A Numerical Study of the Magellan Plume

ELBIO D. PALMA; RICARDO P. MATANO

JOURNAL OF GEOPHYSICAL RESEARCH

AMER GEOPHYSICAL UNION

Año: 2012 vol. 117 p. 1 - 16

0148-0227

In this modeling study we investigate the dynamical mechanisms controlling thespreading of the Magellan Plume, which is a low-salinity tongue that extends alongthe Patagonian Shelf. Our results indicate that the overall characteristics of the plume(width, depth, spreading rate, etc.) are primarily influenced by tidal forcing, whichmanifests through tidal mixing and tidal residual currents. Tidal forcing produces a homogenization of the plume's waters and an offshore displacement of its salinity front.The interaction between tidal and wind-forcing reinforces the downstream and upstreambuoyancy transports of the plume. The influence of the Malvinas Current on the MagellanPlume is more dominant north of 50S, where it increases the along-shelf velocities andgenerates intrusions of saltier waters from the outer shelf, thus causing a reduction of thedownstream buoyancy transport. Our experiments also indicate that the northern limit ofthe Magellan Plume is set by a high salinity discharge from the San Matias Gulf.Sensitivity experiments show that increments of the wind stress cause a decrease of thedownstream buoyancy transport and an increase of the upstream buoyancy transport.Variations of the magnitude of the discharge produce substantial modifications in thedownstream penetration of the plume and buoyancy transport. The Magellan dischargegenerates a northeastward current in the middle shelf, a recirculation gyre south of theinlet and a region of weak currents father north.