Measurements of the Coupled Development of the Surface Wave Field and Marine Atmospheric Boundary Layer with Fetch

风致波场与海洋大气边界层的耦合发展是海气相互作用中的一个基本问题。虽然已经根据无量纲提取得到了简单的无量纲波高和峰值频率的幂律表达式，但波浪方向谱的演变预测仍然依赖于有关风输入、非线性波-波相互作用和破碎耗散的假设。在海洋大气边界层的模拟中也存在类似的不确定性。边界层的演变与波场是耦合的，动量、热通量和水分通量取决于海况，特别是波浪破碎。虽然在中尺度和盆地尺度的海气相互作用模式中，这些过程的细节可能被平均化，或降级为亚栅格尺度的状态，但需要改进的小尺度海气通量模式来改进中等风浪条件下的预测。此外，一阶不确定性在大风中仍然存在。众所周知，从风到流的动量流（或大气边界层上的阻力）的大部分首先通过波场。将动量通量转化为洋流的主要机制是破波。破裂是湍流（增强热量和质量传递）、气泡和海洋气溶胶的重要来源。海洋喷雾和气溶胶对生物地球化学、云物理和地球辐射平衡具有特别重要的意义。本文介绍了一种在中至大风条件下海气通量、大气边界层和表面波场随风速变化的机载测量方案。空中实验将在冬季期间从NCAR C-130在墨西哥太平洋沿岸的特万特佩克湾进行，当时北风在太平洋上空以高达40节或更高的速度吹了几天。利用现代远程成像、测距、测绘和定位技术，我们将对离岸风吹时的波浪场进行详细测量。利用现代机载大气湍流和通量测量技术，我们将测量大气边界层的演变，并研究与波场的耦合。利用空展式一次性落差探空仪和axbt对海洋大气边界层和海洋混合层的发展进行了剖面分析。测量结果将与海气通量和风浪演变的耦合模式进行比较。我们将开发大气边界层依赖于获取的模式和更详细的地表波过程依赖于获取的模式；尤其是打破。该项目将通过多种机制对科学和社会产生更广泛的影响。这项研究是由小规模海气相互作用的基本问题驱动的，但结果将在经济上重要的海洋-大气耦合模型中得到应用，以改进天气和气候预测。这项研究的结果将直接纳入SIO/UCSD和UCI的课程，该项目开发的设备和技术将用于两所机构的研究生教育和各个领域的研究。该项目将为SIO/UCSD和UCI的不同/代表性不足的群体的夏季本科生研究人员提供研究机会，并将在学年期间提供本科生助理的机会。该项目将用于两所机构对K-12学生进行科学教育，并提供科学方面的就业机会。将在SIO设立一个项目网站，广泛传播研究结果。

ABSTRACTPI/Institution: Melville / SIO Proposal No: OCE-0242083The coupled development of the wind-generated wave field and the marine atmospheric boundary layer as a function of fetch remains a fundamental problem in air-sea interaction. While simple power-law expressions for the dimensionless wave height and peak frequency have been obtained in terms of the dimensionless fetch, predictions of the evolution of the wave directional spectrum still depend on assumptions about the wind input, nonlinear wave-wave interactions and dissipation by breaking. Similar uncertainties exist in the modeling of the marine atmospheric boundary layer. The evolution of the boundary layer and the wave field are coupled, with the momentum, heat and moisture fluxes depending on the sea state, and especially on wave breaking. While the details of these processes may be averaged out, or relegated to subgrid-scale status in meso- and basin-scale models of air-sea interaction, improved models of small-scale air-sea fluxes are required to improve predictions under moderate wind and wave conditions. Moreover, first-order uncertainties remain at high winds. It is well known that much of the momentum flux from winds to currents (or the drag on the atmospheric boundary layer) first passes through the wave field. The primary mechanism for transferring that momentum flux to currents is wave breaking. Breaking is an important source of turbulence (that enhances heat and mass transfer), and of entrained bubbles and marine aerosols. Marine spray and aerosols are of particular importance for biogeochemisty, for cloud physics, and for the Earth's radiation balance. This proposal describes a program of airborne measurements of the evolution of the air-sea fluxes, the atmospheric boundary layer and the surface wave field as a function of fetch in moderate to high winds. Airborne experiments will be conducted from the NCAR C-130 in the Gulf of Tehuantepec, of the Pacific coast of Mexico during winter when northerly mountain-gap winds blow at up to 40 knots or more for several days out over the Pacific. Using modern remote imaging, ranging, mapping and positioning techniques, we will make detailed measurements of the wave field with fetch as winds blow offshore. Using modern airborne atmospheric turbulence and flux measurement techniques, we will measure the evolution of the atmospheric boundary layer and investigate the coupling with the wave field. Using air-deployable expendable dropsondes and AXBTs we will profile the development of the marine atmospheric boundary layer and the ocean mixed layer with fetch. Measurements will be compared with coupled models of air-sea fluxes and wind-wave evolution. We will develop fetch-dependent models of the atmospheric boundary layer and more detailed fetch-dependent models of surface-wave processes; especially breaking. This project will have a broader impact on science and society through a variety of mechanisms. The research is motivated by basic questions in small-scale air-sea interaction, but the results will find application in economically-important coupled ocean-atmosphere models for improved weather and climate prediction. The results of this research will be directly incorporated into classes at SIO/UCSD and UCI, and the equipment and techniques developed in this project will be used in graduate education and research across a variety of fields at both institutions. The project will provide research opportunities for summer undergraduate research fellows from diverse /underrepresented groups at both SIO/UCSD and UCI, and opportunities for undergraduate assistants will be provided during the school year. The project will be used to educate K-12 students in science, and career opportunities in science, at both institutions. A project web site will be established at SIO to broadly disseminate the results of the research.