Global Internal Tide Model from Satellite Altimetry by Resolving Multiconstituent Multimodal Multidirectional Waves

全球内部潮汐场是具有多个潮汐频率、方向和模态的波浪的叠加。为了充分认识内潮，有必要将其复杂的波场分解为一系列较简单的单色平面波。首席研究员开发了一种波分解技术，适用于卫星海面高程（测高）数据和数值模拟数据，可以发现隐藏在原始内波场中的前所未有的特征。该项目将进一步发展该技术，并将其应用于覆盖全球海洋的卫星测高。这些结果将用于构建内波潮汐分量的全球地图，提供它们的季节和年际变化及其对海洋混合的贡献的估计。卫星观测到的分解的内部潮汐的准确性将利用来自实地测量和数值模拟的现有数据进行评估。本文的研究成果将为内潮的野外实验设计和模拟提供参考。此外，它将有利于研究受内部潮汐影响的其他海洋过程（如初级生产力、海洋声学、珊瑚礁白化、海洋混合等）。将制作一系列内部潮汐产品的动画，并通过YouTube分享给公众。其中一些动画还将用于教授孩子们有关海洋和卫星技术的知识。该项目将资助华盛顿大学的一名全日制研究生。内部潮汐在世界海洋中普遍存在，但由于缺乏具有足够空间和时间分辨率的实地观测，人们对内部潮汐的了解仍然很少。卫星测高是在全球范围内观测内部潮汐的唯一实用技术。一项既适用于卫星高度计数据又适用于数值模拟的、能够将给定的内部潮汐场分解为多模态多向波的技术将在全球范围内进一步扩展和应用，目的是：(1)利用卫星高度计构建mode-1-3 M2、S2、O1和K1内部潮汐的全球地图；(2)量化它们的季节和年际变化；(3)计算沿梁衰减率和内部潮汐驱动的海洋混合。新的全球内潮模式将由不同频率、不同斜压模态和不同水平传播方向的独立解析波组成。卫星观测到的内部潮汐将与原位观测和MITgcm全球环流模式模拟进行验证。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 global internal tide field is a superposition of waves with multiple tidal frequencies, directions, and modes. To fully understand internal tides, it is necessary to decompose their complex wave field into a series of simpler monochromatic plane waves. The principal investigator has developed a wave decomposition technique suitable for use with data from both satellite sea surface elevation (altimetry) data and numerical simulations that enables the discovery of unprecedented features hidden in the raw internal wave field. This project will further develop the technique and apply it to satellite altimetry covering the global ocean. The results will be used to construct global maps of internal wave tidal components, provide estimates of their seasonal and interannual variability and their contribution to ocean mixing. The accuracy of the satellite observed decomposed internal tides will be evaluated using existing data from field measurements and numerical simulations. The product of this research will be useful for the design of field experiments and modeling of internal tides. In addition, it will benefit research on other ocean processes influenced by internal tides (e.g., primary productivity, ocean acoustics, coral reef bleaching, ocean mixing etc.). A series of animations of internal tide products will be created and shared to the public via YouTube. Some of the animations will also be used to teach children about the ocean and satellite technology. This project will support a full-time graduate student at the University of Washington.Internal tides are ubiquitous in the world oceans but still poorly understood due to the scarcity of field observations with sufficient spatial and temporal resolution. Satellite altimetry is the only practical technique for observing internal tides on the global scale. A previously developed technique applicable to both satellite altimeter data and numerical simulations and capable of decomposing a given internal tide field into multimodal multidirectional waves will be further expanded and applied on a global scale with the aim to: (1) construct global maps of mode-1–3 M2, S2, O1 and K1 internal tides from satellite altimetry; (2) quantify their seasonal and interannual variations; and (3) calculate along-beam decay rates and internal tide driven ocean mixing. The new global internal tide model will consist of separately resolved waves of different frequencies, different baroclinic modes and different horizontal propagation directions. The satellite observed internal tides will be validated against in-situ observations and MITgcm global circulation model simulations.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.