Collaborative Research: Evaluating Snowlines Across the Tropics - The geomorphic imprint of tropospheric cooling and drying during the Last Glacial Maximum

合作研究：评估热带地区的雪线——末次盛冰期对流层冷却和干燥的地貌印记

• 批准号: 2102947
• 负责人: Alice Doughty
• 金额: $ 3.86万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2102947&HistoricalAwards=false
• 关键词: Collaborative; Research; Evaluating; Snowlines; Across

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).One of the great unsolved mysteries of Earth science is why the global climate oscillates between glacial periods, when multi-kilometer thick ice sheets spread across North America and northern Europe, and interglacial periods, when the Earth is much warmer and continental ice sheets are restricted to very high latitudes. Due to the integrated nature of the global climate system, unlocking this mystery requires knowledge of the chronologic order in which elements of the climate system change during transitions between glacial and interglacial periods and the magnitude of climate changes across latitudes. This project will leverage new and emerging remotely sensed datasets, including high-resolution satellite imagery and digital topography, to address the magnitude of climate changes in the tropical latitudes. Specifically, the researchers will use remotely sensed data to reconstruct former glacial extents throughout the tropics, where glaciers were restricted to the hard-to-reach highlands of high-elevation mountains. The research will produce a globally consistent dataset which will allow the testing of hypotheses about how much the Earth’s low latitudes cooled during the last glacial period, and how tropical changes play into major climate reorganizations. The project will rely heavily on a team of undergraduate researchers and will collaborate with the U.S. Ice Drilling Program to produce public educational material.The methodological approach is based on the realization that past changes in the global climate system can imprint on the topography of mountains. One of the clearest examples of this phenomenon is the transformation of mountain valleys by erosional patterns beneath glaciers. Glaciers only exist where temperatures are cold enough for year-round ice, so if glaciers leave telltale signs of their former extents in erosional and depositional landforms, then it is possible to calculate the position of the freezing line associated with these glaciers. By creating a global dataset of tropical glacial extents in carefully selected areas, the project will achieve three goals: 1) produce a global estimate of the lower bound of the tropical freezing line during the last glacial period 2) use numerical modeling of a “type example” tropical glacial system (Costa Rica) to evaluate the relationship between the annual freezing line and the elevation of glaciers in the tropics and 3) determine whether the lapse rate (change in temperature with elevation) was steeper during the last glacial period. Achieving these goals will advance the understanding of why the global climate has been subject to cyclic variations during Earth’s recent geologic history.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.

该奖项的全部或部分资金均根据《2021 年美国救援计划法案》（公法 117-2）提供。地球科学未解之谜之一是，为什么全球气候会在冰河期之间波动，此时冰层厚达数公里冰盖遍布北美和北欧，以及间冰期，由于全球气候的综合性质，地球变得更加温暖，大陆冰盖仅限于非常高的纬度。系统，解开这个谜团需要了解冰期和间冰期过渡期间气候系统要素变化的时间顺序以及跨纬度气候变化的幅度，该项目将利用新的和正在出现的遥感数据集，包括高分辨率。具体来说，为了解决热带纬度地区气候变化的严重程度，研究人员将利用卫星图像和数字地形来重建整个热带地区以前的冰川范围，这些地区的冰川仅限于热带地区。该研究将产生一个全球一致的数据集，该数据集将有助于检验有关地球低纬度地区在末次冰期期间变冷程度以及热带变化如何影响重大气候重组的假设。该项目将在很大程度上依赖本科生研究人员团队，并将与美国冰钻计划合作制作公共教育材料。该方法基于这样的认识：全球气候系统过去的变化可能会在地形上留下印记。这种现象最明显的例子之一是冰川下方的侵蚀模式对山谷的改造，只有在温度足够冷、适合全年结冰的地方，所以如果冰川在侵蚀和沉积过程中留下了明显的迹象。通过在精心挑选的地区创建热带冰川范围的全球数据集，该项目将实现三个目标：1）产生一个与这些冰川相关的冰冻线位置。对末次冰河期热带冰冻线下限的全球估计 2) 使用“典型”热带冰川系统（哥斯达黎加）的数值模拟来评估年度冰冻线与冰川海拔之间的关系3）确定上一个冰河期的递减率（温度随海拔的变化）是否更陡。实现这些目标将有助于理解为什么全球气候在地球近代期间受到周期性变化的影响。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。