Prevalence of Deformation‐Scale Surface Currents

Abstract

AbstractUnderstanding the transport of large ocean currents, like the Gulf Stream, has been of interest since the early days of oceanography. There has been less attention on the widths of the currents, although there exist several theoretical predictions. We present a census of time‐averaged jet profiles, using in situ and satellite data. The jets are typically asymmetrical, being narrower on the side with weaker stratification. The half‐widths Lj are correlated with the local deformation radius Ld associated with the first surface mode on either side. The dependence of Lj on Ld is predicted by simple shallow water geostrophic adjustment models, with or without outcropping layers. This implies that potential vorticity is well‐mixed adjacent to the jets, due most likely to mesoscale eddies. The findings suggest that surface jet widths are determined locally, by eddy‐mean flow interactions.