Mechanisms for the emergence of ocean striations in the North Pacific

Recent observations suggest that the mean mesoscale oceanic zonal velocity field is dominated by alternating jet‐like features often referred to as striations. Here the generating dynamics of Northeast Pacific striations are explored with a set of 120 year eddy‐permitting model simulations. Simulations are conducted with decreasing complexity toward idealized configurations retaining the essential dynamics and forcing necessary for striation development. For each simulation, we diagnose the spin‐up of the ocean model and the sensitivity of striation generation to topography, coastal geometry, and wind stress, which modulates the gyre circulation and the nonlinearity of the flow field. Results indicate that Northeast Pacific striations develop predominantly at the eastern boundary and migrate westward in congruence with beta‐plumes in both the nonlinear and quasi‐linear regimes. Mean striations are governed by coastline geometry, which provides quasi‐steady vorticity sources energized by eastern boundary current instabilities. Key Points Northeast Pacific striations form as coastal vorticity propagates offshore via beta‐plumes Vorticity is anchored by coastal geometry, so striations remain stationary Striation magnitude is constrained at the shelf by potential vorticity trapping