Kinematic Properties in the Alboran Sea: Results from Surface and Subsurface Drifter Observations

Daniel R Tarry1, Sebastian Essink2, Ananda Pascual1, Simon Ruiz3, Poulain Pierre-Marie4, Tamay Özgökmen5, Amala Mahadevan6, Eric A D'Asaro7 and Luca Raffaele Centurioni8, (1)IMEDEA(CSIC-UIB), Esporles, Spain, (2)Massachusetts Institute of Technology, Cambridge, MA, United States, (3)IMEDEA (CSIC-UIB), Spain, (4)Centre for Maritime Research and Experimentation, La Spezia, Italy, (5)University of Miami, Rosenstiel School of Marine and Atmospheric Sciences, Miami, FL, United States, (6)Woods Hole Oceanographic Institution, Woods Hole, MA, United States, (7)Applied Physics Lab, Univ of Washington, Seattle, United States, (8)Scripps Institution of Oceanography, University of California San Diego, La Jolla, United States
Tracing the three-dimensional pathways of water parcels and particles in the upper ocean is of importance from many perspectives. Observation, understanding and prediction of the three-dimensional pathways by which water from the surface ocean makes its way into the deeper ocean is the goal of this research.

During May of 2018 a pilot cruise in the framework of the CALYPSO ONR Departmental Research Initiative took place on the Alboran Sea in the Western Mediterranean Sea. This region is characterized by a strong semi-permanent front between the fresher Atlantic water that enters the Western Mediterranean at Gibraltar, and the more saline Mediterranean waters. It is populated by organized, time evolving features (jets, fronts, and gyres) that provide an ideal test bed for a dynamical systems-based Lagrangian analysis. During this cruise nearly a hundred drifters were deployed (between SVP, CODE and CARTHE drifters).

In this work we use a least square method to calculate the differential kinematic properties of flow, divergence, vorticity and lateral strain from a set of drifters. These values are obtained through the study of the evolution in time of a patch formed by a cluster of drifters. Results from drifters at different depths, surface and 15m, show different dynamics in these layers.