Collaborative Research: Measuring Air-Sea Gas Exchange in High Winds for Improvement of Physics-Based Air-Sea Transfer Parameterizations

合作研究：测量强风中的海气交换，以改进基于物理的海气传输参数化

• 批准号: 1036062
• 负责人: Barry Huebert
• 金额: $ 83.7万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1036062&HistoricalAwards=false
• 关键词: Collaborative; Research; Measuring; Air; Sea

Predicting future climate requires, among other factors, accurate estimates of the atmospheric concentration of carbon dioxide and other greenhouse gases and an understanding of the feedbacks between atmospheric radiative processes and surface ocean biogeochemistry. In this context, of particular interest to climate modeling is an understanding of the exchange of gases (like carbon dioxide and dimethylsufide, DMS) between the atmosphere and ocean surface. DMS is a contributor to secondary aerosol and cloud condensation nuclei production. Numerous physical processes are responsible for gas exchange, including momentum transfer to the ocean surface from wind shear, transfer of momentum directly to waves via pressure differential across the wave face (form drag), breaking waves which generate bubbles of air forced into the water column, near-surface biogeochemical processes which modify surface tension and water column thermal stability, gas species chemical properties, etc. In order to parameterize air-sea gas exchange for application in climate models, it is crucial to understand which of these processes are important under specific environmental conditions. Recent experimental work has shown that simple parameterizations based solely on wind speed are not adequate to describe the gas transfer, and this is particularly true at the higher wind regimes where breaking wave processes dominate the gas exchange. For example, observations have shown that gas transfer from bubbles is enhanced for less soluble gases, and theory suggests that form drag becomes increasingly important at high winds; this effect will modulate the water-side mixing from tangential shear transfer. This realization has led to the development of a new air-sea gas transfer parameterization which expresses the exchange in terms of the forcing physical processes. However, the parameterization has not been tested at higher wind regimes where the bulk of the globally-integrated transfer occurs. A four-year effort will be undertaken which includes two cruises on ships-of-opportunity and one dedicated cruise with the intention of investigating air-sea gas transfer across a range of wind speeds (the dedicated cruise will focus on high winds), a range of gas solubility (e.g., DMS, carbon dioxide, acetone, carbon monoxide, sulfur dioxide), and a range of wave states (control on fetch and distribution of wind stress between tangential and form drag components) and wave breaking (bubble processes).The results from the experimental work will be used to further develop the new gas transfer parameterization which is applicable in larger scale climate models that include the effects of air-sea gas transfer. This potentially leads to better predictions of future climate, and these projections will be of significant value to society and policy decision makers. The project will include scientist participation in workshops focused on providing local earth science teachers with tools necessary to understand and communicate climate science to their elementary and high school students. Scientist lectures will be teleconferenced to remote sites, and the project contribution to the workshops will include imparting knowledge about connections between observations and models, as well as assisting teachers in understanding the limitations and strengths of models in predicting climate.

除其他因素外，还需要对二氧化碳和其他温室气体的大气浓度进行准确估计，以及对大气辐射过程与表面海洋生物地球化学之间的反馈理解的准确估计。在这种情况下，气候建模特别感兴趣的是对大气和海洋表面之间气体的交换（例如二氧化碳和二甲基二甲基，DMS）的理解。 DMS是二次气溶胶和云凝结核产生的贡献者。许多物理过程负责气体交换，包括从风剪到海面的动量转移到海洋表面，动量通过压力差异直接转移到波浪面上的波动（形成拖动），破坏波浪，这些波浪产生的空气被强迫进入水柱中的空气，近乎表面的生物地球化学过程，以使表面张力和水柱稳定性构成序列，以使其具有化学性质，以使其具有化学性质，等等。要了解这些过程在特定的环境条件下很重要。最近的实验工作表明，仅基于风速的简单参数化不足以描述气体的传递，而在较高的风状态下，破坏波过程主导了气体交换。例如，观察结果表明，对于较低的可溶性气体，气体转移的气体转移增强了，理论表明，在大风中，形态阻力变得越来越重要。这种效果将通过切向剪切转移调节水侧混合。这种认识导致了新的空气气体传输参数化的发展，该参数在强迫过程中表达了交换。但是，在大部分全球整合转移发生的较高风向状态下，尚未对参数化进行测试。 A four-year effort will be undertaken which includes two cruises on ships-of-opportunity and one dedicated cruise with the intention of investigating air-sea gas transfer across a range of wind speeds (the dedicated cruise will focus on high winds), a range of gas solubility (e.g., DMS, carbon dioxide, acetone, carbon monoxide, sulfur dioxide), and a range of wave states (control on fetch and distribution of wind切线和形式阻力组件之间的应力）和波浪破裂（气泡过程）。实验工作的结果将用于进一步开发新的气体传递参数化，该参数适用于大规模气候模型，其中包括空气气体转移的影响。这可能会更好地预测未来气候，这些预测对社会和政策决策者具有重要价值。该项目将包括科学家参加的研讨会，致力于为当地的地球科学教师提供必要的工具，以了解和传达气候科学与小学生和高中生。科学家的讲座将与远程站点进行电信，并且对研讨会的项目贡献将包括传授有关观察和模型之间联系的知识，并协助教师了解模型在预测气候方面的限制和优势。