Heterogeneity of phytoplankton response to submesoscale processes in the global ocean

Oceanic submesoscale processes are believed to play a pivotal role in influencing phytoplankton growth and distribution, essentially influencing oceanic primary productivity and carbon cycling. However, our understanding of how phytoplankton respond to these dynamics remains fragmentary. Here, by combining surface drifter data and satellite observations, we show a rich geographic variability in the response of phytoplankton to submesoscale ageostrophic events over the global ocean. Substantial phytoplankton biomass and chlorophyll enrichments are observed during submesoscale processes in mid-high latitude regions and coastal upwelling systems. However, negligible phytoplankton biomass increases with notable chlorophyll increases are observed in the tropical ocean and subtropical gyres, suggesting that phytoplankton are likely undergoing physiological adjustments. Globally, about half of the chlorophyll growth driven by strong submesoscale ageostrophic events is due to physiological adjustments rather than biomass enrichment, calling for a reevaluation of the effects of submesoscale processes on oceanic productivity and carbon cycling.