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数据，以研究由此产生的热和盐的扩散如何改变进入陆架的水的性质。环极深水(CDW)在暗流中通过松岛Thwaites West海槽进入阿蒙森海架，并向不断缩小的松岛和Thwaites冰盖移动。国家海洋研究中心资助的一个现有项目，题为“阿蒙森海海洋变化的驱动因素”(数十年)，计划在季节性时间尺度上探索大陆架上的热量输送；这项工作将利用几十年的船舶时间，以通过海槽的高频热量输送为目标。目标是：1)在几十年内扩大观测能力，以直接测量CDW进入低谷时的转变；2)了解推动转变的过程；以及3)研究潜流转变为低谷的可能机制。这项工作将有助于更好地理解推动冰盖融化的过程，这可能会改进海平面上升的建模和预测。在这个数据稀少的区域进行新的湍流测量将有助于完善新出现的湍流数据处理标准。该提案支持一名早期职业调查员，并包括两个教育和外展部分：数据将为一名暑期实习生和一名“书呆子规则海洋大使”提供基础项目。PIS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岁的年轻人接触到专注于海洋和气候正义的社区教育和指导机会。将使用最先进的高分辨率船载仪器：“FastCTD”(5米/S下降率，额定下降率为2000米，剖面可每20分钟测量一次)和定制的“EpsiFish”(一种松散连接的自由落体微结构湍流剖面仪，带有泵送的CTD、剪切探头和快速响应热敏电阻)。除了5个计划中的数十年系泊外，还有三个剖面系泊--两个越冬系泊和一个在船上观测期间额外测量的湍流。船基工作将在2024年初(南夏)进行，湍流系泊设备将于同年夏天部署并恢复，其他两个系泊设备将于2025年初恢复，数十年的系泊设备也将恢复。这些测量得到的速度和温度微结构数据将分别用于计算湍流动能和热方差的耗散率。耗散率是使用标准技术从剪切探头数据计算得出的，该技术涉及将观测到的湍流惯性子区的剪切谱拟合成标准谱形状。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。

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.