当前位置: X-MOL 学术Prog. Oceanogr. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Near-surface western boundary circulation off Northeast Brazil
Progress in Oceanography ( IF 4.1 ) Pub Date : 2021-01-01 , DOI: 10.1016/j.pocean.2020.102475
Alina N. Dossa , Alex C. Silva , Alexis Chaigneau , Gérard Eldin , Moacyr Araujo , Arnaud Bertrand

Abstract 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).

中文翻译:

巴西东北部近地表西部边界环流

摘要 在热带大西洋,巴西北部潜流(NBUC)和巴西北部海流(NBC)作为大西洋经向翻转环流的近地表北向路径具有重要作用。为了调查该地区近地表西部边界环流的经向演化,我们在 2015 年春季和 2017 年秋季在巴西东北部海域进行了两次调查,我们证明这两个时期代表了春季和秋季的典型条件。使用电导温度深度氧探头和船载声学多普勒电流剖面仪测量值、测高数据和数值再分析产品,我们检查了 NBUC 的时空变异性,提供了环流的全面视图,包括 NBUC-NBC 过渡和潜在影响中尺度涡旋。源自 10°S 以南的 NBUC 在大陆坡上向赤道流动。NBUC 平均速度、传输和速度核心的垂直范围在 2015 年春季(0.81 m s-1、15.6 Sv 和 >400 m)高于 2017 年秋季(0.65 m s-1、11.0 Sv 和~300 m) )。NBUC 速度核心的上限从 9°S 时的 160 m 略微上升到 6°S 时的 105 m。这种模式与水流速度从 9°S 时的 0.7 ms-1 到 5°S 时的 1 ms-1 向北增加有关。地形效应沿着海岸线将水流从 7.5°S 以南的东北向南转移到 7.5°S 以北的西北向北。此外,测高数据表明,这种流动可能会受到中尺度活动的局部影响。再往北,大约 4.8°S,2017 年秋季获得的数据显示,南赤道流的中央分支 (cSEC) 进入西部边界系统,在那里与 NBUC 合并形成 NBC,流向加勒比海。最后,NBUC 逆反射不供给南赤道潜流 (SEUC),而是源自 cSEC 和南赤道海流 (eSEC) 赤道分支的逆反射。
更新日期:2021-01-01
down
wechat
bug