H040-0020
Frontal convergence and vertical velocities measured by drifters in the Alboran Sea
Tuesday, 8 December 2020
Poster
Daniel R Tarry1, Sebastian Essink2, Ananda Pascual1, Simon Ruiz1, Poulain Pierre-Marie3, Tamay M Ozgokmen4, Luca Raffaele Centurioni5, J. Thomas Farrar6, Andrey Shcherbina7, Amala Mahadevan8 and Eric A D'Asaro9, (1)IMEDEA(CSIC-UIB), Esporles, Spain, (2)Applied Physics Laboratory University of Washington, Seattle, WA, United States, (3)Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Trieste, Italy, (4)University of Miami, Miami, FL, United States, (5)Scripps Institution of Oceanography, La Jolla, CA, United States, (6)Woods Hole Oceanographic Inst, Department of Physical Oceanography, Woods Hole, MA, United States, (7)Applied Physics Laboratory University of Washington, Kenmore, WA, United States, (8)Woods Hole Oceanographic Institution, Woods Hole, MA, United States, (9)Applied Physics Lab, Univ of Washington, Seattle, WA, United States
Abstract:
Horizontal and vertical motions associated with mesoscale (10-100 km) and submesoscale (1-10 km) features, such as fronts, meanders, eddies and filaments, play a critical role in the distribution of physical properties and biogeochemical tracers in the ocean. This study makes use of a multiplatform dataset obtained in a frontal region in the Alboran Sea in the framework of the ONR Departmental Research Initiative, ”CALYPSO” (Coherent Lagrangian Pathways from the Surface Ocean to Interior). Submesoscale filaments can generate regions of convergence where strong vertical exchanges occur.
In this work we show the capability of different platforms to observe a surface density submesoscale front. The large amount of drifters deployed in a small area together with 3D Lagrangian float and repeated UCTD sections allows us to observe in high resolution the small scale variations in the submesoscale. Spatial distributions of horizontal divergence and vertical vorticity are calculated from clusters of drifters deployed at two different depths. The results obtained indicate a high space-time variability. Convergence values around -f indicate the presence of vertical velocities in the region. Negative vertical velocities estimated from the drifter-calculated divergence reach values down to -100 m/day. These results double the estimates of vertical velocities from previous studies in the region. These values are compared with the measurements made by a 3D Lagrangian float which subducted in the middle of the drifter swarm. In addition, vertical sections of UCTD are used to understand the hydrographical state of the upper ocean. The study is completed with an error analysis of the kinematic properties which shows an error variance around the 10%.
