Spray-mediated air-sea gas exchange of carbon dioxide in high winds

强风中喷雾介导的二氧化碳气海气体交换

• 批准号: 2218781
• 负责人: Penny Vlahos
• 金额: $ 38.54万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2218781&HistoricalAwards=false
• 关键词: Spray; mediated; air; sea; gas

Understanding the processes that control the exchange of gases between the ocean and atmosphere is crucial to understanding the role of the ocean in the global carbon cycle and predicting the response of the ocean to global change. Gas exchange is more complicated for carbon dioxide than for many other gases because carbon dioxide reacts with water to form carbonic acid, bicarbonate ions, and carbonate ions. This project seeks to incorporate the full carbonate system into modeling a particular process affecting ocean-atmosphere gas exchange: the exchange of gases with droplets of sea spray produced by breaking waves in high winds. This work builds on previous NSF-funded projects that developed a model for sea spray gas exchange for non-reactive gases. The project will generate a new model of sea spray-mediated gas transfer that will contribute greatly to understanding of air-sea gas exchange in high winds and is needed to improve climate models and predictions. The results from the project will be made available as open source code. The project will support graduate and undergraduate student research, incorporate mentoring of underrepresented and first-generation students, and involve public outreach. The objectives of this project build upon the foundational Andreas Gas Exchange Spray model (AGES) developed for non-reactive gases, by adding the components of a reacting gas system and coupling these to a scalable physical model. By constraining the CO2 system as a spray droplet evolves, the investigators will also constrain the alkalinity and pH profile and therefore the chemical environment that controls other reactions and transformations within the droplet. The investigators expect that, relative to previously modelled non-reactive gases, sea spray will play a much more significant role for CO2 gas exchange. CO2, unlike the previously modeled gases, will be produced during sea spray evaporation as the carbonate and bicarbonate equilibria shift in an evaporating and acidifying spray droplet. This process is significant for a better understanding of gas exchange at high wind speeds to improve current parameterizations. This project also constrains the chemistry of sea spray drops before reaching the aerosol stage and therefore creates a significant link between surface-ocean and atmospheric chemistry. The team will use the model to generate an estimate of the role sea spray serves in CO2 air-sea exchange in the Southern Ocean. This will present the results in a convenient and relevant global context which may prove useful for global modeling and climate assessments. Finally, the model generates novel gas-exchange parameterizations expressed in terms of a net transfer coefficient that can be divided into bubble, interfacial, and sea spray transfer coefficients. These parameterizations will be proposed at different levels of complexity with and without explicitly accounting for the wave variables in case a wave model is not available.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

了解控制海洋和大气之间气体交换的过程对于了解海洋在全球碳循环中的作用以及预测海洋对全球变化的响应至关重要。二氧化碳的气体交换比许多其他气体更复杂，因为二氧化碳与水反应形成碳酸、碳酸氢根离子和碳酸根离子。该项目旨在将完整的碳酸盐系统纳入影响海洋-大气气体交换的特定过程的建模中：气体与大风中破浪产生的海浪液滴的交换。这项工作建立在之前 NSF 资助的项目的基础上，该项目开发了一种用于非反应性气体的海浪气体交换模型。该项目将产生一种新的海浪介导的气体转移模型，该模型将极大地有助于理解强风中的海气交换，并且是改进气候模型和预测所必需的。该项目的结果将作为开源代码提供。该项目将支持研究生和本科生的研究，纳入对代表性不足的学生和第一代学生的指导，并涉及公众宣传。 该项目的目标建立在针对非反应气体开发的基础 Andreas 气体交换喷雾模型 (AGES) 的基础上，通过添加反应气体系统的组件并将其耦合到可扩展的物理模型。通过在喷雾液滴演化时限制 CO2 系统，研究人员还将限制碱度和 pH 分布，从而限制控制液滴内其他反应和转化的化学环境。研究人员预计，相对于之前模拟的非反应气体，海浪喷雾将在二氧化碳气体交换中发挥更重要的作用。与之前模拟的气体不同，二氧化碳将在海水喷雾蒸发过程中产生，因为蒸发和酸化喷雾液滴中的碳酸盐和碳酸氢盐平衡会发生变化。这一过程对于更好地了解高风速下的气体交换以改善当前的参数化具有重要意义。该项目还限制了海洋喷雾滴在达到气溶胶阶段之前的化学成分，因此在海洋表面和大气化学之间建立了重要的联系。该团队将使用该模型来估计海浪在南大洋二氧化碳海气交换中的作用。这将在方便且相关的全球背景下呈现结果，这可能对全球建模和气候评估有用。最后，该模型生成以净传递系数表示的新颖的气体交换参数化，该净传递系数可分为气泡、界面和海浪传递系数。这些参数化将以不同的复杂程度提出，无论是否明确考虑波浪变量，以防波浪模型不可用。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的评估进行评估，被认为值得支持。影响审查标准。