CAREER: Improving Estimates of Changing Firn Meltwater Storage and Flux in Temperate Glacier Systems

冰川是由每年的降雪形成的，这些降雪在夏季不会完全融化。随着时间的推移，这些积累的雪凝结成冰川冰。雪层是介于雪和冰之间的高度多孔的中间阶段，通常将表面融水储存在其孔隙空间中。不幸的是，我们不能很好地估计冰川中储存了多少融水，冰川之间的储水量如何变化，或者由于气候变化，储水量如何变化。该项目将确定位于阿拉斯加东南部的朱诺冰原的几种地层性质，如地层厚度、孔隙体积、储水量以及储水量随时间的变化。我们将使用现场观察和建模来回答这些问题，并在阿拉斯加和加拿大更广泛地估计公司属性。这一点很重要，因为阿拉斯加和加拿大的冰川退缩（融化）速度比地球上任何其他冰川系统都要快。因此，我们预计融水储存量将发生变化。储存在冰川中的融水如果迅速从冰川中释放出来，有可能使海平面大幅上升，并影响其他地球系统，如海洋微观生命形式和渔业。我们将利用这个项目的成果，为教室和每年接待60多万游客的门登霍尔冰川游客中心制作一个互动教育视频游戏。我们将培训数百名学生使用游戏，并帮助他们进一步开发游戏。最后，该项目将部分支持阿拉斯加和加拿大西北部土著社区的年度文化营，在那里将制定减少环境变化影响的战略。该项目将量化阿拉斯加东南部和加拿大西北部朱诺冰原（JIF）冰层厚度、密度、孔隙度、含水量和体积变化的时空变化。我们将利用该项目期间获得的一系列观测数据、先前获得的数据、数据同化和建模，来了解冰川体积变化对融水储存、融水通量的影响，以及融水过程变化对冰川下游的影响。我们之所以选择JIF进行这项研究，是因为它是全球数以千计的温带冰川经历融化和变薄的适当模拟。本研究将在小时到年的时间尺度和厘米到公里的空间尺度上描述冰川融水和融水运动的时空变异性，这些分辨率很少在任何冰川系统中实现。温带铁石的约束很差，铁石的致密化模型还没有纳入熔体的经验观察。此外，关于冰川厚度、冰川退缩导致的冰川体积变化以及冰川融水储存和冰川下融水通量（从而影响冰川下生态系统）的相关变化的空间数据在很大程度上是未知的。这一建议将有助于应对这些挑战。这一点很重要，因为阿拉斯加和加拿大的冰川退缩的速度比地球上任何其他冰川系统都要快，所以我们预计冰川融水储存量会发生变化。由于气候变化，公司储存的融水有可能大幅提高海平面，并影响冰川下的陆地和海洋生态系统。作为这个项目的一部分，我们将制作一个互动式教育视频游戏，用于教室和门登霍尔冰川游客中心（每年有60万游客）。我们还将培训500多名学生使用游戏，并帮助他们进一步开发游戏。最后，该项目将部分支持阿拉斯加和加拿大西北部土著社区的年度文化营，以集思广益的合作战略，减少这些地区观察到的环境变化的影响。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。

Glaciers are created from annual snowfall which does not entirely melt during summer months. Over time, this accumulated snow condenses to form glacier ice. Firn is a highly porous middle stage between snow and ice which often stores surface meltwater in its pore space. Unfortunately, we don’t have a good estimate of how much meltwater is stored in firn, how this water storage varies from glacier to glacier, or how this storage amount is changing due to climate change. This project will determine several firn properties such as firn thicknesses, pore volume, water storage, and changes in water storage over time across the Juneau Icefield located in Southeast Alaska. We will use field observations and modeling to answer these questions and to estimate firn properties more broadly across Alaska and Canada. This is important because Alaska and Canada glaciers are retreating (melting) faster than any other glacier system on Earth. Therefore, we expect changes in meltwater storage to occur. Meltwater stored in firn has the potential to raise sea level by a significant amount and impact other Earth systems such as ocean microscopic life forms and fisheries if it is rapidly released from glaciers. We will use results from this project in an interactive educational video game we build for classrooms and the Mendenhall Glacier Visitors Center which receives over 600,000 visitors per year. We will train hundreds of students to use the game and help with further game development. Lastly, this project will partially support an annual Culture Camp with indigenous communities in Alaska and Northwestern Canada where strategies for reducing impacts from environmental changes will be developed.This project will quantify spatial and temporal variations in firn thickness, density, porosity, water content, and volume change, across the Juneau Icefield (JIF) in Southeast Alaska and Northwest Canada. We will use a range of observations acquired during this project, previously acquired data, data assimilation, and modeling, to understand the impacts of firn volume change on meltwater storage, meltwater flux, and down-glacier impacts from changing meltwater processes. We have selected the JIF for this study because it is an appropriate analog to thousands of temperate glaciers across the globe experiencing firn loss and thinning. This research will characterize spatial and temporal variability of meltwater and meltwater movement within firn over hourly-to-yearly timescales and cm-to-km spatial scales, resolutions rarely achieved across any glacier system. Temperate firn is poorly constrained and densification models of firn do not yet incorporate empirical observations of melt. Additionally, spatial data on firn thickness, changes to firn volume due to glacier retreat, and the associated changes to firn meltwater storage and down-glacier meltwater flux (thereby influencing down-glacier ecosystems), are largely unknown. This proposal will help tackle these challenges. This is important because Alaskan and Canadian glaciers are retreating faster than any other glacier system on Earth, so we expect changes in firn meltwater storage to occur. Meltwater stored in firn has the potential to raise sea level by a significant amount and impact down-glacier terrestrial and marine ecosystems due to climate change. As part of this project, we will build an interactive educational video game for use in classrooms and the Mendenhall Glacier Visitors Center (600,000 annual visitors). We will also train over 500 students to use the game and help with further game development. Lastly, this project will partially support an annual Culture Camp with indigenous communities in Alaska and Northwestern Canada to brainstorm collaborative strategies for reducing impacts from environmental changes being observed in these regions.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.