TY - JOUR
T1 - Water mass transports and pathways in the North Brazil ‐ Equatorial Undercurrent retroflection
AU - Vallès‐Casanova, Ignasi
AU - Fraile‐Nuez, Eugenio
AU - Martín‐Rey, Marta
AU - Sebille, Erik
AU - Cabré, Anna
AU - Olivé‐Abelló, Anna
AU - Pelegrí, Josep L.
N1 - Funding Information:
This work has been funded by the Spanish Government through project SAGA (Ministerio de Ciencia, Innovacion y Universidades, ref. no. RTI2018-100844-B-C33). I.V.C. was funded by the Spanish Government through a FPI contract (Ministerio de Economía y Competitividad, ref. no. BES-2015-071314) and M.M.R. was funded by the European Union (MSCA-IF-EF-ST FESTIVAL, grant agreement no. 797236) and the Spanish government through a Juan de la Cierva Incorporation grant. The authors wish to acknowledge the Mercator Ocean for providing the GLORYS2v4 reanalysis data and the GTMBA Project Office of NOAA/PMEL for providing the PIRATA data. The authors are also thankful to our two anonymous reviewers for their constructive and useful comments and suggestions. This article is a publication of the Unidad Oceano y Clima of the Universidad de Las Palmas de Gran Canaria, an R + D + I-CSICassociate unit. The authors also recognize the institutional support of the Spanish Government through the Severo Ochoa Center of Excellence accreditation (CEX2019-000928-S).
Funding Information:
This work has been funded by the Spanish Government through project SAGA (Ministerio de Ciencia, Innovacion y Universidades, ref. no. RTI2018‐100844‐B‐C33). I.V.C. was funded by the Spanish Government through a FPI contract (Ministerio de Economía y Competitividad, ref. no. BES‐2015‐071314) and M.M.R. was funded by the European Union (MSCA‐IF‐EF‐ST FESTIVAL, grant agreement no. 797236) and the Spanish government through a Juan de la Cierva Incorporation grant. The authors wish to acknowledge the Mercator Ocean for providing the GLORYS2v4 reanalysis data and the GTMBA Project Office of NOAA/PMEL for providing the PIRATA data. The authors are also thankful to our two anonymous reviewers for their constructive and useful comments and suggestions. This article is a publication of the Unidad Oceano y Clima of the Universidad de Las Palmas de Gran Canaria, an R + D + I‐CSICassociate unit. The authors also recognize the institutional support of the Spanish Government through the Severo Ochoa Center of Excellence accreditation (CEX2019‐000928‐S).
Publisher Copyright:
© 2022 The Authors.
PY - 2022/5
Y1 - 2022/5
N2 - The equatorial retroflection of the North Brazil Current (NBC) into the Equatorial Undercurrent (EUC) and its posterior tropical recirculation is a major regulator for the returning limb of the Atlantic Meridional Overturning Circulation. Indeed, most surface and thermocline NBC waters retroflect at the equator all the way into the central and eastern Atlantic Ocean, before they recirculate back through the tropics to the western boundary. Here, we use cruise data in the western equatorial Atlantic during April 2010 and reanalysis time series for the equatorial and tropical waters in both hemispheres in order to explore the recirculation pathways and transport variability. During the 1998–2016 period, the annual-mean EUC transports 15.1 ± 1.3 Sv at 32°W, with 2.8 ± 0.4 Sv from the North Atlantic and 11.4 ± 1.3 Sv from the South Atlantic. At 32°W most of the total EUC transport comes from the western boundary retroflection south of 3°N (7.2 ± 0.9 Sv), a substantial fraction retroflects north of 3°N (5.6 ± 0.4 Sv), and the remaining flow (2.3 Sv) joins through the interior basin. The South Atlantic subtropical waters feed the EUC at all thermocline depths while the North Atlantic and South Atlantic tropical waters do so at the surface and upper-thermocline levels. The EUC transport at 32°W has a pronounced seasonality, with spring and fall maxima and a range of 8.8 Sv. The 18 yr of reanalysis data shows a weak yet significant correlation with an Atlantic Niño index, and also suggests an enhanced contribution from the South Atlantic tropical waters during 2008–2016 as compared with 1997–2007.
AB - The equatorial retroflection of the North Brazil Current (NBC) into the Equatorial Undercurrent (EUC) and its posterior tropical recirculation is a major regulator for the returning limb of the Atlantic Meridional Overturning Circulation. Indeed, most surface and thermocline NBC waters retroflect at the equator all the way into the central and eastern Atlantic Ocean, before they recirculate back through the tropics to the western boundary. Here, we use cruise data in the western equatorial Atlantic during April 2010 and reanalysis time series for the equatorial and tropical waters in both hemispheres in order to explore the recirculation pathways and transport variability. During the 1998–2016 period, the annual-mean EUC transports 15.1 ± 1.3 Sv at 32°W, with 2.8 ± 0.4 Sv from the North Atlantic and 11.4 ± 1.3 Sv from the South Atlantic. At 32°W most of the total EUC transport comes from the western boundary retroflection south of 3°N (7.2 ± 0.9 Sv), a substantial fraction retroflects north of 3°N (5.6 ± 0.4 Sv), and the remaining flow (2.3 Sv) joins through the interior basin. The South Atlantic subtropical waters feed the EUC at all thermocline depths while the North Atlantic and South Atlantic tropical waters do so at the surface and upper-thermocline levels. The EUC transport at 32°W has a pronounced seasonality, with spring and fall maxima and a range of 8.8 Sv. The 18 yr of reanalysis data shows a weak yet significant correlation with an Atlantic Niño index, and also suggests an enhanced contribution from the South Atlantic tropical waters during 2008–2016 as compared with 1997–2007.
KW - Lagrangian transports
KW - Tropical Atlantic
KW - western boundary current
UR - http://www.scopus.com/inward/record.url?scp=85130610106&partnerID=8YFLogxK
U2 - 10.1029/2021JC018150
DO - 10.1029/2021JC018150
M3 - Article
SN - 2169-9275
VL - 127
SP - 1
EP - 21
JO - Journal of Geophysical Research: Oceans
JF - Journal of Geophysical Research: Oceans
IS - 5
M1 - e2021JC018150
ER -