Lulabel Ruiz Seitz, Mara Freilich

Submesoscale dynamics, operating at spatial scales of O(1−10 km) and temporal scales of O(1 day), are particularly important for marine ecosystems as they occur on similar timescales as phytoplankton growth, enabling biophysical feedbacks. While submesoscale dynamics are known to impact biological fluxes by modifying nutrient upwelling, horizontal transport has traditionally been assumed to only redistribute phytoplankton without altering concentrations. However, variations in submesoscale dispersion may significantly impact total biogeochemical flux if biological reactions occur during dispersal. By parameterizing the effects of dispersion due to lateral stirring on flux, within an eastern boundary current region, we show that enhanced dispersion yields a near-linear increase in offshore flux, with the magnitude modulated by phytoplankton growth rates
and ambient nutrient availability. These findings identify a pathway for improving parameterizations of biogeochemical fluxes, while revealing a source of uncertainty in their prediction by climate models.