Abstract The immense river discharge in the northern Bay of Bengal (nBoB) represents a major source of buoyancy, generating significant density fronts and stratification that are fundamental to submesoscale dynamics (SMDs). Through a set of high‐resolution numerical experiments, this study investigates the effect of river discharge on SMDs in the nBoB. The simulation incorporating river discharge shows a significantly higher accuracy in reproducing the observed thermohaline structures. The most active SMDs are observed in winter due to the seasonal maximum of the mixed layer depth (MLD). River discharge intensifies the SMDs in the western part of the nBoB, while suppressing it in the east, especially in winter. In the submesoscale kinetic energy budget, the generation of SMDs by baroclinic instability is largely counteracted by pressure work, with a minor contribution from energy conversion via barotropic instability. Further analysis reveals that river discharge affects SMDs by altering the horizontal buoyancy gradient and MLD, which collectively regulate the vertical buoyancy flux. Vertical heat flux within the mixed layer is suppressed by river discharge, while vertical salt flux is enhanced (suppressed) in (below) the surface layer. These findings underscore the necessity of applying accurate river discharge in ocean models to better represent coastal multiscale dynamics.
Duan et al. (Wed,) studied this question.