Turbulent Exchange: Aerosols, Bubbles And Gases

湍流交换：气溶胶、气泡和气体

• 批准号: NE/J020893/1
• 负责人: Ian Brooks
• 金额: $ 50.19万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ020893%2F1
• 关键词: Turbulent; Exchange; Aerosols; Bubbles; Gases

There is now a consensus that global climate is changing in response to increasing atmospheric concentrations of greenhouse gases. These gases have natural as well as man-made sources and sinks. For carbon dioxide the largest sink is the ocean, which absorbs between 30% and 50% of the CO2 generated by the burning of fossil fuel. The direction of the exchange of gases between atmosphere and ocean depends on the difference in gas concentration between the air and water, and on a number of physical processes that modify the rate of the exchange. The most important of these processes is turbulent mixing in both the air and water close to the surface. This increases with wind speed, but the relationship is complicated by other factors such as the waves state and the thermodynamic stability of the near-surface layers of both ocean and atmosphere. At high wind speeds wave breaking generates bubbles, mixing air down into the water column. The presence of bubbles increases the rate of gas exchange, but the detailed nature of the process is not fully understood and there is considerable disagreement about the exact form of the equations that describe the rate of gas transfer. This is largely a result of a lack of sufficiently detailed measurements.Wave breaking and bubbles are also closely linked to the formation of sea-spray aerosol particles - these are important as cloud condensation nuclei. Aerosols are generated by the bursting of bubbles at the sea surface. The rate of aerosol formation is often expressed as a function of whitecap fractions on the sea surface, but there is an uncertainty of about a factor of 10 in the production rate. This suggests that whitecap fraction alone does not control the production rate, but that factors such as the size and number of bubbles produced by breaking waves may vary with other factors such as size or steepness of the wave. This project is a UK contribution to a US research cruise that aims to examine the impact of wave breaking and bubble processes on air-sea gas exchange. We will measure whitecap fraction, wave state, wave breaking statistics, and bubble properties beneath breaking waves. Measurements will be made from an 11-m spar buoy equipped with wave wires to measure the local wave height at high spatial resolution, a bubble camera to measure large bubbles near the surface, and 2 acoustical resonators to measure smaller bubbles deeper below the surface. A separate Waverider buoy will also be deployed to make longer term and independent measurements of the wave spectra. On the ship we will make direct measurements of aerosol fluxes via the eddy covariance technique, along with those of heat, water vapour, CO2, and momentum. Our partners from NOAA and the University of Hawi'i will measure fluxes of several different gases: CO2, CO, and DMS. The joint measurements of gas fluxes, and whitecap and bubble properties will allow the influence of bubbles on the flux to be evaluated directly against a variety of existing parameterizations.

现在达成的共识是，全球气候正在随着大气中温室气体浓度的增加而发生变化。这些气体有天然的以及人造的源和汇。对于二氧化碳来说，最大的汇是海洋，它吸收了化石燃料燃烧产生的 30% 到 50% 的二氧化碳。大气和海洋之间气体交换的方向取决于空气和水之间气体浓度的差异，以及改变交换速率的许多物理过程。这些过程中最重要的是靠近地表的空气和水的湍流混合。这种关系随着风速的增加而增加，但这种关系因其他因素而变得复杂，例如波浪状态以及海洋和大气近表层的热力学稳定性。在高风速下，波浪破碎会产生气泡，将空气混合到水柱中。气泡的存在增加了气体交换速率，但该过程的详细性质尚未完全了解，并且对于描述气体转移速率的方程的确切形式存在相当大的分歧。这很大程度上是由于缺乏足够详细的测量结果。波浪破碎和气泡也与海浪喷雾气溶胶颗粒的形成密切相关——这些颗粒作为云凝结核很重要。气溶胶是由海面气泡破裂产生的。气溶胶形成速率通常表示为海面白浪分数的函数，但产生速率存在约 10 倍的不确定性。这表明白浪分数本身并不能控制生产率，但破碎波浪产生的气泡的大小和数量等因素可能会随着波浪的大小或陡度等其他因素而变化。该项目是英国对美国研究巡航的贡献，旨在研究波浪破碎和气泡过程对空气-海洋气体交换的影响。我们将测量白浪分数、波浪状态、波浪破碎统计数据以及破碎波浪下的气泡特性。测量将通过一个 11 米长的圆石浮标进行，该浮标配备波浪线以高空间分辨率测量局部波高，气泡相机用于测量表面附近的大气泡，以及 2 个声谐振器用于测量表面以下更深处的较小气泡。还将部署一个单独的 Waverider 浮标，以对波谱进行长期和独立的测量。在船上，我们将通过涡流协方差技术直接测量气溶胶通量，以及热量、水蒸气、二氧化碳和动量。我们来自 NOAA 和夏威夷大学的合作伙伴将测量几种不同气体的通量：CO2、CO 和 DMS。气体通量、白帽和气泡特性的联合测量将允许根据各种现有参数直接评估气泡对通量的影响。

项目成果

Wave-Related Reynolds Number Parameterizations of CO 2 and DMS Transfer Velocities

CO 2 和 DMS 传输速度的波相关雷诺数参数化

• DOI: http://dx.10.1002/2017gl074979
• 发表时间: 2017
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Brumer S

Ocean bubbles under high wind conditions. Part 1: Bubble distribution and development

大风条件下的海洋气泡。

• DOI: http://dx.10.5194/os-2021-103
• 发表时间: 2021
• 作者: Czerski H

Toward omnidirectional and automated imaging system for measuring oceanic whitecap coverage.

用于测量海洋白浪覆盖范围的全向自动化成像系统。

• DOI: http://dx.10.1364/josaa.35.000515
• 发表时间: 2018
• 期刊: Journal of the Optical Society of America. A, Optics, image science, and vision
• 作者: Al

Whitecap Coverage Dependence on Wind and Wave Statistics as Observed during SO GasEx and HiWinGS

在 SO GasEx 和 HiWinGS 期间观察到的 Whitecap 覆盖范围对风浪统计数据的依赖性

• DOI: http://dx.10.1175/jpo-d-17-0005.1
• 发表时间: 2017
• 期刊: Journal of Physical Oceanography
• 影响因子: 3.5
• 作者: Brumer S

Wind Speed and Sea State Dependencies of Air-Sea Gas Transfer: Results From the High Wind Speed Gas Exchange Study (HiWinGS)

气海气体传输的风速和海况依赖性：高风速气体交换研究 (HiWinGS) 的结果

• DOI: http://dx.10.7916/et61-m284
• 发表时间: 2017
• 作者: Blomquist; Byron W.
• 通讯作者: Byron W.