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Evolution of intermediate water masses based on Argo float displacements

Evolution of intermediate water masses based on Argo float displacements
Evolution of intermediate water masses based on Argo float displacements
The evolution and dispersion of intermediate water masses in the ocean interior is studied. To this purpose, an empirical statistical model of Lagrangian tracers at a constant depth level is developed. The model follows the transfer operator based on 10-day deep displacements of Argo floats at ~1000 m depth. An asymptotic analysis of the model shows the existence of 10 principal stationary points (the 10 locations attract asymptotically 97% of the tracers). It takes ~1000 years to reach this asymptotic regime relevant for estimating the stationary points. For Lagrangian floats, the concept of attractor needs to be generalized in a statistical sense (versus deterministic), except for a few places in the ocean. In this new framework, a tracer has a likelihood to reach the stationary points, rather than a certainty to reach a single stationary point. The empirical statistical model is used to describe the fate of three intermediate water masses: North Pacific Intermediate Water (NPIW), Mediterranean Water (MW), and Antarctic Intermediate Water (AAIW). These experiments show a dramatic difference in the long-time behavior of NPIW, MW, and AAIW. In the permanent regime, the NPIW concentrates locally (in the Kuroshio recirculation) and the MW remains mainly regional (concentrated in the subtropical gyre of the North Atlantic), whereas the AAIW spreads globally (well mixed throughout the entire ocean).
0022-3670
1569-1586
Sévellec, F.
01569d6c-65b0-4270-af2a-35b0a77c9140
Colin De Verdiére, A.
4f5730b5-141b-40f2-8971-adb648fa5755
Ollitrault, M.
3c705901-c846-4a31-8804-66cbc837ed42
Sévellec, F.
01569d6c-65b0-4270-af2a-35b0a77c9140
Colin De Verdiére, A.
4f5730b5-141b-40f2-8971-adb648fa5755
Ollitrault, M.
3c705901-c846-4a31-8804-66cbc837ed42

Sévellec, F., Colin De Verdiére, A. and Ollitrault, M. (2017) Evolution of intermediate water masses based on Argo float displacements. Journal of Physical Oceanography, 47 (7), 1569-1586. (doi:10.1175/JPO-D-16-0182.1).

Record type: Article

Abstract

The evolution and dispersion of intermediate water masses in the ocean interior is studied. To this purpose, an empirical statistical model of Lagrangian tracers at a constant depth level is developed. The model follows the transfer operator based on 10-day deep displacements of Argo floats at ~1000 m depth. An asymptotic analysis of the model shows the existence of 10 principal stationary points (the 10 locations attract asymptotically 97% of the tracers). It takes ~1000 years to reach this asymptotic regime relevant for estimating the stationary points. For Lagrangian floats, the concept of attractor needs to be generalized in a statistical sense (versus deterministic), except for a few places in the ocean. In this new framework, a tracer has a likelihood to reach the stationary points, rather than a certainty to reach a single stationary point. The empirical statistical model is used to describe the fate of three intermediate water masses: North Pacific Intermediate Water (NPIW), Mediterranean Water (MW), and Antarctic Intermediate Water (AAIW). These experiments show a dramatic difference in the long-time behavior of NPIW, MW, and AAIW. In the permanent regime, the NPIW concentrates locally (in the Kuroshio recirculation) and the MW remains mainly regional (concentrated in the subtropical gyre of the North Atlantic), whereas the AAIW spreads globally (well mixed throughout the entire ocean).

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Accepted/In Press date: 6 March 2017
Published date: 1 July 2017

Identifiers

Local EPrints ID: 412897
URI: http://eprints.soton.ac.uk/id/eprint/412897
ISSN: 0022-3670
PURE UUID: c24a12e1-368f-47de-8aac-d7c332db478c

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Date deposited: 07 Aug 2017 16:31
Last modified: 08 Jan 2022 10:15

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Contributors

Author: F. Sévellec
Author: A. Colin De Verdiére
Author: M. Ollitrault

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