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，以应对全球变暖。末端在水中的冰川通常比末端在陆地上的冰川更薄，退缩得更快，因为它们通过水线以下的融化和冰山的断裂失去了冰。虽然过去的许多研究人员研究了以海洋为终点的冰川的作用，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如何发挥不同的作用。在我们的项目中，我们将研究一组三个冰川，它们的尽头是湖泊；收集冰川本身的信息，它们最终进入的湖泊，以及冰川和湖泊之间移动的沉积物。研究人员将与阿拉斯加两个不同项目的学生合作，确定这些湖泊造成了多少额外的冰损失，以及这些冰损失对未来几十年冰川变化的影响有多大。在全球范围内，冰川末端的湖泊在过去几十年里迅速增加。然而，目前尚不清楚湖泊的增长是对冰川退缩的被动反应，而冰川退缩主要是由大气条件的变化（气温升高和/或冬季降雪量的减少）引起的，还是湖泊本身通过使额外的冰损失来推动这种退缩。我们的团队汇集了一名冰川学家、一名海洋学家和一名北极地球系统建模师，量化了由于冰山产生和三个大冰川的水下融化而损失的冰量，这些冰川将朱诺冰原排水，最终形成湖泊。调查人员将使用声纳系统和从船上投下的探测器，以及安装在浮标上的仪器，收集湖中条件（深度、温度、悬浮沉积物浓度）的短期和长期观测数据。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计算机模型，以估计由于该湖而损失了多少额外的冰，未来将如何变化，以及该湖的存在将在多大程度上改变冰川在21世纪的总体冰损失。这些信息将帮助我们了解世界各地冰川在未来几十年的变化速度，这将有助于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。除了科学目标之外，该项目还将通过与本科项目合作开发计算研讨会并扩大在地球科学界的代表性来加强STEM劳动力。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 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 two different programs in Alaska 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.