This study investigates the complex interactions between near-inertial oscillations (NIOs) and a mesoscale eddy in the Lofoten Basin in the Norwegian Sea, focusing on the submesoscale dynamics. Using surface drifters deployed during the Northern Ocean Rapid Surface Evolution (NORSE) project, we observed variations in near-inertial kinetic energy (KE) within the center of the Lofoten Basin Eddy (LBE), a semipermanent anticyclonic vortex. NIOs, which are the ocean's response to wind forcing, can propagate vertically as near-inertial internal waves, contributing significantly to ocean mixing. Our results demonstrate that NIOs within the LBE experience amplification due to interactions with submesoscale features, particularly sea surface height gradients. These interactions result in a non-zero net exchange between potential and kinetic energy, leading to increased near-inertial kinetic energy at the center of the eddy. The drifter data reveal three distinct near-inertial energy events, with different spatial patterns depending on the drifters’ proximity to the eddy center. A modified slab model incorporating sea surface height terms accurately captured the observed wind work and energy input into the system, highlighting the importance of eddy dynamics in modulating near-inertial kinetic energy. This study suggests that submesoscale sea surface height gradients may play a significant role in the amplification of NIOs and energy transfer in mesoscale eddies. The findings have implications for understanding ocean mixing and energy budgets, especially with the advent of high-resolution altimetry data from satellite missions like SWOT, which can better capture these small-scale interactions.

Data collected by surface drifters manufactured for the Global Drifter Program at the Lagrangian Drifter Lab at Scripps Institution of Oceanography (https://gdp.ucsd.edu/ldl/). The drifters were deployed in the North Sea around 70°N and 4°E in September 2021 as part of the Office of Naval Research funded program "Northern Ocean Rapid Surface Evolution" (NORSE) pilot cruise aboard the R/V Neil Armstrong. The drifters sampled 15-30 min intervals and the dataset has been subsampled to 1h.