Upwelling processes along a western boundary current in the Abrolhos–Campos region of Brazil

Aguiar, A.L.; Cirano, Mauro; Pereira, Janini; Marta‐Almeida, Martinho

doi:10.1016/j.csr.2014.04.013

Cited by 55 publications

(36 citation statements)

References 42 publications

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“…Although deep‐ocean forcing mechanisms related to the BC seem to be relevant to coastal upwelling south of the ESB [ Calado et al ., ; Palóczy et al ., ], their effects within the ESB have only recently been examined by Aguiar et al . []. These authors performed diagnostic analyses of a realistic primitive‐equation numerical model to quantify the upwelling contributions from Ekman transport, Ekman pumping, encroaching of the BC onto the shelf, and cyclonic BC meandering.…”

Section: Introductionsupporting

confidence: 86%

Pathways and mechanisms of offshore water intrusions on the Espírito Santo Basin shelf (18°S–22°S, Brazil)

et al. 2016

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The pathways and physical mechanisms associated with intrusions of cold, nutrient-rich South Atlantic Central Water (SACW) on the continental shelf of the Espırito Santo Basin (ESB), off southeast Brazil (188S-228S), 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, 19.58S-228S). These pathways are found to be locations where an equatorward alongisobath pressure gradient force (PGF y* ) of Oð10 26 m s 22 ) develops in response to steady wind forcing. This equatorward PGF y* 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) PGF y* 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 %0.3-0.5. In addition, the planetary b-effect is related to a background equatorward PGF y* . 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.

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Section: Introductionsupporting

confidence: 86%

Pathways and mechanisms of offshore water intrusions on the Espírito Santo Basin shelf (18°S–22°S, Brazil)

et al. 2016

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“…The increased upwelling decreased the coastal sea level by 15 to 20 cm, partly driven by the cooling of the water column detected by the XBT data in December of 2009, which also increased the SSH gradient across the AX97 section and the meandering of the BC. The increased BC meandering may have caused a stationary eddy growth, as suggested by previous studies (e.g., Aguiar et al, ; Calado et al, ), which occupied the AX97 location for nearly 3 months and also contributed for the decreased sea level near the coast.…”

Section: Discussionmentioning

confidence: 51%

Long‐Term Monitoring of the Brazil Current Transport at 22°S From XBT and Altimetry Data: Seasonal, Interannual, and Extreme Variability

et al. 2019

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The seasonal and interannual variability of the Brazil Current (BC) at 22°S is examined using expendable bathythermograph (XBT) transect and satellite altimetry data from 1993 to 2017. The XBT‐based mean absolute geostrophic transport of the BC is estimated as 4.7 ± 1.9 Sv, with additional 0.9 ± 0.9 Sv along the shelf. The strong agreement between the absolute dynamic height and altimetric sea surface height is used in two methods to reconstruct a daily time series of the BC transport since 1993. The altimetry‐based methods can represent well the BC transport seasonal cycle, whereas the XBT‐based estimates are slightly aliased by the strong regional mesoscale variability. At interannual timescales, the BC transport is significantly correlated (r = 0.43) with the wind stress curl in the western half of the basin with a lag of 19 months, which is consistent with baroclinic adjustment timescales. Other sources of variability can be observed in a case study of the summer 2009/2010 event, which was characterized by strong sea surface temperature anomalies of approximately 3 °C. During the event, the BC reached 11 Sv for nearly 3 months, partly driven by an increased coastal upwelling from a cyclonic wind stress anomaly, a standing eddy along the section, and thermosteric anomalies that reached the offshore side of section in February. Heat anomalies were transported southward along the subtropical gyre following the BC path in a period of 2 months, which is consistent with advective timescales. Potential implications for extreme sea level and summer precipitation events in South America are discussed.

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“…The alongshelf bottom stress originates from the interaction between near-bottom currents caused by the wind-driven EAC flow, current encroachment, and eddy activity and a rugged bathymetry (e.g. Everett et al, 2014;Aguiar et al, 2014). It is associated with a cross-shelf transport of water, subsequent upwelling and nutrient transport toward the surface layer (Oke and Middleton, 2000).…”

Section: Bottom Stress Datamentioning

confidence: 99%

Is the East Australian Current causing a marine ecological hot-spot and an important fisheries near Fraser Island, Australia?

Brieva

Ribbe

Lemckert

2015

Estuarine, Coastal and Shelf Science

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The distributions of Chlorophyll-a (Chl-a) blooms near the Fraser Island continental shelf along the east coast of Australia were analysed for the period 2002-2012. The blooms were found to exhibit two distinct quasiclimatological patterns. The first pattern was a broad near-coast mid-shelf distribution that prevailed from about March to July each year. The second pattern was established due to re-occurring outer-shelf Chl-a blooms southeast of Fraser Island from about August to February. The outer-shelf Chl-a bloom concentration maxima appeared to be higher than those associated with the near coast pattern. Both distributions were found to be characterised by significant year-to-year variability in the number of total blooms, the length of blooms and the Chl-a bloom concentration maxima. The physical cause of the outer-shelf Chl-a concentration maxima was of particular interest, since this location overlaps with a region previously identified as a key eastern Australian marine ecological site and important fisheries. In this analysis, we found that the area also overlaps with a hot-spot in EAC-generated bottom layer stress, which appears to be the main driver of the "Southeast Fraser Island Upwelling System".

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Upwelling processes along a western boundary current in the Abrolhos–Campos region of Brazil

Cited by 55 publications

References 42 publications

Pathways and mechanisms of offshore water intrusions on the Espírito Santo Basin shelf (18°S–22°S, Brazil)

Pathways and mechanisms of offshore water intrusions on the Espírito Santo Basin shelf (18°S–22°S, Brazil)

Long‐Term Monitoring of the Brazil Current Transport at 22°S From XBT and Altimetry Data: Seasonal, Interannual, and Extreme Variability

Is the East Australian Current causing a marine ecological hot-spot and an important fisheries near Fraser Island, Australia?

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