Collaborative Research: Characteristics and Origins of Eddies beneath Antarctic Sea Ice

世界海洋在不断地运动，而这种运动的很大一部分是以涡流的形式出现的，即跨越数十到数百公里的近水平的水的漩涡。这些漩涡通过调节大范围洋流、重新分配热量和向海洋生态系统提供营养物质来影响海洋。因此，海洋科学界历来投入大量精力来描述这些旋涡的性质和影响。在极地地区，海冰覆盖阻碍了对漩涡的观测，而涡旋的水平尺寸相对较小，阻碍了对其行为的计算机模拟。尽管如此，之前的研究已经确定了北冰洋海冰下活跃的涡旋种群，并表明这些涡旋在维持北冰洋大范围环流方面发挥着至关重要的作用。然而，目前还没有系统地研究南极海冰下的涡旋，这给我们对涡旋及其对南极周围大范围海洋环流的贡献的理解留下了很大的空白。将利用Argo浮标和仪器海豹在南极海冰下进行的水文观测，得出海底冰涡状场的统计特征。高分辨率的全球海洋和海冰模式将被用来追踪模拟的涡流回到它们的形成地点，以确定涡流的形成机制。理论计算将被用来检验这样的假设，即涡旋主要源于与地下密度梯度有关的水动力不稳定性。这些理论、模拟和数据分析方法将被结合起来，以估计涡旋对横向示踪剂输送的贡献及其对近南极海洋平均环流的影响。这项拟议的工作将通过提供检测到的涡流特性的公开数据库来促进未来的科学努力。该项目将支持几名初级科学家的研究：一名本科生、两名研究生和一名职业生涯早期的教职员工。该奖项反映了NSF的法定使命，并通过使用基金会的学术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 world ocean is continuously in motion, and a large fraction of this motion takes the form of "eddies", nearly-horizontal swirls of water spanning tens to hundreds of kilometers. These eddies affect the ocean by mediating large-scale currents, redistributing heat, and supplying nutrients to oceanic ecosystems. Consequently, the ocean science community has historically invested substantial effort in characterizing the properties and impact of these eddies. In polar regions, the sea ice cover inhibits observations of eddies, and the relatively small horizontal size of the eddies hampers computer simulations of their behavior. Nonetheless, previous studies have identified an active population of eddies beneath the Arctic sea ice and shown that these eddies play a crucial role in maintaining the large-scale circulation in the Arctic seas. However, there has been no systematic attempt to study such eddies under Antarctic sea ice, leaving a significant gap in our understanding of eddies and their contribution to the large-scale ocean circulation around Antarctica.The proposed research combines multiple approaches to improve our understanding of the eddy dynamics. Statistical characterizations of the sub-sea ice eddy field will be derived using hydrographic observations under Antarctic sea ice from Argo floats and instrumented seals. High-resolution global ocean and sea ice models will be used to track the simulated eddies back to their formation sites to identify the eddy formation mechanisms. Theoretical calculations will be conducted to test the hypothesis that the eddies primarily originate from hydrodynamic instabilities associated with subsurface density gradients. These theoretical, modeling, and data analysis approaches will be combined to estimate the eddies' contribution to lateral tracer transports and their impact on mean circulations of the near-Antarctic ocean. The proposed work will facilitate future scientific endeavors by providing publicly-available databases of detected eddy properties. This project will support the research of several junior scientists: an undergraduate student, two graduate students, and an early-career faculty member.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.