Publication Date:
2022-05-25
Description:
Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 5134–5163, doi:10.1002/2015JC011468.
Description:
The pathways and physical mechanisms associated with intrusions of cold, nutrient-rich South Atlantic Central Water (SACW) on the continental shelf of the Espírito Santo Basin (ESB), off southeast Brazil (18°S–22°S), are investigated. To this end, a set of process-oriented, Primitive-Equation (PE) numerical models are used, together with an independent and more complete PE model, available observations and simple theoretical ideas. SACW enters the model ESB shelf mostly through two preferential pathways along the Tubarão Bight (TB, 19.5°S–22°S). These pathways are found to be locations where an equatorward along-isobath pressure gradient force (PGFy*) of inline image m s−2) develops in response to steady wind forcing. This equatorward PGFy* is essentially in geostrophic balance, inducing onshore flow across the shelf edge, and most of the shelf proper. The Brazil Current (BC) imparts an additional periodic (in the along-shelf direction) PGFy* on the shelf. The intrinsic pycnocline uplifting effect of the BC in making colder water available at the shelf edge is quantified. The BC also induces local intrusions by inertially overshooting the shelf edge, consistent with estimated Rossby numbers of inline image0.3–0.5. In addition, the planetary β-effect is related to a background equatorward PGFy*. A modified Arrested Topographic Wave model is shown to be a plausible rationalization for the shelf-wide spreading of the pressure field imparted by the BC at the shelf edge. The deep-ocean processes examined here are found to enhance the onshore transport of SACW, while wind forcing is found to dominate it at leading order.
Description:
The first author acknowledges support
from the S~ao Paulo Research
Foundation (Fundac¸~ao de Amparo a
Pesquisa do Estado de S~ao Paulo,
FAPESP), via grants 2013/11465–4 and
2014/03451–6. Kenneth Brink
acknowledges support from NSF
(grant OCE-1433953). Ilson da Silveira
acknowledges support from FAPESP
08/58101–9, CNPq 3071122/2010–7,
and CAPES 2201/2014. Wilton Arruda
acknowledges support from CNPq
(MCTI/CNPq/Universal 14/2014, grant
443162/2014–0), and from INCT–Mar–
COI, MCTI/CNPq grant 565062/2010–7.
Renato Martins acknowledges support
from Petr oleo Brasileiro S/A (AMBES
Project, PT–133.01.10636).
Description:
2017-01-30
Keywords:
Cross-shelf transport
;
Brazil current
;
Coastal dynamics
;
South Atlantic Central Water
;
Deep-ocean forcing
;
Arrested topographic wave
Repository Name:
Woods Hole Open Access Server
Type:
Article
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