FN Archimer Export Format PT J TI Near-surface western boundary circulation off Northeast Brazil BT AF Dossa, Alina N. Costa da Silva, Alex Chaigneau, Alexis Eldin, Gérard Araujo, Moacyr Bertrand, Arnaud AS 1:1;2:1;3:2,3,4;4:2;5:1,5;6:1,6,7; FF 1:;2:;3:;4:;5:;6:; C1 Laboratório de Oceanografia Física Estuarina e Costeira, Depto. Oceanografia, UFPE, Recife-PE, Brazil Laboratoire d’Études en Géophysique et Océanographie Spatiale (LEGOS), Université de Toulouse, CNES, CNRD, IRD, UPS, Toulouse, France Institut de Recherches Halieutiques et Océanologiques du Bénin (IRHOB), Cotonou, Benin International Chair in Mathematical Physics and Applications (ICMPA–UNESCO Chair), University of Abomey‐Calavi, Cotonou, Benin Brazilian Research Network on Global Climate Change, São José dos Campos, SP, Brazil Institut de Recherche pour le Développement (IRD), MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France Universidade Federal Rural de Pernambuco, Recife, Brazil C2 UNIV FED PERNAMBUCO UFPE, BRAZIL UNIV TOULOUSE, FRANCE IRHOB, BENIN ICMPA–UNESCO, BENIN REDE CLIMA, BRAZIL IRD, FRANCE UNIV FED RURAL PERNAMBUCO UFRPE, BRAZIL UM MARBEC IN WOS Cotutelle UMR copubli-france copubli-univ-france copubli-int-hors-europe copubli-sud IF 4.416 TC 29 UR https://archimer.ifremer.fr/doc/00659/77143/78468.pdf LA English DT Article CR ABRACOS ABRACOS 2 BO Antea DE ;Western Tropical Atlantic;North Brazil Undercurrent;North Brazil Current;Flow-topography interaction;Mesoscale activity;ADCP AB In the tropical Atlantic Ocean, the North Brazil Undercurrent (NBUC) and the North Brazil Current (NBC) play important roles as near-surface northward paths for the Atlantic meridional overturning circulation. To investigate the meridional evolution of the near-surface western boundary circulation in that region, two surveys were carried out off Northeast Brazil during austral spring 2015 and fall 2017, periods that we show to be representative of typical conditions for the spring and fall seasons. Using conductivity temperature depth oxygen probe and ship-mounted acoustic Doppler current profiler measurements, altimetry data, and numerical reanalysis products, we examine the spatiotemporal variability of the NBUC, providing a comprehensive view of the circulation, including NBUC-NBC transition and the potential impact of mesoscale eddies. The NBUC originating south of 10°S flows equatorward over the continental slope. NBUC mean velocity, transport and vertical extent of the velocity core were higher in spring 2015 (0.81 m s-1, 15.6 Sv, and >400 m) than in fall 2017 (0.65 m s-1, 11.0 Sv, and ∼300 m). The upper limit of the NBUC velocity core rose slightly from 160 m at 9°S to 105 m depth at 6°S. This pattern is associated with a northward increase in current velocity from 0.7 m s−1 at 9°S to 1 m s−1 at 5°S. The orographic effect shifts the flow from northeastward south of 7.5°S to northwestward north of 7.5°S, following the shoreline. Besides, altimetry data show that this flow can be locally influenced by mesoscale activity. Farther north, at ∼4.8°S, data obtained in fall 2017 show that the central branch of the South Equatorial Current (cSEC) enters into the western boundary system where it coalesces with the NBUC to form the NBC, flowing toward the Caribbean Sea. Finally, the NBUC retroflection does not feed the South Equatorial Undercurrent (SEUC), which, instead originates from retroflections of the cSEC and the equatorial branch of the South Equatorial Current (eSEC). PY 2021 PD JAN SO Progress In Oceanography SN 0079-6611 PU Elsevier BV VL 190 UT 000604185400001 DI 10.1016/j.pocean.2020.102475 ID 77143 ER EF