The concentration of oxygen exerts major controls on life in the ocean, and its distribution in the ocean and atmosphere carries information about biological productivity, transports of mass and heat, ocean deoxygenation and global carbon sinks. Our understanding of processes underlying oxygen distributions, their key features and variability is often lacking. Here we investigate the magnitude, variability and uncertainty of the air–sea flux of oxygen, carbon dioxide and atmospheric potential oxygen over an annual cycle in the Labrador Sea. We demonstrate that two-thirds of the annual oxygen uptake occurs over only 40 days in winter and is associated with a bubble-mediated component of air–sea gas transfer linked to episodic high winds, strong cooling and deep convective mixing. By neglecting the bubble-mediated flux component, global models may underestimate oxygen and atmospheric potential oxygen uptake in regions of convective deep-water formation by up to an order of magnitude. Uncertainties in wind speed products lead to additional major (up to 80%) uncertainty in air–sea fluxes in these critical regions. Our findings may help explain observation–model discrepancies in distributions of atmospheric potential oxygen and imply that oxygen levels in the deep ocean are more sensitive to climate change than currently thought.

氧气的浓度对海洋中的生物起主要控制作用，其在海洋和大气中的分布可提供有关生物生产力，质量和热量的运输，海洋脱氧和全球碳汇的信息。我们通常对氧气分布，其关键特征和可变性的过程缺乏了解。在这里，我们研究了拉布拉多海一年周期内海，海氧气，二氧化碳和大气中的氧气通量的大小，变异性和不确定性。我们证明，每年三分之二的年度氧气吸收仅发生在冬季的40天之内，并且与气泡-介导的海气传输成分有关，与阵风，强冷和深对流混合有关。通过忽略气泡介导的通量成分，整体模型可能低估了对流深水形成区域中的氧气和大气中潜在的氧气摄入量，最多可能低一个数量级。风速产品的不确定性会导致这些关键区域的海-海通量产生更大的不确定性（高达80％）。我们的发现可能有助于解释观测模型与大气中潜在氧气分布的差异，并暗示深海中的氧气水平对气候变化的敏感性要高于当前的想象。