Quantification of energy cascade of internal gravity waves with varying spectral slopes

海洋中的垂直密度差异支持具有不同周期的“内部”波（海洋内部的波）。这些内波的能量通常会逐渐下降到较小的波，最终消散，这一过程被称为能量级联。级联过程可以导致混合，并决定海洋的热量和盐份平衡以及大气环流。该项目将通过理论，建模和数据分析来研究这种能量级联。现有的能量级联的理论，根据内波产生的湍流，将在这项研究中得到改进（解决现有的争议），并扩展到更现实的情况。随后将用高分辨率区域模式模拟对改进的理论进行验证。该项目还将把这一改进的理论应用于全球模型模拟，并建立一个地理耗散图。更广泛的影响包括增强全球气候模型和区域模型。理论上的改进将为内波湍流的一系列物理应用和数学研究提供信息。计划为湍流社区举办年度报告会。这项工作支持早期职业PI，博士后，并通过在加纳的沿海海洋环境暑期学校的教学和公众宣传，并通过在自然历史UM博物馆的程序在流体力学的历史上的公开讲座。拟议的项目将建立一个全面的了解IGW光谱的降尺度能量级联与可变的光谱斜率，从理论和计算的考虑。研究任务包括：1）在波动湍流理论框架内，发展了具有变化斜率的谱的能量级联的理论公式，这将通过动力学方程的模拟来指导和确认。2)进一步改进北纬24-32度、东经193-199度的区域MITgcm模拟，以更好地匹配McLane剖面仪测量的光谱（通过调整模型分辨率和K剖面参数化），计算模拟的能量级联，并与任务1获得的理论结果进行比较。3)应用传统/新的精细尺度参数化的全球MITgcm模式，建立一个地理图的湍流耗散率，和比较的结果，从微观结构测量。新的细尺度参数化公式，从光谱，更紧密地匹配光谱测量，以及改进的区域模型，通过调整K-剖面参数化，将导致从根本上改善diapycnal混合参数化在海洋models.This奖项反映了NSF的法定使命，并已被认为是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的支持。

Vertical density differences in the ocean support 'internal' waves (waves in the ocean's interior) that have different periods. The energy of these internal waves often trickles down to smaller waves that eventually dissipate, a process known as the energy cascade. The cascade process can lead to mixing, and determines the heat and salt balances and general circulation of the ocean. This project will investigate this energy cascade through theory, modeling, and data analysis. The existing theory of the energy cascade, based on the turbulence produced by internal waves, will be improved in this study (with existing controversies resolved) and extended to more realistic situations. Subsequent validation of the improved theory will be done with high-resolution regional model simulations. The project will also apply this improved theory to a global model simulation and establish a geographic map of dissipation . Broader impacts include enhancements to global climate models and regional models. The theoretical improvement will inform a range of physical applications and mathematical studies of internal wave turbulence. Annual presentations are planned for the turbulence community. The work supports an early career PI, a postdoc, and teaching and public outreach through the Coastal Ocean Environment Summer School in Ghana and public lectures on the history of fluid mechanics through programs at the UM Museum of Natural History.The proposed project will establish a comprehensive understanding of the downscale energy cascade of IGW spectra with variable spectral slopes, from both theoretical and computational considerations. Research tasks include: 1) Development of theoretical formulations of energy cascade for spectra with varying slopes in the wave turbulence theory framework, which will be guided and confirmed by simulations of the kinetic equation. 2) Further improvement of the regional MITgcm simulation of 24-32 degrees N, 193-199 degrees E to better match the spectra from McLane profiler measurements (through adjustment of model resolution and K-profile parameterization), computation of the modeled energy cascade with comparison to theoretical results obtained from task 1. 3) Application of the traditional/new finescale parameterization to a global MITgcm model to establish a geographic map of turbulent dissipation rate, and comparison of the results to those from microstructure measurements. The new finescale parameterization formulation from spectra that more closely match spectra from measurements, together with improved regional models through tuning of K-profile parameterization, will lead to fundamentally improved diapycnal mixing parameterizations in ocean models.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.