Postdoctoral Fellowship: OPP-PRF: Spatiotemporal Evolution of Firn Hydrology on the Juneau Icefield, Alaska

阿拉斯加的高山冰川构成了地球冰冻圈变化最快的部分，总共占全球海平面陆地冰损失的25%。了解融水流经冰川的物理过程仍然是预测冰川行为和环境影响的关键挑战。具体地说，降雪(刚落下的雪压实成冰川冰的物质)影响着融水流经冰川的速度、体积和地球化学组成。在广泛的层面上，流经冰雪的水流是描述冰川行为、冰川质量损失和增加，以及最终海平面、下游生态和区域水资源的基本特征。这项研究使用建模和来自阿拉斯加东南部朱诺冰原的各种新的和历史的现场数据，以促进对气候变化背景下阿拉斯加冰川积雪中融水流动的理解。该项目通过加强朱诺冰原研究方案(JIRP)与阿拉斯加土著社区之间的联系，推动包容性研究实践。该项目：(1)测量地表融化和降雪性质的变化，这是了解朱诺冰原降雪水文变化的关键，以及(2)建立在水同位素地层学的新应用基础上，以确定降雪中融水入渗的时间和变异性的变化。要实现这些目标，需要汇集穿冰雷达数据、水同位素记录、气象数据和其他现场测量数据。这一综合数据集将有助于分析现场测量和执行融水-同位素模型模拟，以量化地表融化速度、融化时间、融化渗透速率、降雪温度和冰层水文特征，如积雪含水层和冰层的形成和演变，在分季节和年度间的时间段。由该项目产生的降雪水文学的全面评估将促进对阿拉斯加冰川变化的了解，并对改善对格陵兰和南极冰盖的了解具有更广泛的影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The alpine glaciers of Alaska constitute some of the most rapidly changing parts of the Earth’s cryosphere and collectively contribute 25% of land-ice loss to global sea level. Understanding the physical processes involved in meltwater flow through a glacier remains a key challenge in predicting a glacier’s behavior and environmental impact. Specifically, the firn (the material through which freshly fallen snow compacts into glacial ice) influences the speed, volume, and geochemical composition of meltwater flow through a glacier. Water flow through the firn is, on a broad level, fundamental for characterizing glacier behavior, glacier mass loss and gain, and ultimately sea level, downstream ecology, and regional water resources. This research uses modeling and a variety of new and historical field data from the Juneau Icefield in Southeast Alaska to advance understanding of meltwater flow through the firn on Alaskan glaciers within the context of climate change. This project advances inclusive research practices by strengthening connections between the Juneau Icefield Research Program (JIRP) and Alaska Indigenous communities. This project: (1) measures changes in surface melt and firn properties that are key to understanding changes in firn hydrology on the Juneau Icefield, and (2) builds on novel applications of water-isotope stratigraphy to determine changes in timing and variability of meltwater infiltration in the firn. Accomplishing these objectives requires the assembly of ice-penetrating radar data, water-isotope records, meteorological data, and other in-situ measurements. This comprehensive dataset will facilitate analyses of field measurements and execution of meltwater-isotope model simulations to quantify surface-melt rates, melt timing, melt-infiltration rates, firn temperature, and englacial hydrological features such as firn-aquifer and ice-layer formation and evolution over sub-seasonal and inter-annual time periods. The comprehensive assessment of firn hydrology generated by this project will advance understanding of glacier change in Alaska and with broader implications for improved understanding of the Greenland and Antarctic ice sheets.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.