Quantifying the Contribution of Ocean Mesoscale Eddies to Low Oxygen Extreme Events
Jamie Atkins, Oliver Andrews, Ivy Frenger
Abstract
Abstract Ocean mesoscale eddies have been identified as drivers of localized extremely low dissolved oxygen concentration ([O 2 ]) conditions in the subsurface. We employ a global physical‐biogeochemical ocean model at eddy‐permitting resolution to conduct a census of open‐ocean eddies near Eastern Boundary Upwelling Systems adjacent to tropical Oxygen Minimum Zones (OMZs). We track cyclonic and anticyclonic eddies with a surface signature over the period 1992–2018 and isolate their subsurface oxygen characteristics. We identify strongly deoxygenating eddies and quantify their contribution to low [O 2 ] extreme events. Our results show that model simulated low [O 2 ] extreme event frequency is 2–7 times higher in eddies versus non‐eddying locations, with regionally more than half of low [O 2 ] extreme events outside of the permanent OMZs being associated with eddies. Our study highlights the need for further work to investigate the drivers, characteristics and potential ecosystem impacts of low [O 2 ] extreme events.