CAREER: Circumpolar Variability and Exchanges Across the Antarctic Slope Front

南极坡锋几乎完全包围了南极大陆，将相对寒冷的大陆架水域与开放海洋中深度的温暖水域分开。它是侵入南极大陆架的水的“守门人”，比如温暖的环极深水，它为南极洲冰架的底部提供热量，以及从大陆架流出的水，比如密集的水流出，填满了全球三分之一以上的地下海洋。将进行一系列高分辨率海洋数值模拟，以评估过去和正在进行的区域模式和观测活动是否捕获了向大陆的热输送的“热点”，并确定必须解决哪些小尺度/高频过程才能捕获这种热输送。教育部分将通过结合实地考察和以研究为基础的练习，大大扩大大学生对海洋学的参与，与传统教学方法相比，这些练习已被证明可以提高学生的学习和记忆力。这项教育计划每年将吸引数百名本科生到当地的大陆架和加利福尼亚海岸外的斜坡进行研究巡航。一名船长/技术人员将被招募，每年使用加州大学洛杉矶分校的Zodiac科考船进行数十次巡航。项目调查员将编制组织和教育材料，以支持研究巡航，并指导学生形成自己的研究假设，并使用科学计算工具分析自己的数据。在项目结束时，这个教育项目将实现自我维持，从课程费用、研究/教育补助金、捐赠和加州大学洛杉矶分校的直接支持中获得资金。该项目还将为一名研究生提供研究培训，并为一名早期职业教师提供支持。南极气候和小尺度变率所造成的实际限制限制了以往对跨坡交换过程的量化，使其局限于局部区域。在了解开放海洋和大陆架海之间的大陆尺度水交换如何受到大气条件的季节性变化、非均匀测深和小尺度/高频变化源（如涡流、潮汐、溢流和地形波）的调节方面，仍然存在很大的差距。项目研究者建议通过开发第一个海洋/海冰模型模拟整个南极边缘，包括浮动冰架下的海洋，来解决这一理解上的差距，这可以解决小尺度的变化和潮汐。利用基于多重时间尺度分离的分析技术，质量和性质的跨坡交换将被量化，从而确定南极坡锋作为“屏障”和“混合”的机制。然后，同样的框架将用于诊断南极斜坡流的动力学，例如能量和涡度预算，以区分大气强迫、水深导向和小尺度变化在确定南极斜坡锋局部交换中的相对作用。最后，将构建理想过程模型，以探索从环南极模式模拟中得出的具体假设。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。

The Antarctic Slope Front almost completely encircles the Antarctic continent, separating relatively cold shelf waters from warmer waters at mid-depth in the open ocean. It serves as a ``gatekeeper'' for waters intruding onto the Antarctic continental shelf, such as the warm Circumpolar Deep Water that supplies heat to melt the bases of Antarctica's ice shelves, and for waters escaping the continental shelf, such as the dense water outflows that fill more than one-third of the global sub-surface ocean. A series of high-resolution numerical ocean simulations will be conducted to assess whether past and ongoing regional models and observational campaigns are capturing the ``hot spots'' of heat transport toward the continent, and identify which small-scale/high-frequency processes must be resolved to capture this heat transport. The educational component will substantially broaden participation of undergraduates in oceanography by combining field trips and research-based exercises which have been shown to increase student learning and retention compared to conventional teaching methods. The educational initiative will engage hundreds of undergraduate students per year in research cruises to the local continental shelf and slope off the coast of California. A captain/technician will be recruited to facilitate dozens of cruises annually using the UCLA Zodiac research vessel. The project investigator will develop organizational and educational materials to support the research cruises, with students guided to form their own research hypotheses and analyzing their own data using scientific computing tools. By the end of the project period this educational program will become self-sustaining, drawing from a combination of course fees, research/education grants, donations and direct support from UCLA. The project will also provide research training for a graduate student and support for an early-career faculty member.Practical constraints imposed by Antarctica's climate and the small scales of variability have limited previous quantification of cross-slope exchange processes to localized regions. There remains a substantial gap in understanding how continental-scale exchanges of water between the open ocean and the shelf seas are modulated by seasonal variability in atmospheric conditions, hetereogenous bathymetry, and small-scale/high-frequency sources of variability such as eddies, tides, overflows and topographic waves. The project investigator proposes to close this gap in understanding by developing the first ocean/sea ice model simulations of the entire Antarctic margins, including the ocean beneath the floating ice shelves, that can resolve small-scale variability and tides. Using analysis techniques based on multiple separation of time scales, the cross-slope exchanges of mass and properties will be quantified and thereby identify regimes in which the Antarctic Slope Front serves as a ``barrier'' vs. a ``blender''. The same framework will then be used to diagnose the dynamics of the Antarctic Slope Current, for example the energy and vorticity budgets, to distinguish the relative roles of atmospheric forcing, bathymetric steering and small-scale variability in localizing exchanges across the Antarctic Slope Front. Finally, idealized process models will be constructed to explore specific hypotheses derived from the circum-Antarctic model simulation.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.