Dynamics of the Persian Gulf Outflow

Friday, 19 December 2014
Clément Vic1, Guillaume Roullet1, Xavier Capet2 and Xavier J Carton1, (1)Laboratoire de Physique des Océans, Brest, France, (2)Université Pierre et Marie Curie, LOCEAN , IPSL, Paris, France
Situated north of the Arabian Sea, the Persian Gulf is subject to strong evaporation which
dominates precipitation. Warm and salty waters are thus produced in this marginal sea and
feed an outflow at depth in the Arabian Sea. Although its signature in terms of water mass
properties is observed far offshore the Strait of Hormuz, mechanisms that govern its dynamics
remain poorly studied. High resolution (2 km) regional and idealized numerical models are
used to investigate the dynamics and spreading pathways of the Persian Gulf outflow. The
Persian Gulf Water (PGW) undergoes a stage of hydrostatic adjustment that sets its depth
around 200 m. Its fate is then found to be strongly driven by highly energetic seasonal surface-
intensifed mesoscale eddies that stir the characteristic properties of the PGW. Interactions
with boundaries, noticeably capes, also lead to detachment of short-lived intense submesoscale
coherent vortices that are advected along the edges of the mesoscale eddies. Strain and shear
generated by these eddies are in fact comparable to the relative vorticity, thus compete with it.