Geographical distribution and geomorphological characteristics of major global dust source areas

Satellite measurements provide useful information on mineral aerosol content of the atmosphere and on distribution of dust source regions. The NASA Total Ozone Mapping Spectrometer’s (TOMS) and Ozone Monitoring Instrument’s (OMI) Aerosol Index measurements (on board of different sun-synchronous satellites) have the longest (since November 1978) available global record with appropriate spatial (1×1.25 and 1×1 degree) and temporal (daily) resolution. The data-matrix was analysed by a self-developed mathematical-statistical MATLAB algorithm to attain information on situation and inter-annual and seasonal activity of major dust hot-spot areas.

The compiled average aerosol maps show that the most important sources are situated mainly in the desert, semi-desert regions of North Africa, Middle East and Central Asia creating a more or less continuous area, called “Global Dust Belt”. The frequency and magnitude of dust emission outside the dust belt is relatively low, and is concentrated in small distinct areas. In general, the temporal activity of source regions has an obvious seasonal pattern with a spring-summer maximum.

Based on the systematic analyses of geographical distribution, it can be stated that major sources are associated to specific geomorphological environments. These can be connected to geomorpholocial depressions, ephemeral streams or wadi-systems and to alluvial fans. The fine-grained material of most of the sources was accumulated in some kind of fluvial or lacustrine environment with a certain Pleistocene pluvial history, which acts as a dust source area after the desiccation.

Figure 1. Global mean map of the measured daily Aerosol Index values and locations of the discussed major dust source domains (modified after VARGA, GY. 2012). The investigated dust hot-spots are the followings: 1. North Africa: 1.1. Bodélé Depression; 1.2. Azawagh Structural Basin; 1.3. Taoudenni Basin; 1.4. W-Saharan sebkhas; 1.5. Tidikelt Depression; alluvial fans and wadis of W/NW-Ahaggar; 1.6. Chott Melrhir and Chott Jerid; 1.7. Cyreneica és a Quattara Depression; 1.8. Western escarpments of River Nile; 1.9. Tokar Delta; 2. SW Asia: 2.1. Salt flats and ephemeral streams of Jebel Tuwaiq; 2.2. Sabkha system of Jebel Dhoraf; 2.3. Floodplains deposits and marshlands of Tigris and Euphrates Basin; 3. Central Asia: 3.1. Sistan (Seistan) Basin; 3.2. Dasht-e Kavir and Dasth-e Lut; 3.3. Fergana Basin; 3.4. Kara-Bogaz Gol; 3.5. Aral Sea; 3.6. Alluvial deposits of Balkhas-Alakol Basin; 3.7. Junggar Basin; 3.8. Uvs Lake Basin; 3.9. Tarim Basin; 3.10. Salt flat of Lop Nor and Quaidam Basin; 3.12. Thar; 4. North America: 4.1. Salt flats at Great Salt Lake; 4.2. Smoke Creek and Black Rock Deserts; 4.3. Playa system of Salton Sink; 4.4. Chihuahuan Desert; 4.5. Bolsón de Mapimí; 5. South America: 5.1. Salar de Uyuni (and other salt lakes/salars of the Altiplano); 5.2. Eastern slopes of Southern Andes; 5.3. Patagonia; 6. South Africa: 6.1. Etosha Pan; 6.2. Makgadikgadi Depression; 7. Australia: 7.1. Lake Eyre Basin; 7.2. Floodplain deposits and salt swamps along River Darling (e.g. Caryapundy); 7.3. Floodplain deposits and salt swamps along River Murray; 7.4. Barkly Tableland. 

Full paper: Varga, Gy., Bradák, B., Szeberényi, J. (2014). Geographical distribution and geomorphological characteristics of major global dust source areas. In: Jakab, G., Szalai, Z. (Eds.) Talajpusztulás térben és időben: az "Eróziós kerekasztal 2013" közleményei. pp. 40–46.