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Original Research Papers

Dust mobilization and aerosol transport from West Africa to Cape Verde—a meteorological overview of SAMUM-2

Authors:

Peter Knippertz ,

School of Earth & Environment, University of Leeds, GB
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Matthias Tesche,

Leibniz Institute for Tropospheric Research, DE
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Bernd Heinold,

School of Earth & Environment, University of Leeds, GB
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Konrad Kandler,

Institute for Applied Geosciences, Technical University Darmstadt, DE
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Carlos Toledano,

Group of Atmospheric Optics, Valladolid University, ES
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Michael Esselborn

European Southern Observatory, DE
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Abstract

The second field campaign of the SAharan Mineral dUst experiMent (SAMUM-2) was performed between 15 January and 14 February 2008 at the airport of Praia, Cape Verde, and provided valuable information to study the westward transport of Saharan dust and the mixing with biomass-burning smoke and sea-salt aerosol. Here lidar, meteorological, and particle measurements at Praia, together with operational analyses, trajectories, and satellite and synoptic station data are used to give an overview of the meteorological conditions and to place other SAMUM-2 measurements into a large-scale context. It is demonstrated that wintertime dust conditions at Cape Verde are closely related to the movement and intensification of mid-latitude high-pressure systems and the associated pressure gradients at their southern flanks. These cause dust emission over Mauritania, Mali, and Niger, and subsequent westward transport to Cape Verde within about 1–5 d. Dust emissions often peak around midday, suggesting a relation to daytime mixing of momentum from nocturnal low-level jets to the surface. The dust layer over Cape Verde is usually restricted to the lowest 1.5 km of the atmosphere. During periods with near-surface wind speeds about 5.5 ms−1, a maritime aerosol layer develops which often mixes with dust from above. On most days, the middle levels up to about 5 km additionally contain smoke that can be traced back to sources in southernWest Africa. Above this layer, clean air masses are transported to Cape Verde with the westerly flow at the southern side of the subtropical jet. The penetration of extra-tropical disturbances to low latitudes can bring troposphere-deep westerly flow and unusually clean conditions to the region.

How to Cite: Knippertz, P., Tesche, M., Heinold, B., Kandler, K., Toledano, C. and Esselborn, M., 2011. Dust mobilization and aerosol transport from West Africa to Cape Verde—a meteorological overview of SAMUM-2. Tellus B: Chemical and Physical Meteorology, 63(4), pp.430–447. DOI: http://doi.org/10.1111/j.1600-0889.2011.00544.x
  Published on 01 Jan 2011
 Accepted on 3 May 2011            Submitted on 26 Oct 2010

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