Assessing topographic impacts on tropical glacier extent and moraine formation

由于气候变化，许多高山冰川目前正在退缩，几十年来的研究利用过去的冰川波动（前进和退缩）来了解过去气候变化的机制。然而，山地冰川也受到下伏地形的影响（例如，冰川上方的山脉高度和冰川下方的山谷坡度）。本项目结合乌干达和哥伦比亚山区过去冰川范围的重建，利用计算机模型研究地形对冰川范围的影响。这些热带山脉的足迹很小，使得相邻的山谷可能经历类似的气候条件，因此，冰川范围的任何差异应该是由于山谷之间的地形差异。此外，乌干达和哥伦比亚是少数几个可以获得多个相邻山谷冰川变化长期记录的热带地区。该项目将提高预测未来冰川变化和模拟景观演变的能力。它还将推动利用过去的冰川范围来了解过去气候变化的原因。该项目支持国际热带冰川研讨会和高中STEM活动的发展，旨在扩大代表性不足群体的参与。它还支持两名早期职业女性研究人员在一个女性仍然很少被代表的科学领域。该项目将使用冰川模型，结合现代气候数据和冰川冰碛（标记前冰川范围的山脊）的地表暴露年代，以评估地形对热带冰川范围和冰碛形成的影响。它有以下两个目标：1)利用具有理想数字高程模型的冰川模拟，评估特定地形特征的变化如何影响冰川范围；2)利用冰川模拟和冰碛地表暴露年代测定，评估地形变化如何影响两个热带山脉（乌干达的鲁文佐里山脉和哥伦比亚的内华达山脉）过去的冰川范围。该项目将提供为数不多的可用数据集之一，用于研究气候和地形对冰川范围的相对影响，从而提高冰川对未来气候变化响应的建模能力。它还将提高从冰川范围的地貌记录推断过去气候条件的能力。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。

Many mountain glaciers are currently retreating as a result of climate change, and decades of research have used past glacial fluctuations (advances and retreats) to understand the mechanisms of past climate change. Yet, mountain glaciers are also influenced by underlying topography (e.g., the mountain height above a glacier and valley slope beneath a glacier). This project examines the influence of topography on glacial extents using computer modeling in conjunction with reconstructions of past glacial extents in mountain ranges in Uganda and Colombia. The small footprint of these tropical mountain ranges makes it likely that neighboring valleys experience similar climate conditions and, thus, any differences in glacial extents should be due to topographic differences among the valleys. Moreover, Uganda and Colombia are among the few tropical locations where long-term records of glacial changes in multiple adjacent valleys may be obtained. The project will improve the ability to forecast future glacial changes and model landscape evolution. It will also advance the use of past glacial extents to understand the causes of past climate changes. The project supports an international tropical glacier workshop and the development of high school STEM activities that aim to broaden participation of underrepresented groups. It also supports two early career female researchers in a domain of science where women remain highly underrepresented.The project will use glacial modeling in combination with modern climate data and surface exposure dating of glacial moraines (ridges that mark former glacial extents) to assess topographic impacts on tropical glacial extents and moraine formation. It has the following two objectives: 1) assess how variations in specific topographic characteristics influence glacial extents using glacial modeling with idealized digital elevation models; and 2) assess how variations in topography influenced past glacial extents in two tropical mountain ranges (the Rwenzori Mountains in Uganda and the Sierra Nevada del Cocuy in Colombia) using glacial modeling and surface exposure dating of moraines. The project will provide one of the few datasets available to examine the relative impacts of climate and topography on glacial extents and, thus, advance the ability to model the response of glaciers to future climate changes. It will also improve the ability to infer past climate conditions from the geomorphic record of glacial extents.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.