Collaborative Research: Surface wave impacts on upper ocean response to tropical cyclones

目前全球天气/气候数值模式的发展正朝着更高的空间分辨率方向发展，因此它们现在能够解决极端天气事件，包括热带气旋。事实上，TC预测模型和全球天气预测模型预计将在不久的将来合并。热带气旋下海洋表层的湍流混合通过海气之间的热量和动量交换有效地耦合了海洋和大气。这种海气耦合受到海洋表面波（海况）的调制，海洋表面波在TC条件下特别复杂和多变。表面波影响海洋上层的一维（垂直混合/扩散）和三维（上升流和水平平流）过程。这项研究的重点是推进海洋湍流混合计划，明确包括表面波的影响。虽然世界各地的建模中心都在进行类似的工作，但这些工作很少包括极端（TC）条件。从这项研究的结果将通知领先的顺序影响，在大风条件下，上层海洋过程中的表面波，耦合波和海洋模型的好处，以及最佳的方法来实现波相关的参数化。拟议的努力是及时的，将立即有利于区域和全球天气和气候建模社区。研究结果将被纳入飓风：科学与社会网站，目前有成千上万的教育工作者和学生以及公众使用。除了技术培训外，研究生还将接受教育和推广专业人员的培训，学习如何将复杂的科学概念转化为非专业语言。这项合作研究将结合最先进的建模和以前实地项目中获得的观测数据进行。具体而言，上层海洋对几个历史热带气旋的响应将使用耦合海浪模型进行模拟，该模型包括海况相关的朗缪尔湍流参数化和其他重要的表面波影响（斯托克斯平流，科里奥利斯托克斯力，斯托克斯剪切力和海气动量通量预算）。首先，模型结果将被用来约束风应力和阻力系数。接下来，模型的结果，有和没有波的影响，将与观测数据，包括混合层温度，电流和湍流数据进行比较。这项调查将澄清是否朗缪尔湍流和其他表面波的影响，使领先的顺序上层海洋的热带气旋的反应，以及是否需要一个完全耦合的海浪模式与海况依赖的参数化准确的预测。这项研究将与NOAA/地球物理流体动力学实验室的科学家密切合作进行，并将有助于NOAA的研究和耦合大气-海洋模型的发展，涉及上层海洋混合对气候和天气预报的作用。

The current development of global weather/climate numerical models is moving in the direction of higher spatial resolutions, such that they are now capable to resolve extreme weather events, including tropical cyclones (TCs). In fact, TC prediction models and global weather prediction models are expected to merge in a near future. Turbulent mixing in the ocean surface layer under TCs effectively couples the ocean and atmosphere through air-sea exchanges of heat and momentum. This air-sea coupling is modulated by ocean surface waves (sea states) that are particularly complex and varied under TC conditions. Surface waves affect both one-dimensional (vertical mixing/diffusion), and three-dimensional (upwelling and horizontal advection) processes in the upper ocean. The focus of this study is to advance ocean turbulent mixing schemes that explicitly include the impact of surface waves. Although similar efforts are underway in modeling centers worldwide, few of such efforts include extreme (TC) conditions. Results from this study will inform on the leading order impacts from surface waves on upper ocean processes in high wind conditions, on the benefits of coupling wave and ocean models, and on optimal approaches to implementing wave-dependent parameterizations. The proposed effort is timely and will immediately benefit both the regional and global weather and climate modeling communities. The results of the research will be integrated into the Hurricanes: Science and Society website that is currently used by tens of thousands of educators and students as well as the general public. In addition to their technical training, the graduate students will receive training from education and outreach professionals on how to translate complex scientific concepts into non-expert language.This collaborative study will be carried out by combining state-of-the-art modeling and observational data obtained in previous field programs. Specifically, upper ocean responses to several historical Tropical Cyclones will be simulated using a coupled ocean-wave model that includes sea-state dependent Langmuir turbulence parameterizations and other significant surface wave impacts (the Stokes advection, the Coriolis Stokes force, the Stokes shear force, and the air-sea momentum flux budget). First, the model results will be used to constrain the wind stress and the drag coefficient. Next, the model results, with and without the wave effects, will be compared with observational data, including mixed layer temperature, current, and turbulence data. This investigation will clarify whether the Langmuir turbulence and other surface wave effects make leading order impacts on upper ocean responses to Tropical Cyclones, and whether their accurate prediction requires a fully coupled ocean-wave model with sea-state dependent parameterizations. This study will be conducted in close collaboration with NOAA/Geophysical Fluid Dynamics Laboratory scientists and will contribute to the NOAA research and coupled atmosphere-ocean model development involving the role of upper ocean mixing on climate and weather prediction.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.