The influence of mesoscale eddies on the detection of quasi-zonal jets in the ocean

Westward propagating Gaussian eddies with statistical characteristics estimated from altimeter observations but with purely random starting locations and times produce striated features in time‐averaged maps of zonal velocity. The striations in these simulations have magnitudes and meridional scales comparable to those reported from time‐averaged altimeter observations and model output in the central North Pacific and the California Current System. Time averages over the data records presently available are therefore not suitable for unambiguous detection of quasi‐zonal jets. The presence of mapping error and background isotropic eddy kinetic energy also bias the regionally‐averaged anisotropy of time averaged velocity fields, thus compromising the interpretation of anisotropy statistics.