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

全球内潮汐是具有多种潮汐频率、潮汐方向和潮汐模式的波的叠加。为了充分理解内潮，有必要将其复杂的波场分解成一系列更简单的单色平面波。首席研究员开发了一种波分解技术，适用于卫星海面高度(测高)数据和数值模拟数据，从而能够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这项技术，并将其应用于覆盖全球海洋的卫星测高。结果将用于构建全球内波潮汐分量地图，估计其季节和年际变化及其对海洋混合的贡献。将利用现场测量和数值模拟的现有数据来评估卫星观测的分解内潮汐的准确性。这一研究成果将对野外实验设计和内潮模拟有一定的参考价值。此外，它还将有助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、珊瑚礁漂白、海洋混合等)。将创建一系列内潮产品的动画，并通过YouTube与公众分享。一些动画也将被用来教孩子们关于海洋和卫星技术的知识。这个项目将支持华盛顿大学的一名全日制研究生。内潮在世界海洋中普遍存在，但由于缺乏足够的空间和时间分辨率的现场观测，对内潮的了解仍然很少。卫星测高是在全球范围内观测内潮的唯一实用技术。先前开发的一种既适用于卫星高度计数据又适用于数值模拟的技术，能够将给定的内部潮汐场分解为多模多向波，将进一步在全球范围内推广和应用，其目的是：(1)根据卫星测高建立1-3模M2、S2、O1和K1内潮的全球地图；(2)量化其季节和年际变化；(3)计算沿波束的衰减率和由内潮引起的海洋混合。新的全球内潮模型将由不同频率、不同斜压模式和不同水平传播方向的独立分解波组成。卫星观测到的内潮将根据现场观测和MITgcm全球环流模式模拟进行验证。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 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.