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

职业：改进对温带冰川系统中冰雪融水储存和通量变化的估计

• 批准号: 2239668
• 负责人: Seth Campbell
• 金额: $ 62.39万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2028-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2239668&HistoricalAwards=false
• 关键词: CAREER; Improving; Estimates; Changing; Firn

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.

冰川是由每年的降雪形成的，而在夏季的几个月里，降雪并不会完全融化。随着时间的推移，积雪会凝结成冰川冰。降雪是介于雪和冰之间的一个高度渗透性的中间阶段，它经常在其孔隙空间中储存表面融化的水。不幸的是，我们无法很好地估计积雪中储存了多少融水，不同冰川之间的储水量是如何变化的，或者这种储水量是如何随着气候变化而变化的。该项目将确定几个降雪特性，如积雪厚度、孔隙体积、储水量以及位于阿拉斯加东南部的朱诺冰原上储水量随时间的变化。我们将使用实地观察和建模来回答这些问题，并更广泛地估计阿拉斯加和加拿大的降雪特性。这一点很重要，因为阿拉斯加和加拿大的冰川消融速度比地球上任何其他冰川系统都要快。因此，我们预计融水储存将会发生变化。积雪中储存的融水如果迅速从冰川中释放出来，可能会使海平面大幅上升，并影响其他地球系统，如海洋、微小生命形式和渔业。我们将把这个项目的结果用于我们为教室和门登霍尔冰川游客中心制作的互动教育视频游戏中，门登霍尔冰川游客中心每年接待超过60万名游客。我们将培训数百名学生使用这款游戏，并帮助进一步开发游戏。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夏令营，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)积雪厚度、密度、孔隙率、含水率和体积变化的时空变化。我们将使用本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，以了解降雪体积变化对融水储存、融水通量的影响，以及变化的融水过程对冰川下降的影响。我们之所以选择JIF进行这项研究，是因为它是对全球数千个经历降雪和变薄的温带冰川的恰当类比。这项研究将在每小时到每年的时间尺度和厘米到公里的空间尺度上表征融水和融水运动的空间和时间变异性，这些分辨率在任何冰川系统中都是罕见的。温带降雪的约束性很差，降雪的致密化模型还没有纳入熔融的经验观测。此外，关于降雪厚度、冰川退缩引起的降雪体积的变化以及与降雪融水储存和冰川下融水通量(从而影响下冰川生态系统)相关的变化的空间数据在很大程度上是未知的。这项提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比地球上任何其他冰川系统消退的速度都快，所以我们预计冰雪融水储存的变化将会发生。由于气候变化，积雪中储存的融水有可能使海平面大幅上升，并影响冰川下的陆地和海洋生态系统。作为该项目的一部分，我们将构建一个互动教育视频游戏，供教室和门登霍尔冰川游客中心使用(年访问量为600,000人)。我们还将培训500多名学生使用这款游戏，并帮助进一步开发游戏。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夏令营，集思广益，共同制定战略，以减少这些地区正在观察到的环境变化的影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。