Latent and Sensible Heat Flux at the Spray-Laden Air-Sea Interface

大风情况下的海气界面，如飓风，是一个跨越大气科学和海洋学界限的重要课题。众所周知，海雾水滴会影响海洋上方表层的温度和水分分布，进而影响相关的大气过程。这一奖项将为研究人员和他的学生提供一个机会，利用直接数值模拟对这些过程进行数值建模，使研究人员能够跟踪单个液滴在风中移动的情况。该项目的潜在影响是改进对热带气旋的预测，但开发的数值技术可能会对各种科学学科产生影响。这项工作还将通过对研究生和本科生的培训，为未来的科学工作者做出贡献。研究人员计划通过一系列数值实验来研究海雾对海-气界面上的热量、水汽和动量交换的作用。由于在这些条件下很难进行测量，海雾在大风条件下对这些交易所的作用尚不确定。研究人员开发了一种数值技术，通过剪切驱动的湍流跟踪单个拉格朗日液滴，并对每个颗粒实施双向动量耦合，允许直接计算体积矩通量修正。该项目将通过在液滴和周围流动之间实施双向热力学耦合来扩展这项工作，从而能够直接评估喷雾对潜热和显热通量以及由此产生的温度和湿度分布的影响。需要回答的具体研究问题包括：1)在充满热力学耦合液滴颗粒的环境中，感热和潜热(和热焓)的垂直通量是否超过无负载情况下的垂直通量？2)液滴蒸发在多大程度上增强了盐分进入海洋的通量，这会增强海洋边界层的混合吗？3)海-气界面上方的平均热量和湿度分布是否会发生变化？4)需要何种浓度的水滴才能观察到对热量和水汽通量的影响？5)当处于热力平衡状态时，预计会有什么样的水滴尺寸分布在海-气界面上方？

The air-sea interface in high-wind situations, like hurricanes, is an important topic that crosses boundaries between atmospheric sciences and oceanography. Sea spray droplets are known to affect the temperature and moisture distribution in the surface layer above the ocean, which in turn can affect associated atmospheric processes. This award will provide an opportunity for a researcher and his students to work on numerical modeling of these processes using direct numerical simulation, which allows researchers to follow individual droplets as they move along in the wind. The potential impact of this project is on improved prediction of tropical cyclones, but the numerical techniques developed could potentially have an impact across a variety of scientific disciplines. The work would also contribute to the future scientific workforce through the training of a graduate student and undergraduate student.The researcher plans to address the role of sea spray on the exchanges of heat, moisture, and momentum at the air-sea interface through a suite of numerical experiments. The role of sea spray on these exchanges at high winds is uncertain due to the difficulty in making measurements in these conditions. The researcher has developed a numerical technique to track individual Lagrangian droplets through a shear-driven turbulent flow, and two-way momentum coupling was enforced for each particle allowing for a direct calculation of the bulk moment flux modifications. This project would extend that work by implementing two-way thermodynamic coupling between the droplets and the surrounding flow, allowing for a direct evaluation of spray's influence on latent and sensible heat flux and the resulting profiles of temperature and moisture. The specific research questions to be answered include: 1) Do the vertical fluxes of sensible and latent heat (and enthalpy) in an environment laden with thermodynamically-coupled droplet particles exceed those of an unladen case? 2) To what degree is the flux of salinity into the ocean enhanced by droplet evaporation, and can this lead to enhanced mixing in the ocean boundary layer? 3) Do the mean profiles of heat and humidity change immediately above the air-sea interface? 4) What concentrations of water droplets are necessary to see any effects on heat and moisture fluxes? 5) What size distribution of spray droplets can be expected when in thermodynamic equilibrium immediately above the air-sea interface?