Collaborative Research: RUI: Frontal Ablation Processes on Lake-terminating Glaciers and their Role in Glacier Change

世界各地的冰川正在迅速变化，以应对变暖的温度。在水中结束的冰川通常很薄，而且比在陆地上结束的冰川退缩得更快，因为它们通过水线以下的融化和冰山的破裂而失去冰。尽管许多过去的研究人员研究了以海洋为终点的冰川的工作原理，但很少有人关注以湖泊为终点的冰川，以及这两种类型的冰川可能会有什么不同的功能。在我们的项目中，我们将研究一组三个最终形成湖泊的冰川；收集关于冰川本身、它们最终到达的湖泊以及在冰川和湖泊之间移动的沉积物的信息。研究人员将与阿拉斯加原住民科学与工程计划(ANSEP)以及朱诺冰原研究计划(JIRP)的学生合作，以确定这些湖泊造成了多少额外的冰流失，以及这些冰流失对冰川在未来几十年的变化有多大影响。总体而言，冰川末端的湖泊在过去几十年里迅速增长。然而，目前尚不清楚湖泊的增长是对冰川消退的被动反应，而冰川消退在很大程度上是由大气条件的变化(气温变暖和/或冬季降雪量减少)推动的，还是湖泊本身通过增加冰川融化来推动冰川消退。我们的团队汇集了一位冰川学家、一位海洋学家和一位北极地球系统模型师，以量化冰山生产和水下融化造成的冰量损失，这三条大型冰川排干了朱诺冰原，最终形成湖泊。调查人员将使用声纳系统、从船上投放的探头以及浮标安装的仪器收集对湖中条件(深度、温度、悬浮泥沙浓度)的短期和长期观测。调查人员还将使用地面雷达、GPS系统和卫星观测来测量冰川的厚度和速度。这些数据集将被输入到计算机模型中，以估计由于这个湖而损失了多少冰，这种情况在未来将如何变化，以及湖的存在将在多大程度上改变21世纪冰川的总冰消失量。这些信息将帮助我们了解未来几十年世界各地冰川变化的速度，这将使我们能够更好地管理下游生态系统和水资源，并促进气候变化的适应能力。除了科学目标，该项目还将通过与本科生合作开发计算研讨会并扩大地球科学界的代表性来加强STEM工作人员。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。

Glaciers around the world are changing rapidly in response to warming temperatures. Glaciers that end in water often thin and retreat faster than those ending on land because they lose ice through melt below the waterline and through the breaking off of icebergs. While many past researchers have studied the workings of glaciers ending in the ocean, very few have focused on glaciers that end in lakes and how these two types of glaciers might function differently. In our project, we will study a set of three glaciers that end in lakes; collecting information about the glaciers themselves, the lakes they end in, and the sediment moving between the glacier and lake. The investigators will work with students from the Alaska Native Science and Engineering Program (ANSEP) as well as the Juneau Icefield Research Program (JIRP) to identify how much extra ice is being lost due to these lakes and how much that ice loss matters for how the glaciers will change over the coming decades.Globally, lakes at the end of glaciers have grown rapidly over the past decades. However, it remains unclear whether lakes are growing as a passive response to glacier retreat that is largely driven by changing atmospheric conditions (warming air temperature and/or declining winter snowfall), or whether the lakes themselves are driving this retreat by enabling extra ice loss. Our team brings together a glaciologist, an oceanographer, and an Arctic earth system modeler to quantify the amount of ice lost through iceberg production and underwater melt on three large glaciers draining the Juneau Icefield that end in lakes. The investigators will collect both short- and long-term observations of conditions in the lake (depth, temperature, suspended sediment concentration) using a sonar system and probes cast from a boat, as well as buoy-mounted instruments. The investigators will also measure glacier ice thickness and speed using ground-based radar, GPS systems, and satellite observations. These datasets will be fed into computer models to estimate how much additional ice is being lost due to the lake, how this will change in the future, and how much the lake’s presence will alter the glacier’s overall ice loss over the 21st century. This information will help us understand how fast glaciers across the world will change over the coming decades, which will enable better management of downstream ecosystems and water resources, as well as promoting climate change resilience. In addition to the science objectives, the project will strengthen the STEM workforce by partnering with undergraduate programs to develop computational workshops and broaden representation within the earth science community.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.