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，将开阔海洋中较冷的大陆架水域与较温暖的水域隔开。对于侵入南极大陆架的水域，例如提供热量以融化南极冰架底部的温暖的环极深水，以及对于逃离大陆架的水域，它是一个“把关人”，例如占全球次表层海洋三分之一以上的高密度水外流。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捉到了向大陆输送热量的“热点”，并查明必须解决哪些小尺度/高频过程才能捕捉到这种热量输送。教育部分将通过将实地考察和基于研究的练习结合起来，大大扩大本科生对海洋学的参与，事实证明，与传统的教学方法相比，这些练习可以提高学生的学习和保持能力。这项教育计划每年将吸引数百名本科生参与研究邮轮，前往加州海岸外的当地大陆架和斜坡。将招募一名船长/技术员，每年使用加州大学洛杉矶分校的生肖研究船为数十次巡航提供便利。项目调查员将开发组织和教育材料来支持研究巡航，指导学生形成他们自己的研究假设，并使用科学计算工具分析他们自己的数据。到项目期结束时，这个教育项目将自给自足，包括课程费、研究/教育补助金、捐款和加州大学洛杉矶分校的直接支持。该项目还将为研究生提供研究培训，并为职业生涯早期的教职员工提供支持。南极洲气候施加的实际限制和小范围的可变性将以前对跨坡交换过程的量化限制在局部地区。在理解公海和陆架海之间大陆尺度的水交换如何受到大气条件的季节变化、非均匀水深测量以及小尺度/高频变化来源，如涡旋、潮汐、溢流和地形波的影响方面，仍然存在很大差距。项目调查员提议通过开发第一个能够解决小尺度变率和潮汐的整个南极边缘，包括漂浮冰架下的海洋的海洋/海冰模型模拟来弥合这一认识上的差距。利用基于多个时间尺度分离的分析技术，将量化质量和性质的跨坡交换，从而确定南极坡锋作为“屏障”与“搅拌器”的制度。然后将使用相同的框架来诊断南极坡流的动态，例如能量和涡度收支，以区分大气强迫、测深操纵和小尺度变率在确定南极坡锋的局部交换方面的相对作用。最后，将构建理想化的过程模型，以探索从环南极模型模拟得出的具体假设。这一奖项反映了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。

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.