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

对于短期天气和长期气候趋势的预报来说，海气之间的能量和气体转移至关重要。在过去的几十年里，已经投入了相当大的努力来根据广泛测量的变量(如风速)来参数化这些通量。然而，这些参数化在浅海地区是不够的，在那里，取水、波浪和海底产生的湍流影响了造成海-气通量的物理机制，这意味着我们有能力理解重要的环境过程，如珊瑚礁新陈代谢或碳循环。此外，沿海浅水生态系统容易受到人为污染，导致缺氧或缺氧。为了了解这些受到持续人为干扰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，包括通过空气-水界面的交换，即它们需要对控制气体交换的因素进行定量了解。该项目将测量浅层珊瑚礁中的气-海气体通量和影响其可变性的多个物理变量。预计这项研究的结果将有助于更好地理解风、流、波浪等物理过程对产生表层和底部驱动的湍流的影响，以及它们如何控制沿海浅海的气-海气体交换。它们还应该允许根据容易测量的环境变量(如风速、水流速度和水深)对这些过程进行参数化。在更本地化的层面上，海洋学专业人员将继续努力，通过参与本科生研究机会、针对K-12学生的本地科学活动和研究生咨询，传播对物理和化学海洋学领域的科学理解。该项目将为两名研究生和一名本科生提供多学科培训。将连续两年在夏威夷凯恩湾的堡礁上进行一系列实验，以确定控制浅海环境中气体交换的因素。在实验期间，将使用示踪剂(N2O、SF6、罗丹明WT)和二氧化碳的涡动协方差来测量气体传输速度，同时还将测量风、流、波浪和湍流等过程。利用在Kane‘ohe Bay收集的数据，PIS将：(I)评估何时或是否有效地将开放海洋风速/气体交换参数化应用于浅水环境(Ii)加深我们对风、流、波浪等物理过程如何与浅水底部相互作用以产生表面和海底驱动的湍流的理解(Iii)研究表层和底部产生的湍流如何控制浅海近海的气海气体交换(Iv)根据容易测量的环境变量，如风速、海流速度、这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.