INTeRnal waves In angular momeNtum StratifICation (INTRINSIC)

该项目将使用简化模型和数值模型来研究具有弯曲形状的水密度的“快速”变化，即“弯曲前沿”，如何修改海洋表面边界层内内部重力波（IGW）的传播和命运。研究人员将确定IGW能量是否在弯曲的精细尺度锋内增加或减少。他们将测试一个新的假设，即参数亚谐不稳定性，最初由托马斯和泰勒（2014）提出的地转流，在弯曲的反气旋锋内升高。该研究使用了一个层次的精细尺度模拟，从而分析和理想化的数值模型（最不复杂），以告知和促进现实的模拟（最复杂）的分析。目前的理解IGW的传播内锋假设一个地转平衡。虽然对中尺度锋面（水平尺度为50-200公里）是准确的，但由于锋面曲率，次中尺度锋面（水平尺度为0.1-10公里）内的流体包往往经历明显的向心加速。密度、涡量和绝对角动量守恒的组合原理对流体包裹体运动有着深远的影响，并修改了IGW色散关系。拟议中的研究推进了科学界的IGWs的理解，通过检查这些守恒定律的半分析，理想化和现实的精细尺度，数值模拟的背景下，大量的观测信息的综合影响。这项研究的预期成果包括加深对弯曲锋对IGW动力学作用的理解，以及划定分析模型的局限性。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的评估被认为值得支持影响审查标准。

This project will use a simplified model and a numerical model to examine how a 'rapid' change in water density that has a curved shape, a 'curved front', modifies the propagation and fate of internal gravity waves (IGW) within the ocean surface boundary layer. The investigators will determine if IGW energy increases or decreases within fine-scale fronts that are curved. They will test a new hypothesis that parametric subharmonic instability, initially proposed by Thomas and Taylor (2014) for geostrophic flow, is elevated within curved anticyclonic fronts. The research uses a hierarchy of fine-scale simulations, whereby analytical and idealized numerical models (least complex) are used to inform and facilitate analysis of realistic simulations (most complex).Present understanding of IGW propagation within fronts assumes a geostrophic balance. Although accurate for mesoscale fronts (horizontal scales of 50-200 km), fluid parcels within submesoscale fronts (horizontal scales of 0.1-10 km) often experience pronounced centripetal accelerations owing to frontal curvature. The combined principles of density, vorticity, and absolute angular momentum conservation have a profound influence on fluid parcel motion and modify the IGW dispersion relation. The proposed study advances the scientific community’s understanding of IGWs by examining the combined effects of these conservation laws in the context of semi-analytical, idealized and realistic fine-scale, numerical simulations heavily informed by observations. The expected outcomes of this research include improved understanding of the role of curved fronts on IGW dynamics and delineation of the limits of an analytical model.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.