The Dynamical Structure of a Warm Core Ring as Inferred from Glider Observations and Along-Track Altimetry

Type Article
Date 2021-07
Language English
Author(s) Meunier Thomas1, Pallas Sanz Enric2, de Marez Charly3, Perez Juan2, Tenreiro Miguel2, Ruiz Angulo Angel4, Bower Amy1
Affiliation(s) 1 : Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA.
2 : Ctr Invest Cient & Educ Super Ensenada, Ensenada 22860, Baja California, Mexico.
3 : Lab Oceanog Phys & Spatiale, F-29280 Plouzane, Brittany, France.
4 : Univ Iceland, Inst Earth Sci, IS-102 Reykjavik, Iceland.
Source Remote Sensing (2072-4292) (Mdpi), 2021-07 , Vol. 13 , N. 13 , P. 2456 (23p.)
DOI 10.3390/rs13132456
WOS© Times Cited 3
Note This article belongs to the Special Issue Recent Advances in Ocean Physics, Geochemistry and Biology from Unmanned Marine Vehicles
Keyword(s) gliders, altimetry, mesoscale, eddies, warm-core rings, potential vorticity, gulf of Mexico

This study investigates the vertical structure of the dynamical properties of a warm-core ring in the Gulf of Mexico (Loop Current ring) using glider observations. We introduce a new method to correct the glider's along-track coordinate, which is, in general, biased by the unsteady relative movements of the glider and the eddy, yielding large errors on horizontal derivatives. Here, we take advantage of the synopticity of satellite along-track altimetry to apply corrections on the glider's position by matching in situ steric height with satellite-measured sea surface height. This relocation method allows recovering the eddy's azimuthal symmetry, precisely estimating the rotation axis position, and computing reliable horizontal derivatives. It is shown to be particularly appropriate to compute the eddy's cyclo-geostrophic velocity, relative vorticity, and shear strain, which are otherwise out of reach when using the glider's raw traveled distance as a horizontal coordinate. The Ertel potential vorticity (PV) structure of the warm core ring is studied in details, and we show that the PV anomaly is entirely controlled by vortex stretching. Sign reversal of the PV gradient across the water column suggests that the ring might be baroclinically unstable. The PV gradient is also largely controlled by gradients of the vortex stretching term. We also show that the ring's total energy partition is strongly skewed, with available potential energy being 3 times larger than kinetic energy. The possible impact of this energy partition on the Loop Current rings longevity is also discussed.

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Meunier Thomas, Pallas Sanz Enric, de Marez Charly, Perez Juan, Tenreiro Miguel, Ruiz Angulo Angel, Bower Amy (2021). The Dynamical Structure of a Warm Core Ring as Inferred from Glider Observations and Along-Track Altimetry. Remote Sensing, 13(13), 2456 (23p.). Publisher's official version : , Open Access version :