Titre

Coherent heat patterns revealed by unsupervised classification of Argo temperature profiles in the North Atlantic Ocean

Auteur(s)

MAZE Guillaume5,1, MERCIER Herlé5,1, FABLET Ronan2,4, TANDEO Pierre2,4, LOPEZ RADCENCO Manuel2,4, LENCA Philippe3,4, FEUCHER Charlène5,1, LE GOFF Clement5,1

Type de document

Article de revue avec comité de lecture

Source

Progress in oceanography, february 2017, vol. 151, pp. 275-292

Année

2017

Résumé

A quantitative understanding of the integrated ocean heat content depends on our ability to determine how heat is distributed in the ocean and identify the associated coherent patterns. This study demonstrates how this can be achieved using unsupervised classification of Argo temperature profiles. The classification method used is a Gaussian Mixture Model (GMM) that decomposes the Probability Density Function of a dataset into a weighted sum of Gaussian modes. It is determined that the North Atlantic Argo dataset of temperature profiles contains 8 groups of vertically coherent heat patterns, or classes. Each of the temperature profile classes reveals unique and physically coherent heat distributions along the vertical axis. A key result of this study is that, when mapped in space, each of the 8 classes is found to define an oceanic region, even if no spatial information was used in the model determination. The classification result is independent of the location and time of the ARGO profiles. Two classes show cold anomalies throughout the water column with amplitude decreasing with depth. They are found to be localized in the subpolar gyre and along the poleward flank of the Gulf Stream and North Atlantic Current (NAC). One class has nearly zero anomalies and a large spread throughout the water column. It is found mostly along the NAC. One class has warm anomalies near the surface (50 m) and cold ones below 200 m. It is found in the tropical/equatorial region. The remaining four classes have warm anomalies throughout the water column, one without depth dependance (in the southeastern part of the subtropical gyre), the other three with clear maximums at different depths (100 m, 400 m and 1000 m). These are found along the southern flank of the North Equatorial Current, the western part of the subtropical gyre and over the West European Basin. These results are robust to both the seasonal variability and to method parameters such as the size of the analyzed domain.

Labos

1 : LPO - Laboratoire de Physique des Océans (UMR CNRS 6523 - IFREMER - Université de Bretagne Occidentale)
2 : SC(TB) - Dépt. Signal et Communications (Institut Mines-Télécom-Télécom Bretagne-UEB)
3 : LUSSI(TB) - Dépt. Logique des Usages, Sciences Sociales et de l'Information (Institut Mines-Télécom-Télécom Bretagne-UBL)
4 : Lab-STICC(TB) - Laboratoire en sciences et technologies de l'information, de la communication et de la connaissance (UMR CNRS 6285 - Télécom Bretagne - Université de Bretagne Occidentale - Université de Bretagne Sud - ENSTA Bretagne - Ecole Nationale d'ingénieurs de Brest)
5 : IFREMER - Institut français de recherche pour l'exploitation de la mer (IFREMER)

Mots clés

Heat patterns, Argo, Temperature profiles, North Atlantic Ocean, Unsupervised classification

Référence

17814

retour à la liste des publications
  • Institut Carnot Télécom & Société numérique
  • Télécom Bretagne Alumni
  • Université Bretagne Loire
  • Fondation Télécom
  • Institut Mines-Télécom
Technopôle Brest-Iroise - CS 83818 - 29238 Brest Cedex 3 - France - Tél : 33 (0)2 29 00 11 11 - Fax : 33 (0)2 29 00 10 00