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

EAGER：利用新发现的航空照片扩大格陵兰冰川观测范围

• 批准号: 2135018
• 负责人: Leigh Stearns
• 金额: $ 29.99万
• 依托单位: University of Kansas Center for Research Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2135018&HistoricalAwards=false
• 关键词: EAGER; Extending; Greenland; glacier; observations

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.

三次军事空降行动（USAF: 1940 - 60年代，USCG: 1970年代，USN: 1970 - 80年代）获得了数万张格陵兰岛的航空照片。这些最近定位的照片可以在卫星观测之前深入了解冰盖冰川的行为，但尚未被数字化或用于科学研究。目前，缺乏20世纪80年代之前的全冰原观测，限制了我们模拟出口冰川动力学长期演变的能力。研究小组将对20世纪40年代至80年代的历史图像进行数字化处理，绘制格陵兰岛周边冰川的表面高度和终点位置，并在数据允许的情况下估计地表速度。通过提供更早的冰川信息，这个新的历史数据集可以用来改善冰川动力学建模所需的约束条件，这将进一步提高冰川对气候变化响应的预测模型的准确性。工作流程和产品将在一个公共存储库中供社区访问，并将设计一个教程，以帮助研究人员重复其他历史图像的过程。最早的冰盖表面高程图是用20世纪80年代的数据绘制的。该项目将扩大历史记录，包括20世纪40年代和70年代格陵兰岛范围的冰川图像，以及20世纪50年代和60年代大量出口冰川的冰川图像。该方法包括：将航空照片底片数字化，结合军事飞行索引地图和实地记录对照片中心进行地理定位，并使用运动结构（SfM）摄影测量技术处理图像以生成地表高程。真实世界的坐标是从稳定地形（例如裸露的基岩）的当前海拔中手动提取的局部峰值。这种方法已经成功地使用了来自南极洲的历史航空照片。项目完成后，将会向公众提供原始数字数据和带有精度估计的渲染产品。通过扩展格陵兰出口冰川动态的时间尺度，这一新的历史数据集可以改善冰川动力学建模的约束条件，从而进一步提高冰川对气候变化响应的预测模型的准确性。原始数据和衍生产品，包括地表高程、正校正图像和速度，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，允许其他人复制结果并将该方法应用于其他历史数据集。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。