The effects of ocean tides in North Atlantic subpolar area studied by high-resolution ocean model

Ocean tides play an important role in shaping circulation, stratification, and mixing in the North Atlantic subpolar region, yet their impacts at fine spatial scales remain insufficiently quantified. In this study, we investigate the effects of ocean tides in the North Atlantic subpolar area using a km-scale high-resolution ocean model. Two numerical experiments are conducted: a control simulation including full tidal forcing and a sensitivity experiment in which tidal forcing is suppressed. By comparing these experiments, we isolate the tidal contributions to sea surface elevation, currents, and vertical mixing.

The results show that tides substantially enhance barotropic and baroclinic variability, particularly over complex topography such as continental slopes and ridges. Tidal currents intensify near-bottom shear and promote vertical mixing, leading to modifications in stratification and water mass properties. In addition, tide–topography interactions generate internal tides that propagate into the interior basin, influencing submesoscale circulation and energy redistribution. These tidal effects further modulate the mean flow and variability in the subpolar gyre, with implications for regional heat and salt transport. Meanwhile, natural variability also plays a role when distinguishing between tidal effects and internally generated variability.

Our findings highlight the importance of explicitly resolving tidal processes in high-resolution ocean models for accurately representing circulation and mixing in the North Atlantic subpolar region. This study emphasizes that tides are a key component of subpolar ocean dynamics and should be considered in studies of climate-relevant processes in this region.