Characterizing the warm water flow through Pine Island Thwaites West Trough

该项目将收集阿蒙森海陆架断裂处湍流运动的新观测结果，以研究由此产生的热量和盐的扩散如何改变进入陆架的水的性质。绕极深水（CDW）通过暗流中的松岛斯威茨西槽进入阿蒙森海陆架，并向收缩的松岛和斯威茨冰盖移动。一个由自然资源研究中心资助的题为“阿蒙森海海洋变化的驱动因素”的现有项目计划以季节为时间尺度探索大陆架上的热传输;这项工作将利用“十年”的船期，以通过海槽的高频热传输为目标。目标是：1）扩展DECADES的观测能力，以直接测量CDW进入低谷时的转变; 2）了解推动转变的过程; 3）研究暗流转变为低谷的可能机制。这项工作将有助于更好地了解推动冰盖融化的过程，这可以改善海平面上升的建模和预测。在这个数据稀疏的地区新的湍流测量将有助于完善湍流数据的新兴处理标准。该提案支持早期职业调查员，并包括两个教育和推广部分：数据将为暑期实习生和“书呆子的规则海洋大使”提供基础项目。PI参与了海洋大使计划，该计划旨在让来自服务不足背景的10至25岁的年轻人获得专注于海洋和气候正义的社区教育和指导机会。将使用高分辨率船基最先进的仪器：“FastCTD”（5 m/s下降速率，额定2000 m，每20分钟可完成600 m的剖面）和定制的“Epsifish”（带有泵送CTD、剪切探针和快速响应热敏电阻的松散系留自由下落微结构湍流剖面仪）。三个剖面系泊-两个越冬系泊和一个在船上观测期间额外测量湍流-以及5个计划的DECADES系泊。基于船舶的工作将于2024年初（南夏季）进行，湍流系泊系统将在同一个夏季部署和恢复，另外两个系泊系统将于2025年初沿着DECADES系泊系统恢复。从这些测量的速度和温度微观结构数据将被用来计算湍流动能和热方差的耗散率，分别。耗散率是使用标准技术从剪切探针数据计算出来的，该技术涉及将湍流惯性子范围内观察到的剪切谱拟合到标准谱形状。该奖项反映了NSF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。

This project will collect novel observations of turbulent fluid motions at the Amundsen Sea shelf break to examine how the resulting diffusion of heat and salt changes the properties of water entering the shelf. Circumpolar Deep Water (CDW) enters the Amundsen Sea shelf through the Pine Island Thwaites West Trough within an undercurrent and travels toward the shrinking Pine Island and Thwaites Ice Sheets. An existing NERC-funded project entitled “Drivers of Oceanic Change in the Amundsen Sea” (DECADES) plans to explore heat transport on the shelf at seasonal timescales; this work would utilize DECADES ship time to target high-frequency heat transport through the trough. Goals are to: 1) expand the observational capabilities in DECADES to directly measure transformation of CDW as it enters the trough; 2) understand the processes driving the transformation; and 3) examine possible mechanisms by which the undercurrent turns into the trough. The work would contribute to a better understanding of the processes driving ice sheet melt, which could improve modeling and predictions of sea level rise. New turbulence measurements in this data-sparse region will help refine the emerging processing standards for turbulence data. This proposal supports an early career investigator, and includes two education and outreach components:vthe data will provide basis projects for a summer intern and a “Nerd's Rule Ocean Ambassador.” PIs are involved in the Ocean Ambassador program, which aims to expose 10- to 25-year-olds from underserved backgrounds to community education and mentoring opportunities focused on ocean and climate justice. High-resolution ship-based state of the art instrumentation will be used: the "FastCTD" (5 m/s descent rate, rated to 2000m, profiles to 600m can be done every 20 minutes) and the custom-built "Epsifish" (a loosely tethered free-falling microstructure turbulence profiler with pumped CTD, shear probes, and fast-response thermistors). Three profiling moorings - two overwintering and one additional measuring turbulence during the shipboard observations - in addition to 5 planned DECADES moorings. Ship based work would occur in early 2024 (austral summer) with the turbulence mooring deployed and recovered the same summer, and the other two moorings recovered in early 2025 along with the DECADES moorings. Velocity and temperature microstructure data from these measurements will be used to calculate the dissipation rates of turbulent kinetic energy and thermal variance, respectively. Dissipation rates are calculated from shear probe data using standard techniques that involve fitting observed shear spectra in the inertial sub-range of turbulence to standard spectral shapes.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.