Preprints
https://doi.org/10.5194/egusphere-2022-402
https://doi.org/10.5194/egusphere-2022-402
13 Jun 2022
 | 13 Jun 2022

Revisiting the tropical Atlantic western boundary circulation from a 25-year time series of satellite altimetry data

Djoirka Minto Dimoune, Florence Birol, Fabrice Hernandez, Fabien Léger, and Moacyr Araujo

Abstract. Geostrophic currents derived from altimetry are used to investigate the surface circulation in the Western Tropical Atlantic over the 1998–2017 period. Using six horizontal sections defined to capture the current branches of the study area, we investigate their respective variations at both seasonal and interannual time-scales as well as the spatial distribution of these variations. Our results show that the central branch of the South Equatorial Current, the North Brazil Current component located south of the equator, the Guyana Current and the northern branch of the South Equatorial Current at 42° W have similar annual cycles, with maxima/minima during boreal winter-spring/October–November. In contrast, the seasonal cycles of the North Brazil Current branch located between the equator and 7–8° N, the North Brazil Current retroflected branch and the North Equatorial Countercurrent show maxima/minima during boreal fall/May. West of 42° W, an eastward current is observed between 0°–2° N, identified as the equatorial extension of the retroflected branch of the North Brazil Current. It is part of a large cyclonic circulation observed between 0°–6° N and 35°–45° W during boreal spring. The North Equatorial Countercurrent shows a two-core structure during the second half of the year, when we also observe the two regions where the North Brazil Current retroflects. The latter can be related to the wind stress curl seasonal changes. At interannual scales, depending on which side of the equator, the North Brazil Current exhibits two opposite scenarios related to the tropical Atlantic Meridional Mode phases. The interannual variability of the North Equatorial Countercurrent and of the northern branch of the South Equatorial Current (in terms of both strength and/or latitudinal shift) at 42° W are also associated to the Atlantic Meridional Mode, while they are associated to the zonal mode phases at 32° W.

Journal article(s) based on this preprint

07 Mar 2023
Revisiting the tropical Atlantic western boundary circulation from a 25-year time series of satellite altimetry data
Djoirka Minto Dimoune, Florence Birol, Fabrice Hernandez, Fabien Léger, and Moacyr Araujo
Ocean Sci., 19, 251–268, https://doi.org/10.5194/os-19-251-2023,https://doi.org/10.5194/os-19-251-2023, 2023
Short summary

Djoirka Minto Dimoune et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Djoirka Minto Dimoune on behalf of the Authors (29 Nov 2022)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (30 Nov 2022) by Anne Marie Treguier
RR by Anonymous Referee #1 (13 Dec 2022)
RR by Anonymous Referee #2 (05 Jan 2023)
ED: Reconsider after major revisions (09 Jan 2023) by Anne Marie Treguier
AR by Djoirka Minto Dimoune on behalf of the Authors (21 Jan 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (22 Jan 2023) by Anne Marie Treguier
RR by Anonymous Referee #2 (24 Jan 2023)
ED: Publish subject to technical corrections (30 Jan 2023) by Anne Marie Treguier
AR by Djoirka Minto Dimoune on behalf of the Authors (01 Feb 2023)  Author's response   Manuscript 

Journal article(s) based on this preprint

07 Mar 2023
Revisiting the tropical Atlantic western boundary circulation from a 25-year time series of satellite altimetry data
Djoirka Minto Dimoune, Florence Birol, Fabrice Hernandez, Fabien Léger, and Moacyr Araujo
Ocean Sci., 19, 251–268, https://doi.org/10.5194/os-19-251-2023,https://doi.org/10.5194/os-19-251-2023, 2023
Short summary

Djoirka Minto Dimoune et al.

Djoirka Minto Dimoune et al.

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
The study of the surface current branches derived from satellite data in the northwest tropical Atlantic show similar seasonal variability, except the North Brazil Current branch which enter into Guyana Current and which also show a similar variability to the currents in the southwest. A cyclonic circulation and a surface eastward flow are shown in the equatorial region. The year-to-year variations of the currents are related to the tropical Atlantic climate modes, depending on their location.