Measuring the space and time evolution of the geometric, kinematic and dynamic properties of oceanic breaking waves

测量海洋碎浪的几何、运动学和动力学特性的空间和时间演变

• 批准号: 2284568
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2284568
• 关键词: Measuring; space; time; evolution; geometric

The overarching goal of this project is to provide a better understanding and description of oceanic breaking waves for oceanographic, atmospheric science and engineering purposes.Breaking waves at the ocean surface represent the most extreme flow occurring at the ocean-atmosphere interface: they generate high levels of upper ocean turbulence, entrain air into the water column which drives bubble-mediated air-sea exchange of gas and aerosol particles, disperse pollutants and nutrients, alter maximum wave height and crest height statistics and can generate large slamming forces on structures in the marine environment. Consequently breaking waves modulate the energy of the upper-ocean and surface wave field, drive ocean-atmosphere interfacial exchanges that influence weather and climate dynamics and impact engineering design.Due to their intermittent occurrence at the ocean surface, associated high fluid velocities and high air fractions, detailed in-situ measurements of breaking waves in the ocean are extremely rare. Consequently, relatively little is known about the likelihood, scale and severity of individual oceanic breaking waves. Moreover, the complex hydrodynamics associated with breaking waves make accurate numerical simulations highly challenging and computationally expensive. To address these challenges, this project seeks to develop a digital image-based remote sensing approach to describe the characteristics of oceanic breaking waves by measuring the space-time evolving whitecap foam signal generated by individual breaking waves. The student will have access to a multi-year dataset of stereovision sea surface images gathered from the Acqua Alta oceanographic research Tower (AAT) in the Adriatic Sea by co-supervisor Benetazzo. These images provide a detailed measurement of the time-evolving 3-D sea surface elevation field across a large area of ocean surface, from which directional wave spectra can be calculated. Further image datasets will be obtained by the student through the installation of additional camera equipment on the AAT during the course of the project. Through the development of bespoke digital image processing algorithms, the student will analyse the geometric, kinematic and dynamic properties of individual breaking waves and develop new statistical descriptions of their associated energy dissipation. These results will be complemented with data from a state-of-the-art numerical spectral wave model provided by co-supervisor Bidlot at the European Centre of Medium Range Forecasting (ECMWF). The student has the opportunity of working closely with the ECMWF during the project. The ECMWF modelling component represents the pathway by which the results from the field study can be applied in a global context, therefore representing a key component of the work.The student will have the opportunity to apply the results generated from the field analysis of breaking waves to estimate breaking-wave-driven bubble-mediated air-sea fluxes of carbon dioxide concentration and aerosol production fluxes on a global scale using the ECMWF wave model. The breaking wave data collected will enable the student to develop breaking wave descriptions that can inform offshore engineering design standards. As such, this project offers the student a unique opportunity to work with supervisors with a range of expertise and make important breakthrough contributions to the description of breaking waves relevant to several diverse disciplines.

The overarching goal of this project is to provide a better understanding and description of oceanic breaking waves for oceanographic, atmospheric science and engineering purposes.Breaking waves at the ocean surface represent the most extreme flow occurring at the ocean-atmosphere interface: they generate high levels of upper ocean turbulence, entrain air into the water column which drives bubble-mediated air-sea exchange of gas and aerosol particles, disperse pollutants and nutrients, alter maximum wave height and波峰高度统计数据，可以在海洋环境中的结构上产生大型猛击力。因此，打破波会调节上海角和表面波场的能量，驱动海洋 - 大气界面交流，影响天气和气候动态以及影响工程设计。因此，关于单个海洋破裂波的可能性，规模和严重性，相对较少。此外，与断裂波相关的复杂流体动力学使准确的数值模拟高度挑战性和计算昂贵。为了应对这些挑战，该项目旨在开发一种基于数字图像的遥感方法，以通过测量由单个断裂波产生的时空发展的WhiteCap泡沫信号来描述海洋破裂波的特征。该学生将可以通过共同居民Benetazzo的Accuaa Alta海洋学研究塔（AAT）收集的立体电视台海面图像的多年数据集。这些图像可详细测量横跨海面的大面积的时间不断变化的3-D海面高程场，可以从中计算出方向波光谱。在项目过程中，学生将通过在AAT上安装其他相机设备来获得更多图像数据集。通过开发定制的数字图像处理算法，学生将分析单个断裂波的几何，运动学和动态特性，并开发出有关其相关能量耗散的新统计描述。这些结果将与来自欧洲中等范围预测中心（ECMWF）的共同竞标者提供的最先进的数值光谱波模型的数据相辅相成。在项目期间，学生有机会与ECMWF紧密合作。 ECMWF建模组件代表了可以在全球环境中应用现场研究结果的途径，因此代表工作的关键组成部分。学生将有机会应用破坏波的现场分析所产生的结果，以估算波动驱动的燃料式气泡介导的空气介导的空气 - 使用二氧化碳浓缩量的空气量型生产范围逐渐成生产效果，这是一个逐渐划分的范围。收集的破坏波数据将使学生能够开发出可以为离岸工程设计标准提供信息的破坏波描述。因此，该项目为学生提供了与具有一系列专业知识的主管合作的独特机会，并为描述与几个不同学科相关的破坏浪潮做出了重要的突破性贡献。