Low-pressure storms drive nitrous oxide emissions in the Southern Ocean

Nitrous oxide is a potent greenhouse gas and the primary ozone-depleting agent of the 21^st century, but marine emissions of nitrous oxide remain difficult to constrain due to their spatiotemporal variability. In the Southern Ocean, where extratropical cyclones create conditions conducive to air-sea gas flux, shipboard measurements are unlikely to capture the full extent of nitrous oxide emissions due to the impracticality of sampling said storms. Here, we use machine learning to derive nitrous oxide observations from biogeochemical Argo floats, revealing that low-pressure storms amplify air-sea gradients and create hotspots of emissions. Taking these low-pressure storms into account, rather than assuming 1 atmosphere (the standard condition outside of storms), increases the net annual Southern Ocean nitrous oxide flux by 88%. Our results imply that the Southern Ocean plays a significant role in the global nitrous oxide cycle, and may be a weaker overall sink of greenhouse gases than previously thought.