Collaborative Research: Global estimates of energy pathways and stirring by internal waves and vortical mode

海洋的能量主要来自大尺度的风、潮汐和太阳作用，但热量和洋流的最终分布取决于这些能量如何从大尺度运动转移到小尺度运动，并在小尺度运动中消散。海洋表面的风所产生的一些能量通过密度波动（称为近惯性波）逃逸到海洋内部，这种波动可以跨越数百公里。波浪的另一个重要能量来源是潮汐遇到地形时产生的内波，称为内潮。众所周知，这两种类型的波相互作用，在其他流动特征的催化下，通过内波场将能量转移到更小尺度的运动和混合中。这项研究将根据大尺度强迫和其他催化剂参数化内波的频谱，以及预测的搅拌结果，产生这些估计的第一个全球地图。这些搅拌过程的参数化将有利于大尺度海洋环流模式（ogcm），而对内波能级联及其对垂直混合和消散的影响的精确理解和参数化将有利于气候模式。认识到亚中尺度、OGCM和气候建模者在同一次会议上经常不参加相同的科学会议，研究人员将通过在2024年海洋科学会议上组织一次联合会议，将这两个社区聚集在一起，重点讨论全球模式中的内波和亚中尺度参数化。该项目将培养一名研究生（UMassD）。团队的持续努力表明了他们对教育、推广、多样性和包容性的承诺。PI Sundermeyer目前为五名女研究生提供建议（其中包括），并将在该项目下寻求招募女性和/或代表性不足/少数民族学生。PI Sundermeyer在马萨诸塞州桑德威奇公立学区的多个班级做了几次关于海洋过程的演讲。在目前的项目中，他和研究生将与桑威奇和新贝德福德公立学校的初中和高中教师合作，开发与海洋相关的学习模块。PI Early帮助设计和指导了NSF-REU项目，并共同创立了NWRA早期科学家指导项目；PI Wortham是西雅图太平洋科学中心的科学传播研究员；PI Lelong是MPOWIR的导师，活跃于SWMS西雅图分会。每年夏天，NWRA都会参加太平洋科学中心为来自代表性不足社区的高中生和大学生举办的暑期研究项目“探索队”。该提案涉及与OGCM建模师H. Simmons和墨西哥数学家G. Hernandez-Duenas的合作。海洋内部分层的内部波场主要从风和潮汐中获取能量，地转运动和地形散射起到催化剂的作用。这种能量级联到小尺度上，直接搅拌流体，沿途产生涡旋模式，然后它本身有助于能量转移和搅拌。虽然观测表明在0 (10)km尺度上的搅拌速率为0 (1)m2 s−1，但我们在直接从能量来源预测这些尺度上的扩散率方面仍然存在差距。本研究的第一个主要贡献将是阐明相关过程在确定内波和涡旋谱的形状和强度方面的作用。其次，它将扩展以前的理论和数值估计的搅拌从内波和旋涡模式到更现实的条件。通过考虑现实的分层和强迫，本研究将填补我们对海洋内波和涡旋模式场如何形成以及这些过程如何在亚中尺度上搅拌流体的理解的重要空白。这里的工作还将通过量化从各种大尺度强迫中提取能量的速率，并通过内波场进行低尺度级联，从而帮助关闭海洋的能量预算。最后，它将量化作为级联的一部分自然产生的旋涡模式场的形状和大小，这一结果在很大程度上仍然难以从现场观测中获得。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 ocean primarily derives its energy from large-scale wind, tidal and solar forcing, but the ultimate distribution of heat and currents depends on how this energy is transferred from large-scale motions to small scales where it is dissipated. Some of the energy forced by winds at the ocean surface escapes to the interior through density undulations, called near-inertial waves, that can span hundreds of kilometers. Another significant energy source for waves comes from the tide when it encounters topography and produces internal waves, known as the internal tide. It is generally well understood that these two types of waves interact, catalyzed by other flow features, and transfer energy through an internal wave field into smaller scale motions and mixing. This study will parameterize the spectrum of internal waves in terms of the large-scale forcing and other catalysts, and the predicted stirring that results, producing the first global maps of these estimates. Parameterizations of these stirring processes will benefit large-scale ocean general circulation models (OGCMs), and a refined understanding and parameterization of the internal wave energy cascade and its implications for vertical mixing and dissipation will benefit climate models. Recognizing that submesoscale, OGCM and climate modelers at the same meeting often do not attend the same scientific sessions, the investigators will bring these two communities together by organizing a joint session at the 2024 Ocean Sciences meeting, focused on internal wave and submesoscale parameterizations in global models. One graduate student will be trained under this project (UMassD). The ongoing efforts of the team demonstrates their commitment to education, outreach, diversity and inclusion. PI Sundermeyer currently advises (among others) five women graduate students, and will seek to recruit women and/or under- represented/minority students under this project. PI Sundermeyer has given several presentations on ocean processes to multiple classes in the Sandwich, MA public school district. Under the present project, he and the graduate student will work with middle and high school teachers in Sandwich and New Bedford public schools to develop ocean-related learning modules. PI Early helped design and mentor in an NSF-REU program and co-founded the NWRA early-scientist mentoring program; PI Wortham is a Science Communication Fellow at Seattle Pacific Science Center; PI Lelong is a mentor with MPOWIR and active in the Seattle Chapter of SWMS. NWRA participates every summer in Discovery Corps, the Pacific Science Center’s summer research program for high school and college students from under-represented communities. This proposal involves collaborations with OGCM modeler H. Simmons and with Mexican mathematician G. Hernandez-Duenas. The internal wave field in the stratified interior of the ocean draws its energy primarily from winds and tides, with geostrophic motions and topographic scattering acting as catalysts. This energy cascades to small scales and directly stirs the fluid, generating vortical mode along the way, which then itself contributes to energy transfers and stirring. Although observations indicate stirring rates of O(1) m2 s−1 at scales of O(10) km, gaps remain in our ability to predict diffusivity at these scales directly from the energy sources. The first major contribution of this study will be to clarify the roles of relevant processes in setting the shape and strength of the internal wave and vortical spectra. Second, it will extend previous theoretical and numerical estimates of stirring from internal waves and vortical mode to more realistic conditions. By considering realistic stratification and forcing, this study will close a significant gap in our understanding of how the oceanic internal wave and vortical mode fields are formed, and how these processes stir fluid at the submesoscale. The work here will also help close the energy budget for the ocean by quantifying the rate at which energy is extracted from various large-scale forcing, and cascaded downscale through the internal wave field. Last, it will quantify the shape and magnitude of the vortical mode field that arises naturally as part of this cascade, a result that has remained largely elusive from field observations.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.