Response of the Benguela upwelling systems to spatial variations in the wind stress

Fennel, Wolfgang; Junker, Tim; Schmidt, Martin; Mohrholz, Volker

doi:10.1016/j.csr.2012.06.004

Cited by 50 publications

(70 citation statements)

References 16 publications

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“…The existence of SACW on the southwest African shelf up to 27°S was demonstrated by field observations and numerical simulations, e.g. Gordon et al (1995) and Fennel et al (2012). The other central water mass, the Eastern South Atlantic Central Water (ESACW), enters the BUS from the region of the Cape of Good Hope, Poole and Tomczak (1999).…”

Section: Introductionmentioning

confidence: 97%

The relation of wind stress curl and meridional transport in the Benguela upwelling system

Junker

Schmidt

Mohrholz

2015

Journal of Marine Systems

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Section: Introductionmentioning

confidence: 97%

The relation of wind stress curl and meridional transport in the Benguela upwelling system

Junker

Schmidt

Mohrholz

2015

Journal of Marine Systems

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“…Thermocline perturbations in the west-central equatorial Atlantic propagate as Kelvin Waves eastward and southward along the Equator and then southward along the western African coastline; these outcrop in the ABFZ when they meet the upward sloping isotherms of the Benguela upwelling system . The ABFZ is also sensitive to local winds, in particular, the Benguela low-level coastal jet (e.g., Fennel et al 2012;Patricola and Chang 2016) and the associated local wind stress curl biases can explain the SST bias (Colberg and Reason 2006;Xu et al 2014;Grodsky et al 2012). These local errors were also linked to the South Atlantic Anti-cyclone, and could be enhanced by ocean-atmosphere coupling (Cabos et al 2016).…”

Section: Introductionmentioning

confidence: 98%

Causes of the large warm bias in the Angola–Benguela Frontal Zone in the Norwegian Earth System Model

et al. 2017

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simulation). There is no evidence that local air-sea feedbacks among wind stress curl, SST, and sea level pressure (SLP) affect the ABFZ SST bias. Turbulent surface heat flux differences between coupled and uncoupled experiments explain the remaining 2 °C warm SST bias in NorESM. Ocean circulation, upwelling and turbulent heat flux errors all modulate the intensity and the seasonality of the ABFZ errors.

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“…Before it veers offshore, the atmospheric lowlevel coastal jet has a quasi-permanent northern maximum located at about 17.5°S that coincides with the Cunene upwelling cell (Lutjeharms and Meeuwis 1987;Patricola and Chang 2017). This maximum is related to a maximum in negative wind stress curl between 15° and 20°S, which is considered to be the main driving mechanism for poleward flow along the eastern boundaries (e.g., McCreary and Chao 1985;Marchesiello et al 2003;Fennel et al 2012;Junker et al 2015).…”

Section: History Of Physical Oceanography In Angolamentioning

confidence: 99%

“…Besides equatorial wave forcing, theoretical, modeling, and observational studies have shown that local wind forcing plays an important role in setting the structure and driving the variability of the eastern boundary circulation in upwelling regions, including the Benguela upwelling (McCreary and Chao 1985;Marchesiello et al 2003;Fennel et al 2012;Junker et al 2015;Small et al 2015). In particular, the southern Angola region and the Benguela upwelling to the south are impacted by strong southerly surface winds associated with the Benguela atmospheric low-level coastal jet (e.g., Nicholson 2010; Patricola and Chang 2017).…”

Section: History Of Physical Oceanography In Angolamentioning

confidence: 99%

Eastern Boundary Circulation and Hydrography Off Angola: Building Angolan Oceanographic Capacities

Tchipalanga

Dengler

Brandt

et al. 2018

Bulletin of the American Meteorological Society

122

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The eastern boundary region off Angola encompasses a highly productive ecosystem important for the food security of the coastal population. The fish-stock distribution, however, undergoes large variability on intraseasonal, interannual, and longer time scales. These fluctuations are partly associated with large-scale warm anomalies that are often forced remotely from the equatorial Atlantic and propagate southward, reaching the Benguela upwelling off Namibia. Such warm events, named Benguela Niños, occurred in 1995 and in 2011. Here we present results from an underexplored extensive in situ dataset that was analyzed in the framework of a capacity-strengthening effort. The dataset was acquired within the Nansen Programme executed by the Food and Agriculture Organization of the United Nations and funded by the Norwegian government. It consists of hydrographic and velocity data from the Angolan continental margin acquired biannually during the main downwelling and upwelling seasons over more than 20 years. The mean seasonal changes of the Angola Current from 6° to 17°S are presented. During austral summer the southward Angola Current is concentrated in the upper 150 m. It strengthens from north to south, reaching a velocity maximum just north of the Angola Benguela Front. During austral winter the Angola Current is weaker, but deeper reaching. While the southward strengthening of the Angola Current can be related to the wind forcing, its seasonal variability is most likely explained by coastally trapped waves. On interannual time scales, the hydrographic data reveal remarkable variability in subsurface upper-ocean heat content. In particular, the 2011 Benguela Niño was preceded by a strong subsurface warming of about 2 years’ duration.

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Response of the Benguela upwelling systems to spatial variations in the wind stress

Cited by 50 publications

References 16 publications

The relation of wind stress curl and meridional transport in the Benguela upwelling system

The relation of wind stress curl and meridional transport in the Benguela upwelling system

Causes of the large warm bias in the Angola–Benguela Frontal Zone in the Norwegian Earth System Model

Eastern Boundary Circulation and Hydrography Off Angola: Building Angolan Oceanographic Capacities

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