3D Lagrangian pathways in the Alboran Sea

Helga Huntley1, A. D. Kirwan Jr1, Baptiste Mourre2 and Pierre F J Lermusiaux3, (1)University of Delaware, Newark, DE, United States, (2)Balearic Islands Coastal Observing and Forecasting System (SOCIB), Palma, Spain, (3)Massachusetts Institute of Technology, Cambridge, MA, United States
The dynamics in the Alboran Sea in the western Mediterranean Sea is dominated by one or two mesoscale gyres that regularly develop between the African and Spanish coasts. They are characterized by sharp fronts separating the relatively fresh Atlantic inflow from the saltier Mediterranean waters. Subduction along these fronts is thought to play a major role in the vertical transport in this part of the ocean, connecting the surface to the deeper waters. To identify such 3D pathways in high-resolution model runs from the CALYPSO (Coherent Lagrangian Pathways from the Surface Ocean to Interior) project, we compute finite time Lyapunov exponents (FTLE), which have long been successfully used to map out 2D pathways. Rather than stitching together layer-by-layer maps, however, a fully 3D methodology is applied that was developed and tested in semi-analytic dynamic models. We report on the FTLE structures surrounding the major vortices in the Alboran Sea and the implication for vertical transport in the area.