Collaborative Research: Influence of wind and bottom generated turbulence on air-sea gas exchange in shallow water environments

能量和气体的海气转移对于预测短期天气和长期气候趋势至关重要。在过去的几十年里，人们付出了相当大的努力，用风速等广泛测量的变量来参数化这些通量。然而，这些参数化在浅海地区是不充分的，在浅海地区，取水、波浪和底部产生的湍流影响负责海气通量的物理机制，这对我们理解重要的环境过程（如珊瑚礁代谢或碳循环）的能力有影响。此外，浅海水域生态系统容易受到人为污染，导致缺氧或缺氧。为了了解这些持续受到人为扰动的生态系统的未来状态，必须建立生物地球化学预算和通量，包括在空气-水界面上的交换，即需要对控制气体交换的因素有定量的了解。本项目将测量浅层珊瑚礁的海气通量和影响其变异性的多种物理变量。预计这项研究的结果将使人们更好地了解风、流、波等物理过程对产生表面和底部驱动的湍流的影响，以及它们如何控制浅海水域的海气交换。它们还应该允许这些过程根据容易测量的环境变量（如风速、流速和水深）进行参数化。在更局部的层面上，pi将通过参与本科生研究机会、针对K-12学生的当地科学活动和研究生指导，继续努力传播物理和化学海洋学领域的科学知识。该项目将为两名研究生和一名本科生提供多学科培训。为了确定控制浅海环境中气体交换的因素，将在夏威夷凯恩奥赫湾的堡礁上连续两年进行一系列实验。在实验过程中，将使用示踪剂（N2O、SF6、罗丹明WT）和CO2的涡流相关方差来测量气体传递速度，同时测量风、流、波和湍流等过程。有了在凯恩湾收集的数据，ppi将：(i)评估何时或是否将公海风速/气体交换参数化应用于浅水环境是有效的（ii）提高我们对风、流、波等物理过程如何与浅水底部相互作用以产生表面-；（iii）研究浅海水域表面和底部产生的湍流如何控制海气交换（iv）根据容易测量的环境变量，如风速、流速和水深，参数化浅水环境中的气体交换。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Air-sea transfers of energy and gases are critically important for predictions of short term weather, as well as long term climate trends. Over the past decades, considerable effort has been devoted to parameterizing these fluxes in terms of widely measured variables such as wind speed. However, these parameterizations are inadequate in shallow coastal regions where fetch, waves, and bottom-generated turbulence influence the physical mechanisms responsible for the air-sea fluxes, which have implications for our ability to understand important environmental processes such as coral reef metabolism or carbon cycling. Furthermore, shallow coastal water ecosystems are susceptible to anthropogenic pollution, leading to hypoxia or anoxia. In order to understand the future states of these ecosystems that are exposed to continued anthropogenic perturbations, biogeochemical budgets and fluxes have to be established, including exchanges across the air-water interface, i.e., they require quantitative knowledge of factors controlling gas exchange. This project will measure the air-sea gas fluxes and multiple physical variables contributing to their variability in a shallow coral reef. It is anticipated that the results from this study will yield improved understanding of the influence of physical processes such as wind, currents, waves on producing surface-, and bottom-driven turbulence, and how they control air-sea gas exchange in shallow coastal waters. They should also allow these processes to be parameterized in terms of easily measured environmental variables such as wind speeds, current velocities, and water depth. On a more local level, the PIs will continue their efforts toward disseminating scientific understanding in the field of physical and chemical oceanography by participating in undergraduate research opportunities, local science events targeted at K-12 students, and graduate student advising. This project will provide multidisciplinary training to two graduate students, and an undergraduate student.A series of experiments will be performed over two consecutive years on the barrier reef of Kane'ohe Bay, Hawaii to determine factors that control gas exchange in shallow ocean environments. During the experiment, gas transfer velocities will be measured with tracers (N2O, SF6, Rhodamine WT) and eddy covariance of CO2, along with concurrent measurements of processes such as wind, current, waves and turbulence. With the data collected in Kane'ohe Bay, the PIs will: (i) Assess when or whether it is valid to apply open ocean wind speed/gas exchange parameterizations toshallow water environments (ii) Improve our understanding of how physical processes such as wind, currents, waves interact with the shallow bottom to produce surface-, and bottom-driven turbulence (iii) Examine how surface and bottom generated turbulence control air-sea gas exchange in shallow coastal waters (iv) Parameterize gas exchange in shallow water environments in terms of easily measured environmental variables such as wind speeds, current velocities, and water depth.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.