuracy in predictive models of glacier response to climate change. The workflow and products will be available in a public repository for the community to access and a tutorial will be designed to help researchers repeat the process for other historical images. The earliest ice sheet-wide surface elevation maps were produced using data from the 1980s. This project will extend the historical record by including Greenland-wide glacier images from the 1940s and 1970s and from the 1950s and 1960s for a large number of outlet glaciers. The methodology includes: digitizing the air photo film negatives, geolocating the photo centers using a combination of military flight index maps and field notes, and processing the images using structure-from-motion (SfM) photogrammetry techniques to generate surface elevations. The real-world coordinates are manually extracted localized peaks from present-day elevations of stable terrain (e.g., exposed bedrock). This methodology has been successfully carried out using historical air photos from Antarctica. Upon the completion of this project, the raw digital data and rendered products with accuracy estimates will be made accessible for public distribution. By extending the temporal scale of Greenland outlet glacier dynamics, this new historical dataset can improve constraints used in modeling glacier dynamics which will further advance accuracy in predictive models of glacier response to climate change. Raw data and derived products, including surface elevation, orthorectified images, and velocities, will be archived at the Arctic Data Center and results will be shared with QGreenland and GHub to expand the audience. A tutorial will also be designed to allow others to reproduce the results and apply the methodology to other historical datasets.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.