Characterizing the warm water flow through Pine Island Thwaites West Trough

描述流经松岛思韦茨西槽的暖水流特征

• 批准号: 2219941
• 负责人: Nicole Couto
• 金额: $ 171.44万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2219941&HistoricalAwards=false
• 关键词: Characterizing; warm; water; flow; through

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.

该项目将收集阿蒙森海陆架断裂处湍流流体运动的新观测结果，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特性。环极深水 (CDW) 在暗流中通过派恩岛思韦茨西海槽进入阿蒙森海陆架，并流向不断缩小的派恩岛和思韦茨冰盖。 NERC 资助的现有项目名为“阿蒙森海海洋变化的驱动因素”（DECADES），计划探索季节性时间尺度上大陆架的热传输；这项工作将利用数十年的运输时间来瞄准通过槽的高频热传输。目标是：1）在几十年内扩大观测能力，以直接测量车辆碰撞波进入低谷时的转变； 2）了解推动转型的流程； 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驱动冰盖融化的过程，从而改善海平面上升的建模和预测。这个数据稀疏区域的新湍流测量将有助于完善新兴的湍流数据处理标准。该提案支持早期职业调查员，并包括两个教育和外展部分：数据将为暑期实习生和“书呆子规则海洋大使”提供基础项目。 PI 参与海洋大使计划，该计划旨在让来自服务匮乏背景的 10 至 25 岁青少年获得关注海洋和气候正义的社区教育和指导机会。将使用高分辨率船载最先进仪器：“FastCTD”（下降速率为 5 m/s，额定高度为 2000m，每 20 分钟可完成 600m 的剖面）和定制的“Epsifish”（松散系留的自由落体微结构湍流剖面仪，配有泵送 CTD、剪切探针和快速响应热敏电阻）。除了 5 个计划中的 DECADES 系泊设施外，还有 3 个剖面系泊设施 - 2 个用于越冬，1 个用于在船上观测期间额外测量湍流。船基工作将于 2024 年初（澳大利亚夏季）进行，湍流系泊装置于同年夏季部署并恢复，另外两个系泊装置与 DECADES 系泊装置一起于 2025 年初恢复。这些测量所得的速度和温度微观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根据剪切探针数据计算得出的，这些技术涉及将湍流惯性子范围内观察到的剪切光谱拟合到标准光谱形状。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。