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BANINO: WTZ Southern Africa - SPACES II: BANINO - Benguela Ninos: Physical processes and long-period variability; Subproject: Interannual variability of wind-driven upwelling and at Benguela Ninos off Namibia

Off the coast of Angola and Namibia where the constant trade winds trigger the upwelling of cold water, it does occur that warm tropical waters episodically prograde far into the upwelling area causing drastic changes of environmental conditions. BANINO aims at a better understanding of the influence global change has on frequency and intensity of these so called Benguela Ninos.

The IOW part of BANINO supports this overall objective by a) reconstructing historical time series from the Benguela upwelling area and b) by measuring campaigns and modell studies. The latter serves to understand the variability of the hydrographical conditions and the related changes in the ecosystem like the oxygen conditions, the nutrient concentrations or the primary production.

For the reconstruction of historical data, we will use meteorological data from the isle of St. Helena covering a time span of more than a century. Together with long-term air pressure data from Gobabeb, Namibia, this will lead to a climate-index, which after correlation with water temperature anomalies will enable us to prolong the Benguela Nino time series into the past.

Model-based tracer experiments showed that the expansion of tropical warm water masses into the Benguela area does not only occurs via the Eastern Margin Currents, but also via several branches of the Atlantic equatorial current system. The project aims at a quantitative analysis for typical Benguela Nino periods.

To enhance the detection of regional impacts of climate change, we will drive the coupled ecosystem model of IOW with wind data from the Kiel climate model. This will result in a model data set covering the hydrographical and ecosystem conditions for the last 100 years.


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