Present Transport and Deposition Patterns of African Dusts to the North-Western Mediterranean

Abstract

The elements associated with mineral aerosol particles exhibit, in the Western Mediterranean, sporadic but intense concentration peaks. Twenty dust events were recorded during a one-year sampling period with their frequency being maximum in spring and summer. Threedimensional air-mass trajectories as well as satellite imagery (Meteosat II) show that all these events are associated with transport of so~l dust from Africa. Three principal source-regions have been distinguished by using air-mass trajectories. Each of them seems to be characterized also by the chemical composition of the dust collected in Corsica. Moreover, the emissions and transport of dust particles from these various source-regions were found to occur during different times of the year. This has been explained by the seasonal atmospheric circulation patterns over North Africa and the Western Mediterranean.Finally, total deposition measurements show that such dust transport events control a large fraction of the yearly atmospheric deposition of mineral aerosol particles to the Western Mediterranean. One single deposition event of short duration was found to account for 30% of the total annual flux for elements such as Si and Al. 227 M. Leinen and M. Sarnthein (eds.), Paleoclimatology and Paleometeorology: Modern and Past Patterns olGlobal Atmospheric Transport, 227-252.

Radiogenic isotopes for deciphering terrigenous input provenance in the western Mediterranean

“…In the case of the Mediterranean region, its proximity to the Sahara desert makes this area a key location for tracking terrigenous provenance and variations in source areas. In the western Mediterranean, the main sources of terrigenous material are the eolian fraction from arid and semiarid regions in North Africa, the suspended fluvial particles from the southwestern Europe and North African runoff, and the suspended particulate matter from the Atlantic and Mediterranean waters Bergametti et al, 1989aBergametti et al, , 1989bLoÿe-Pilot and Martin, 1996;Molinaroli, 1996, Prospero, 1996Stumpf et al, 2011). The Western Sahara dry land in North Africa is recognized as a major eolian dust source (Prospero, 1999;Goudie and Middleton, 2001;Stuut et al, 2009;Prospero and Mayol-Bracero, 2013).…”

“…Extrapolating this figure to the total western Mediterranean basin area (840,000 km 2 ) yields an average total atmospheric flux of 10.9  0.6 x 10 12 g/a (Bergametti et al, 1989a(Bergametti et al, , 1989bLoÿe-Pilot et al, 1989). The most important source areas of Saharan dust are located in the Western Sahara, Mauritania and Senegal, northern Mali, Atlas Mountains through Morocco, Algeria and Tunisia, central and eastern Libya, western Chad (Bodélé depression), southern Egypt, and northern Sudan (Molinaroli, 1996;Moreno et al, 2006;Laurent et al, 2008;Stuut et al, 2009;Scheuvens et al, 2013).…”

“…Furthermore, at the scale of Quaternary climatic oscillations, eolian dust fluxes to the ocean may have been higher during stadial (Greenland Stadial, GS) than interstadial periods (Greenland Interstadial, GI: nomenclature based on INTIMATE group, Lowe et al., 2008), as the result of a general southward displacement of the ITCZ during boreal summer (e.g., Reader et al, 1999;Elenga et al, 2000). At present, the relative amount of dust input from the Sahara and Sahelian regions to the western Mediterranean is low and occurs in winter (Bergametti et al, 1989b;Dulac et al, 1992), while in the eastern Mediterranean it is favored during stronger summer westerlies (Jilbert et al, 2010). The terrigenous particles deflated from the surface depend on several factors including wind speed, atmospheric instability, height of the source area, particle size, particle exposure, soil moisture, vegetative cover, and mineralogical composition (e.g., deMenocal, 1995deMenocal, , 2004Moreno et al, 2006;Mulitza et al, 2008).…”

Size resolved mass concentration and elemental composition of atmospheric aerosols over the Eastern Mediterranean area

“…Transport of Saharan dust occurs mostly during the spring and summer and causes sporadic crustal aerosol pulses to the Mediterranean area (e.g. Bergametti et al, 1989b;Moulin et al, 1998).…”

Asian Dust Storm as a Natural Source of Air Pollution in East Asia; its Nature, Aging and Extinction

“…The red rain, rain event carrying dust from Sahara desert, North African sources, are frequently falling with average frequency of around 3 events per year at Barcelona and surroundings in NE Spain 8). Red rains show a high load of dissolved ions (Rodà et al, 1993) and particulate matter (Berganetti et al, 1989). In Japan, a yellow rain, which is rain colored yellow by particulate matter with high pH value (6.35) due to the alkaline dust storm particles, was reported in the end of Mar.…”