Combining an Eddy Detection Algorithm with In-Situ Measurements to Study North Brazil Current Rings

Type Article
Date 2023-04
Language English
Author(s) Subirade Corentin1, 2, L'Hégaret Pierre1, Speich Sabrina1, Laxenaire Rémi1, 3, Karstensen Johannes4, Carton Xavier5
Affiliation(s) 1 : Laboratoire de Meteorologie Dynamique (LMD), UMR 8539 CNRS, Ecole Normale Superieure, 75005 Paris, France
2 : Laboratoire d’Océanologie et Géosciences (LOG), UMR 8187, Université Littoral Côte d’Opale, 59140 Dunkerque, France
3 : Laboratoire de L’Atmosphere et des Cyclones (LACy), UMR 8105 CNRS, Universite de La Reunion, Meteo-France, 97744 Saint-Denis, France
4 : GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany
5 : Laboratoire d’Océanographie Physique et Spatiale (LOPS), Institut Universitaire Européen de la Mer IUEM, Université de Bretagne Occidentale (UBO), Brest, CNRS, IRD, Ifremer, 29280 Plouzané, France
Source Remote Sensing (2072-4292) (MDPI), 2023-04 , Vol. 15 , N. 7 , P. 1897 (32p.)
DOI 10.3390/rs15071897
Note This article belongs to the Special Issue Recent Advances on Oceanic Mesoscale Eddies
Keyword(s) ocean mesoscale eddies, satellite altimetry, tropical Atlantic, EUREC(4)A-OA, multi-decadal time series, spatio-temporal variability

North Brazil Current (NBC) rings are believed to play a key role in the Atlantic Ocean circulation and climate. Here, we use a new collection of high-resolution in-situ observations acquired during the EUREC4A-OA field experiment together with satellite altimetry to define, with unprecedented detail, the structure and evolution of these eddies. In-situ observations reveal a more complex structure than previously documented. In particular, we highlight a measurable impact of the Amazon outflow in creating a barrier layer over a large portion of the eddies. We show that this unprecedented data set allows us to estimate the accuracy of satellite altimetry gridded fields. The geostrophic velocities derived from satellite altimetry turn out to be considerably lower (up to 50% in amplitude) than the values measured by current meters. However, eddy properties as detected by TOEddies, a newly developed algorithm show to be relatively precise. For example, the eddy center and maximum azimuthal velocity contour fall within 25 ± 5 km and 16 ± 9 km, respectively, from the in-situ observed values. We apply TOEddies to 27 years of satellite altimetry to investigate the generic NBC rings behavior. We found a mean generation rate of 4.5 ± 1.1 rings per year, and a strong seasonal cycle in all eddy properties.

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Subirade Corentin, L'Hégaret Pierre, Speich Sabrina, Laxenaire Rémi, Karstensen Johannes, Carton Xavier (2023). Combining an Eddy Detection Algorithm with In-Situ Measurements to Study North Brazil Current Rings. Remote Sensing, 15(7), 1897 (32p.). Publisher's official version : , Open Access version :