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

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和预测海洋对全球变化的反应至关重要。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。该项目旨在将整个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：气体与大风中破碎的波浪产生的海雾液滴的交换。这项工作建立在以前NSF资助的项目的基础上，这些项目开发了一个用于非反应性气体的海上喷雾气体交换模型。该项目将产生一个新的海洋喷雾介导的气体转移模型，这将大大有助于了解大风中的海气交换，并需要改进气候模型和预测。该项目的结果将作为开放源代码提供。该项目将支持研究生和本科生的研究，包括指导代表性不足的第一代学生，并涉及公共宣传。 该项目的目标建立在为非反应性气体开发的基础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。通过限制喷雾液滴演变的CO2系统，研究人员还将限制碱度和pH值分布，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，相对于以前模拟的非反应性气体，海雾将在二氧化碳气体交换中发挥更重要的作用。二氧化碳，不像以前模拟的气体，将在海水喷雾蒸发过程中产生的碳酸盐和碳酸氢盐的平衡转移蒸发和酸化喷雾液滴。这一过程对于更好地理解高风速下的气体交换，改进现有的参数化方法具有重要意义。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性质，因此在海洋表面和大气化学之间建立了重要的联系。该小组将使用该模型来估计海雾在南大洋二氧化碳海气交换中的作用。这将在一个方便和相关的全球范围内提出的结果，这可能证明是有用的全球建模和气候评估。最后，该模型产生新的气体交换参数化表示的净传输系数，可以分为气泡，界面，和海喷雾传输系数。这些参数化将在不同的复杂程度上提出，如果没有波浪模型，则明确说明波浪变量。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

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.