Collaborative Research: Probing internal gravity wave dynamics and dissipation using global observations and numerical simulations

该项目将使用最先进的高分辨率全球和区域内部重力波模型沿着内部重力波的理论和观测，绘制内部重力波（IW）消散和混合的时空地理图，以及潜在的动力学。 该研究将采用全球模型，区域模型，观测和理论，朝着未来迈出第一步，在未来，IW耗散和混合在模型中自然出现，而不被参数化。该项目将支持东非肯尼亚的两所海洋和环境科学暑期学校，以补充自2015年以来每年成功举办的西非暑期学校，主要研究人员假设，全球信息战模型中信息战频谱的表示足够真实，模型可以关于IW耗散的空间和时间分布的有用预测，并通过扩展，IW诱导的混合。他们还假设，正如一个惯性子范围是隐式解决湍流的大涡模拟，隐式解决IW连续模型可能是触手可及的耗散方案，模型分辨率，大气强迫频率，并使非流体静力学的适当选择。将运行区域IW模型，以确定分辨率限制和耗散机制对模拟IW频谱的影响。区域IW模拟和IW理论将用于探测IW频谱和耗散的动力学基础。 耗散将使用四种不同的方法进行映射：作为使用传统的傅立叶技术计算的光谱通量，作为使用新的粗粒度技术计算的光谱通量，作为IW转换率和通量发散的残差，以及从应用于高频流的模型耗散算子计算。模拟的能量耗散率将与基于观测的耗散估计值进行比较，这些耗散来自应用于ARGO浮子和船基CTD线路的精细结构方法，以及微观结构测量，包括来自NSF资助的一套新的EM-APEX浮子的测量。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知识价值和更广泛的影响审查标准进行评估来支持。

This project will map the space-time geography of internal gravity wave (IW) dissipation and mixing, and the underlying dynamics, using state-of-the-art high-resolution global and regional IW models along with theory and observations of IWs. The research will employ global models, regional models, observations, and theory to take a first step towards a future in which IW dissipation and mixing arise naturally in models, without being parameterized. The project will support two summer schools on ocean and environmental science in Kenya, East Africa, to complement the successful West African summer schools that has been run every year since 2015, with cumulative participation of several hundred African participants and several dozen US participants.The Principal Investigators hypothesize that the representation of the IW spectrum in global IW models is sufficiently realistic for the models to make useful predictions about spatial and temporal distributions of IW dissipation and, by extension, IW-induced mixing. They also hypothesize that much as an inertial subrange is implicitly resolved by Large Eddy Simulations of turbulence, an implicitly resolved IW continuum in models may be within reach with appropriate choices of dissipation schemes, model resolutions, atmospheric forcing frequency, and enabling of nonhydrostatic dynamics. Regional IW models will be run to determine the impacts of resolution limitations and dissipation mechanisms on the modeled IW spectrum. Regional IW simulations and IW theory will be used to probe the dynamics underlying the IW spectrum and dissipation. Dissipation will be mapped using four different methods: as spectral fluxes computed using traditional Fourier techniques, as spectral fluxes computed using new coarse-graining techniques, as a residual of IW conversion rates and flux divergences, and as computed from model dissipation operators applied to high-frequency flow. Modeled energy dissipation rates will be compared to observation-based estimates of dissipation, from fine-structure methods applied to ARGO floats and ship-based CTD lines, and from microstructure measurements including those from a new NSF-funded set of EM-APEX floats.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.