Submesoscale Tidal-Inlet Dipoles Resolved Using Stereo WorldView Imagery

A pair of high-resolution visible-band satellite images, acquired 65 s apart and analyzed using an optical-flow algorithm, is shown to provide a realistic snapshot of the velocity field of dipolar vortices (dipoles) emitted from the Gulf of San Jose, Argentina. The results reveal the expected counter-rotating vortices within three dipoles, as well as one monopole; the magnitude of vorticity ranges from 8 to 29 times the local Coriolis parameter. Analysis of the derived velocity and vorticity fields yields an estimate of 0.27 ms
^-1
for the dipole self-propagation velocity, which is the part of the physics that allows transport of gulf-derived material into open waters. Dipole size, measured as the distance between vortex centers, increases with distance from the source area in a manner consistent with the effects of entrainment of ambient sea water. Given favorable imaging conditions, the general approach used here can provide a detailed portrayal of local circulation patterns-one suitable for use in validating high-resolution numerical models, especially in coastal areas having complex bathymetry.