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范围的风、潮汐和太阳强迫，但热量和海流的最终分布取决于这些能量如何从大范围的运动转移到小范围的运动，在那里它被耗散。海洋表面被风强迫的一些能量通过密度起伏逃逸到内陆，这种起伏被称为近惯性波，跨度可达数百公里。波浪的另一个重要能源来自潮汐，当它遇到地形并产生内波时，被称为内潮。一般认为，这两类波在其他流动特征的催化下相互作用，并通过内部波场将能量转移到较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以及预测的搅动结果对内波频谱进行参数化，从而产生这些估计的第一张全球地图。这些搅动过程的参数化将有利于大规模海洋大气环流模式(OGCM)，而对内波能量级联及其对垂直混合和耗散的影响的深入理解和参数化将有利于气候模式。认识到同一次会议上的次中尺度、全球海洋监测系统和气候模型人员往往不参加相同的科学会议，研究人员将在2024年海洋科学会议上组织一次联席会议，重点讨论全球模式中的内波和次中尺度参数，从而使这两个群体走到一起。一名研究生将在该项目(UMassD)下接受培训。该小组的持续努力表明了他们对教育、外联、多样性和包容性的承诺。除其他外，Pi Sundermeyer目前为五名女研究生提供咨询，并将寻求在该项目下招收女性和/或任职人数不足/少数族裔的学生。皮桑德迈尔曾在马萨诸塞州桑威奇市公立学区的多个班级做过几次关于海洋过程的演讲。根据目前的项目，他和这名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早期在NSF-REU项目中帮助设计和指导，并共同创建了NWRA早期科学家指导计划；Pi Wortham是西雅图太平洋科学中心的科学交流研究员；PiLelong是MPOWIR的导师，并活跃在SWMS的西雅图分会。NWRA每年夏天都会参加探索队，这是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。这项提议涉及与OGCM模型师H.Simmons和墨西哥数学家G.Hernandez-Duenas的合作。海洋分层内部的内部波场主要从风和潮汐中获取能量，而地转运动和地形散射起到了催化剂的作用。这种能量级联到很小的尺度上，直接搅拌流体，沿途产生涡流模式，然后本身就有助于能量转移和搅拌。尽管观测显示在O(10)公里尺度上的搅拌速度为O(1)m2 S−1，但我们直接从能量源预测这些尺度上的扩散系数的能力仍然存在差距。这项研究的第一个主要贡献将是澄清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，它将把以前关于内波和涡旋模式的搅拌的理论和数值估计推广到更现实的条件。通过考虑现实的层结和强迫，这项研究将填补我们在理解海洋内波场和涡旋模式场如何形成以及这些过程如何在次中尺度上搅动流体方面的一个重大空白。这项工作还将通过量化从各种大尺度强迫中提取能量的速率，并通过内部波场向下级联，来帮助关闭海洋的能量收支。最后，它将量化作为这一级联的一部分自然产生的涡流模场的形状和大小，这一结果在很大程度上仍然难以从现场观察中获得。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 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.