An additional low layer transport of Sahelian and Saharan dust over the north‐eastern Tropical Atlantic

Abstract

Mineral dust concentrations have been measured from a monitoring aerosol station set up at Sal, Cape Verde Island between December 1991 and December 1994 in order to assess the transport process of African dust over the North‐eastern Tropical Atlantic. These measurements indicate a pronounced seasonal pattern, with maximum dust concentrations observed during winter. A meteorological analysis shows that the transport of dust occurs at low altitudes, in the trade winds layer, during this season. Large quantities of dust are carried out of North‐western Africa, in particular from the Sahel at these altitudes. Such process could constitute the major supply of atmospheric mineral matter to the surface sea water of the Eastern Atlantic.

Comparison of CALIPSO aerosol optical depth retrievals to AERONET measurements, and a climatology for the lidar ratio of dust

“…One item worth mentioning is that dust is located at high altitudes (1.5-7 km) over the Atlantic Ocean in the summer months (Prospero and Carlson, 1972;Chiapello et al, 1995Chiapello et al, , 1997Karyampudi et al, 1999;Kaufman et al, 2005), and may be located above pollution or marine aerosols without much interstitial mixing of other aerosol species. Indeed, Ridley et al (2012) shows seasonally averaged CALIOP extinction profiles over Africa and the Atlantic, and there is always significant extinction below the Sahran aerosol layer.…”

Desert dust impacts on human health: an alarming worldwide reality and a need for studies in West Africa

“…Three main trajectories of dust from the Saharan source area are distinguished ). The first is over thousands of kilometres and crosses the Atlantic Ocean to the United States, the Caribbean and South America (Chiapello et al 1995;Kellogg et al 2004); the second carries dust to the Mediterranean and Europe (Kellogg et al 2004;Perez et al 2008); and the third transports dust to the eastern Mediterranean and the Middle East (Kubilay et al 2003;Middleton et al 2008). Each of these trajectories can be seen at a specific period of the year, with intensity varying annually .…”

Transport of airborne lithogenic material down through the water column in two contrasting regions of the eastern subtropical North Atlantic Ocean

“…The upwelling system gives rise to a strong east-to-west decreasing gradient in primary productivity; ~260 g organic C m-2 yr-1 in the mesotrophic region and ~110 g organic C m -2 yr -l in the oligotrophic region [Morel, 1996], with much higher rates in eutrophic coastal waters (~535 g organic C m -2 yr-1 at the Eumeli' eutrophic site; see Figure 1). [Chiapello et al, 1995]). This cycle is driven by the lower atmospheric transport occurring within the continental trade winds (Harmattan) in winter.…”