Collaborative Reseach: Investigating Bubble-Mediated Gas Exchange in a Strongly Convective Ocean during the Bubble Exchange in the Labrador Sea (BELS) Experiment

拉布拉多海是北大西洋的一部分，位于加拿大和格陵兰岛之间，是世界上少数几个深海通风的地方之一。它是盐类和溶解气体进入深海的地方，从而决定了深海的化学和物理环境。早些时候的一项研究使用了从2016年秋季到2017年春季在拉布拉多海进行实地考察期间收集的数据，结果表明，用于计算海-气通量的传统数学公式，即气体进出海洋的速度，对拉布拉多海来说是不准确的。原因可能与那里独特的环境有关：大风、大浪和寒冷的空气。早些时候的研究表明，不可能准确估计向深海供应了多少气体，如氧气和二氧化碳。由于氧气对海洋动物至关重要，而二氧化碳是导致全球变暖的温室气体之一，因此迫切需要开发更准确的大气-海洋气体通量公式，以便在拉布拉多海和其他地方使用。在这个项目中，科学家们将于2023年秋季前往拉布拉多海，使用最近开发的技术，如自动驾驶车辆，对海-气界面附近的海洋和大气条件进行详细测量。此外，还将对上层海洋的物理和化学环境进行高保真计算机模拟，只有使用超级计算机才能实现。通过综合新的数据和计算机解决方案，将开发出适用于包括拉布拉多海在内的世界海洋的更准确的海-气通量数学公式。拟议研究的主要目标是更好地了解气泡过程和气泡介导的气体转移，并提出适用于世界海洋，包括高纬度海洋典型的强对流环境的订正参数。一个相关的目标是量化溶解度对气泡介导的气体传递的影响。拟议的研究包括一个观测程序和一个建模程序。观测部分是拉布拉多海气泡交换实验(BERS)的一部分，该实验是2023年秋季在拉布拉多海进行的一项国际计划。研究人员将测量气泡对二氧化碳/氧气/氮气的海气侵入速率和3He/SF6的逃逸速率，并对混合层中的气体通量强迫进行详细测量，包括气泡和湍流。他们将采用各种方法，包括一维和三维预算，船上直接涡流协方差通量，以及自动驾驶车辆。这些观测将使用最先进的数值模型来合成，这些模型同时模拟湍流洋流、气泡和溶解气体。该项目旨在改善大气-海洋气体通量的参数化，并减少未来海洋通风期间气体吸收预测的不确定性，这可能是全球变暖造成的。该奖项反映了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。

The Labrador Sea, part of the North Atlantic Ocean between Canada and Greenland, is one of the few places in the world where the deep ocean is ventilated. It is where salts and dissolved gases enter the deep ocean, thereby setting the chemical and physical environments of the deep ocean. An earlier study using data collected during a field campaign in the Labrador Sea from fall 2016 to spring 2017 showed that the traditional mathematical formulas used to calculate air-sea gas fluxes, i.e., how fast gases go in and out of the ocean, are inaccurate for the Labrador Sea. The reason may have to do with the unique environment there: strong wind, big waves, and chilling air. The earlier study indicated that it is not possible to make accurate estimates of how much gases, such as oxygen and carbon dioxide, are supplied to the deep ocean. Since oxygen is crucial to marine animals and carbon dioxide is one of the greenhouse gases contributing to global warming, there is an urgent need to develop more accurate formulas for air-sea gas fluxes that could be used in the Labrador Sea and elsewhere. In this project, scientists will go to the Labrador Sea in fall 2023 to make detailed measurements of oceanic and atmospheric conditions near the air-sea interface using recently developed techniques such as autonomous vehicles. In addition, high-fidelity computer simulations, only possible using supercomputers, will be conducted for the physical and chemical environments of the upper ocean. By synthesizing the new data and computer solutions, more accurate mathematical formulas for air-sea gas fluxes suitable for the world’s oceans including the Labrador Sea will be developed. The overarching objectives of the proposed study are to better understand bubble processes and bubble-mediated gas transfer and to propose a revised parameterization suitable for the world’s ocean, including strongly convective environments typical of the high-latitude ocean. An associated objective is to quantify the effect of solubility on bubble-mediated gas transfer. The proposed research includes an observational program and a modeling program. The observational component is part of the Bubble Exchange in the Labrador Sea (BELS) experiment – an international program during the Fall of 2023 in the Labrador Sea. The researchers will measure bubble-mediated air-sea invasion rates of CO2/O2/N2 and evasion rates of 3He/SF6 and make detailed measurements of gas flux forcing including bubbles and turbulent currents in the mixed layer. They will employ various approaches including 1D- and 3D-budgets, shipboard direct eddy covariance fluxes, as well as autonomous vehicles. These observations will be synthesized using state-of-the-art numerical models that concurrently simulate turbulent ocean currents, bubbles, and dissolved gases. The project aims to improve parameterizations of air-sea gas fluxes and reduce uncertainty in future predictions of gas uptake during ocean ventilation that may result from global warming.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.