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You are here: Home / Events / Seminars / seminaires-septembre-2018-aout-2019 / jeudi-14-mars-warm-core-rings-in-the-gulf-of-mexico-from-basin-scale-to-fine-scale

by SEMSOU last modified Feb 28, 2019 03:00 PM
When Mar 14, 2019
from 02:00 PM to 03:00 PM
Where salle Coriolis
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Thomas Meunier

Chercheur au CICESE, Ensenada (Mexique)


Title : Warm-core rings in the Gulf of Mexico: from basin scale to fine scale.

 

Abstract : Loop current eddies (LCE) are large warm-core rings sporadically detaching from the Loop current (LC), and drifting through the Gulf of Mexico (GoM). They largely dominate the GoM's circulation and control the redistribution of heat and salt towards the basin's interior, dramatically affecting hurricanes and storm cells formation. They also have a significant impact on the oil industry, eventually forcing deep water drilling operations to stop for weeks. For the past 2 decades, LCEs have mostly been studied through altimetry and regional numerical modelling, and little is known about their vertical thermohaline structure. In the frame of the CIGOM project, a series of glider missions repeatedly sampled a LCE, from its detachment until its agony along the GoM's western platform, revealing its thermohaline properties. Thanks to their fine spatial resolution, the glider surveys revealed an unsuspected richness of processes, from submesoscale to fine scale, occurring within the LCE. The presence of at least three intrathermocline eddies, embedded in the main thermocline of the LCE was obvious in the Brunt-Väisälä sections. They were associated with strong negative potential vorticity anomalies. They are believed to form through mixing and Rossby adjustment, possibly through internal wave breaking, or frictional processes in the Yucatan channel prior to LCE detachment. Evidences of layering below, and near the edges of the recently detached LCE, also brought a new candidate for the diffusion of thermohaline properties towards the surrounding GoM's water. High resolution QG modeling of an idealized warm-core ring showed that the vertical variance cascade leading to the observed layering was likely triggered by the stirring of tracer anomalies by the eddy's vertically sheared azimuthal flow, similar to layering around interior vortices. The LCE was also associated with unexpectedly large temperature and salinity anomalies, carrying integrated heat and salt excesses of nearly 1 billion TJ and 22 billion tons, respectively. Their impact on the basin scale seasonal and long term heat and salt budgets will also be discussed.

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