Collaborative Research: Sediment and Stability: Quantifying the Effect of Moraine Building on Greenland Tidewater Glaciers

格陵兰冰盖（GrIS）目前是海平面上升的最大贡献者，最近超过了高山冰川和冰盖，南极冰盖和陆地水储存的贡献。质量损失集中在冰盖的边缘，低洼的出口冰川流入格陵兰周围的温暖海洋。尽管整体质量损失，格陵兰冰盖的出口冰川经历了显着的变化，在卫星时代观察到的冰川退缩量。这种变化仍然无法解释，因为有许多过程可以影响出口冰川前部的位置，而这些环境很难获得观测结果。该项目旨在收集格陵兰三个出口冰川前端的观测数据，在那里观察到退缩的变化。该项目的目标是确定是否沉积物在冰-海边界是负责观察到的变化冰川退缩。此外，该项目还将测量活动冰川前沿的沉积过程的速率和类型以及卫星记录中观测到的每一冰川过去的位置。该项目还将观测可能导致冰川之间沉积速率变化的基本冰川参数，其总体目标是通过关注该系统中一个了解甚少、观测有限的部分：沉积物收支，了解冰盖变化和稳定性的基本驱动因素。冰川末端的冰碛形成可能使稳定状态的冰川比没有沉积物的情况下更大，这在高融水环境中是显而易见的（例如，阿拉斯加）。然而，冰前沉积的过程和速率知之甚少，特别是在格陵兰岛，那里有丰富的冰碛堤，但在那里，银行的形成对冰盖动力学的影响是不受约束的。该项目的中心假设是，冰碛滩沉积可以稳定或延迟一些冰川系统的退缩。该项目将通过观察四个过程来验证这一假设，这些过程有助于格陵兰岛三个相邻冰川的冰碛形成，这些冰川具有截然不同的动态历史和几何形状。该项目将部署一种新型遥控潜水器（Nereid），用于在深海冰缘环境中进行勘测和取样，以获得冰-沉积物-海洋界面的高分辨率地质、地球物理和海洋学测量结果。该项目将培养研究生，重点是指导和多样化的地球科学。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

The Greenland Ice Sheet (GrIS) is presently the largest contributor of added mass to rising sea levels, recently surpassing contributions from alpine glaciers and ice caps, the Antarctic Ice Sheet and land water storage. Mass loss is concentrated at the periphery of the ice sheet where low-lying outlet glaciers drain into the warm ocean surrounding Greenland. Despite overall mass loss, outlet glaciers of the Greenland Ice Sheet have experienced significant variability in the amount of glacier-front retreat observed over the satellite era. This variability remains unexplained because there are many processes that can influence the position of the front of an outlet glacier and these environments are difficult to obtain observations in. This project aims to collect observations from the front of three outlet glaciers in Greenland where retreat variability has been observed. The goal of this project is to determine if the deposition of sediment at the ice-ocean boundary is responsible for the observed variability in glacier retreat. Further, this project will measure the rates and types of sedimentation processes present at the active glacier front as well as the past position of each glacier observed in the satellite record. The project will also take observations of basic glacier parameters that may be responsible for variations in the rates of sedimentation between glaciers.The overarching goal of this project is to understand the fundamental drivers of ice sheet change and stability through focusing on a poorly understood, observation-limited part of the system: the sediment budget. Moraine building at glacier termini may enable larger steady-state glaciers than would be possible in the absence of sediment, as is evident in high-meltwater settings (e.g., Alaska). However, processes and rates of proglacial sedimentation are poorly known, especially in Greenland, where morainal banks are abundant but where the influence of bank formation on ice sheet dynamics is unconstrained. The central hypothesis of this project is that morainal bank sedimentation can stabilize or delay retreat for some glacier systems. This project will test this hypothesis with observations of four processes that contribute to moraine building at three neighboring Greenland glaciers with sharply different dynamic histories and geometries. The project will deploy a novel remotely operated vehicle (ROV Nereid) designed for surveying and sampling in deep, ice marginal environments to obtain high-resolution geological, geophysical, and oceanographic measurements at the ice-sediment-ocean interface. This project will train graduate students, with a focus on mentorship and diversifying the geosciences.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.