Submesoscale sea ice-ocean interactions in marginal ice zones

确定控制边缘冰区（MIZ）动态的关键过程仍然是我们理解和准确模拟快速变化的极地海洋的能力的关键挑战之一。混合带是海洋温度和盐度具有强烈混合层梯度的区域，表明在相对较小的空间尺度上海洋的变异性应该会增强。然而，目前缺少对MIZ动态中小尺度流动作用的定量估计，气候模式也没有对这些非线性过程进行参数化。这项研究将检验这样的假设：相对较小尺度的高能垂直速度可以有效地使海洋热量与海冰接触并影响其融化速率。这项研究对于社会了解海冰和海洋环流如何在变化的气候中在修改的表面强迫条件下演变至关重要。该研究活动将通过在几个美国学术机构之间建立跨学科合作，并扩大代表性不足的群体的参与，培养一支多元化和具有全球竞争力的STEM劳动力队伍。该项目将主要资助一名博士后科学家，他将接受物理海洋学和遥感领域的广泛培训。研究人员将通过开展本科生和研究生教学活动、指导暑期本科生和参加高中外联活动，为提高社会对科学和技术的认识做出贡献。该项目将使用一个亚中尺度允许的全球海洋模式，结合一套理想化的数值试验，诊断各种MIZ中的亚中尺度流动特征，分类其生成机制，并评估它们对海冰融化率的累积影响。将通过进行水动力稳定性分析和评估MIZ过程来确定临界强迫，MIZ过程将驱动位涡向次中尺度流的负值特征。将探讨能量收支分析，以了解次中尺度源和汇，并揭示海冰-海洋阻力在抑制海洋上层变率方面的作用。将建立一个解释海冰速度和密集模式的理论框架，并将其与卫星数据一起用于在观测上限制海洋中的亚中尺度垂直速度。该项目实现了高分辨率数值模拟，理论发展和观测数据分析的协同三位一体，代表了一个及时和独特的机会，以改变我们对MIZ中海冰-海洋相互作用的理解。这项研究将导致对次中尺度海冰-海洋热通量进行全球估计，并在卫星对MIZ海冰模式观测的支持下，提供一个理论框架，以确定次中尺度热通量占主导地位的海洋和大气条件。遥感部分将统一来自多个卫星的观测结果，并创建一套新的亚中尺度海洋涡度二维观测结果，可用于直接测试和推进上层海洋湍流理论。完成后，该研究项目将推进我们对亚中尺度海冰海洋相互作用的认识，并揭示缺失的海洋-冰热路径;结果也将改善未来对海冰范围的预测。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。

Identifying critical processes governing marginal ice zone (MIZ) dynamics remains one of the key challenges in our ability to comprehend and accurately model the rapidly changing polar oceans. MIZs are regions of strong mixed layer gradients in ocean temperatures and salinities, indicating that enhanced ocean variability at relatively small spatial scales ought to be present there. However, quantitative estimates of the role of small scale flows in MIZ dynamics are currently missing, and climate models do not parameterize these non-linear processes. This research will test the hypothesis that energetic vertical velocities at relatively small scales can efficiently bring the oceanic heat in contact with the sea ice and affect its melt rates. The research is of critical importance to society for understanding how sea ice and ocean circulation evolve under modified surface forcing conditions in a changing climate. The research activity will develop a diverse and globally competitive STEM workforce by establishing interdisciplinary collaborations among several U.S. academic institutions and broadening participation of underrepresented groups. The project will primarily fund a post-doctoral scientist who will be trained with broad exposure to the fields of physical oceanography and remote sensing. The investigators will contribute to enhancing society's scientific and technological understanding by engaging in undergraduate and graduate teaching activities, mentoring summer undergraduate students and participating in high-school outreach activities.The project will use a submesoscale-permitting global ocean model together with a set of idealized numerical experiments to diagnose the characteristics of submesoscale flows in various MIZs, classify their generation mechanisms, and assess their cumulative impact on sea ice melt rates. Critical forcing will be identified by conducting hydrodynamic stability analysis and by evaluating MIZ processes driving the potential vorticity towards negative values characteristic of sub-mesoscale flows. An energy budget analysis will be explored to understand submesoscale sources and sinks, and reveal the role of sea ice-ocean drag in damping upper-ocean variability. A theoretical framework explaining sea ice velocity and concentration patterns will be developed and used together with satellite data to observationally constrain submesoscale vertical velocities in the ocean. The project implements a synergetic triad of high resolution numerical simulations, theory development, and observational data analysis, representing a timely and unique opportunity to transform our understanding of sea ice-ocean interactions in MIZs. The research will result in a global estimate of submesoscale sea ice-ocean heat fluxes and, supported by satellite observations of sea ice patterns in MIZs, provide a theoretical framework to identify oceanic and atmospheric conditions under which submesoscale heat fluxes prevail. The remote sensing component will unify observations from multiple satellites and create a novel set of two-dimensional observations of ocean vorticity at submesoscales that could be used to directly test and advance upper-ocean turbulence theories. Upon completion, this research project will advance our knowledge of submesoscale sea ice ocean interactions and reveal missing ocean-ice heat pathways; results will also improve future predictions of sea ice extent.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.