Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction

Significance Transport of organic carbon from the sunlit surface ocean to deeper depths drives net oceanic uptake of CO 2 from the atmosphere. However, mechanisms that control this carbon export remain poorly constrained, limiting our ability to model and predict future changes in this globally important process. We show that the flux of sinking particles (typically considered the dominant form of downward transport of organic carbon) is twice as high at a frontal system, relative to surrounding waters or to nonfrontal conditions. Furthermore, downward transport by subduction leads to additional carbon export at the front that is similar in magnitude to the sinking flux. Such enhanced C export at episodic and mesoscale features needs to be incorporated into biogeochemical forecast models.