CAREER: Circumpolar Variability and Exchanges Across the Antarctic Slope Front

职业：南极坡锋的绕极变率和交换

• 批准号: 1751386
• 负责人: Andrew Stewart
• 金额: $ 94.59万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1751386&HistoricalAwards=false
• 关键词: CAREER; Circumpolar; Variability; Exchanges; Across

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.

南极斜坡锋几乎完全环绕南极大陆，在开阔海洋中深处将相对寒冷的陆架沃茨与温暖的沃茨分开。它是侵入南极大陆架的沃茨的"守门人“，例如温暖的环极深水，它提供热量融化南极洲冰架的底部，以及逃离大陆架的沃茨，例如充满全球地下海洋三分之一以上的密集水流。将进行一系列高分辨率数值海洋模拟，以评估过去和正在进行的区域模型和观测活动是否捕捉到向大陆输送热量的“热点”，并确定必须解决哪些小规模/高频过程才能捕捉到这种热量输送。教育部分将通过结合实地考察和研究练习，大大扩大本科生对海洋学的参与，与传统教学方法相比，这已被证明可以增加学生的学习和保留。这项教育计划每年将吸引数百名本科生参加到加州海岸附近的当地大陆架和斜坡的研究巡航。将招募一名船长/技术人员，以促进每年使用加州大学洛杉矶分校黄道带研究船数十次巡航。项目研究人员将开发组织和教育材料，以支持研究巡航，引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。到项目结束时，这个教育计划将成为自我维持，从课程费，研究/教育赠款，捐赠和加州大学洛杉矶分校的直接支持相结合的图纸。该项目还将为一名研究生提供研究培训，并为一名职业初期的教员提供支助。南极洲气候和小尺度的变化所造成的实际限制，限制了以前对局部区域的跨坡交换过程的量化。对于大气条件的季节性变化、异源水深测量以及涡旋、潮汐等小规模/高频变化源如何调节公海和陆海之间大陆规模的水交换，人们的理解仍然存在很大差距。溢出和地形波。项目研究人员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，可以解决小规模的变化和潮汐，来缩小这一认识上的差距。将利用以时间尺度多重分离为基础的分析技术，对跨斜坡的质量和性质交换进行量化，从而确定南极斜坡锋作为“屏障”和“混合器”的状况。然后，将使用同一框架来诊断南极斜坡流的动态，例如能量和涡度收支，以区分大气强迫、测深转向和小规模变异在确定南极斜坡锋交换的局部化方面的相对作用。最后，将建立理想化的过程模型，以探索从环南极模型模拟中得出的具体假设。该奖项反映了NSF的法定使命，并被认为值得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来支持。

项目成果

Boundary layer-mediated vorticity generation in currents over sloping bathymetry

• DOI: 10.1175/jpo-d-20-0253.1
• 发表时间: 2021-03
• 期刊: Journal of Physical Oceanography
• 影响因子: 3.5
• 作者: Arjun Jagannathan;K. Srinivasan;J. McWilliams;M. Molemaker;A. Stewart

Dynamics of Eddies Generated by Sea Ice Leads

• DOI: 10.1175/jpo-d-20-0169.1
• 发表时间: 2021-07
• 期刊: Journal of Physical Oceanography
• 影响因子: 3.5
• 作者: K. Cohanim;Ken Zhao;A. Stewart

“Eddy” Saturation of the Antarctic Circumpolar Current by Standing Waves

– 涡流 – 驻波使南极绕极流饱和

• DOI: 10.1175/jpo-d-22-0154.1
• 发表时间: 2023
• 期刊: Journal of Physical Oceanography
• 影响因子: 3.5
• 作者: Stewart, Andrew L.;Neumann, Nicole K.;Solodoch, Aviv
• 通讯作者: Solodoch, Aviv

Stirring of interior potential vorticity gradients as a formation mechanism for large subsurface-intensified eddies in the Beaufort Gyre

内部位涡梯度的搅拌作为波弗特环流中大型地下强化涡的形成机制

• DOI: 10.1175/jpo-d-21-0040.1
• 发表时间: 2022
• 期刊: Journal of Physical Oceanography
• 影响因子: 3.5
• 作者: Manucharyan, Georgy E.;Stewart, Andrew L.
• 通讯作者: Stewart, Andrew L.

Mid-Holocene Northern Hemisphere warming driven by Arctic amplification

• DOI: 10.1126/sciadv.aax8203
• 发表时间: 2019-12
• 期刊: Science Advances
• 影响因子: 13.6
• 作者: Hyo‐Seok Park;Seong‐Joong Kim;A. Stewart;S. Son;K. Seo