Internal Wave‐Driven Mixing in the North Atlantic From Finescale Observations and the IDEMIX Closure

Abstract Oceanic turbulent mixing plays a fundamental role in global circulation and climate regulation, yet its spatial variability remains poorly observed, especially in the deep ocean. This study presents a detailed observational analysis of finescale turbulence in two North Atlantic regions, using repeated full‐depth profiles of stratification and horizontal velocity. We characterize spatial patterns in the dissipation of turbulent kinetic energy by examining their relationship with topographic features, and the sources of internal gravity wave energy. Elevated dissipation values are found over rough topography such as the Mid‐Atlantic Ridge and at the western boundaries, consistent with regions of enhanced internal wave generation. Observed shear‐to‐strain ratios further illuminate the contributions of different wave sources and highlight contrasts between the northern and tropical Atlantic. To complement these observations, we compare dissipation rates with predictions from the model IDEMIX (Internal Wave Dissipation, Energy and Mixing), with a particular focus on the impact of lee wave forcing (LWF). Results demonstrate that incorporating LWF significantly improves agreement with observations in the northern Atlantic, particularly in deeper layers. IDEMIX effectively reproduces large‐scale mixing patterns, though its performance is more sensitive to parameter choices in regions of enhanced near‐bottom velocity gradients and rough topography. Though IDEMIX is a model framework, it offers a physically grounded reference to interpret mixing patterns where direct measurements are limited.