Seasonal provenance changes in present-day Saharan dust collected in and off Mauritania
Friese, C.A.; van Hateren, J.A.; Vogt, C.; Fischer, G.; Stuut, J.-B.W. (2017). Seasonal provenance changes in present-day Saharan dust collected in and off Mauritania. Atmos. Chem. Phys. 17: 10163-10193. https://dx.doi.org/10.5194/acp-2017-131 In: Atmospheric Chemistry and Physics. Copernicus Publ: Göttingen. ISSN 1680-7316; e-ISSN 1680-7324, more |   |
| Authors | | Top | - Friese, C.A.
- van Hateren, J.A.
- Vogt, C.
| - Fischer, G.
- Stuut, J.-B.W., more
| |
| Abstract | Saharan dust has a crucial influence on the earthclimate system and its emission, transport and deposition areintimately related to, e.g., wind speed, precipitation, temperatureand vegetation cover. The alteration in the physical andchemical properties of Saharan dust due to environmentalchanges is often used to reconstruct the climate of the past.However, to better interpret possible climate changes the dustsource regions need to be known. By analysing the mineralogicalcomposition of transported or deposited dust, potentialdust source areas can be inferred. Summer dust transportoff northwest Africa occurs in the Saharan air layer (SAL).In continental dust source areas, dust is also transported inthe SAL; however, the predominant dust input occurs fromnearby dust sources with the low-level trade winds. Hence,the source regions and related mineralogical tracers differwith season and sampling location. To test this, dust collectedin traps onshore and in oceanic sediment traps off Mauritaniaduring 2013 to 2015 was analysed. Meteorological data,particle-size distributions, back-trajectory and mineralogicalanalyses were compared to derive the dust provenance anddispersal. For the onshore dust samples, the source regionsvaried according to the seasonal changes in trade-wind direction.Gibbsite and dolomite indicated a Western Saharanand local source during summer, while chlorite, serpentineand rutile indicated a source in Mauritania and Mali duringwinter. In contrast, for the samples that were collected offshore,dust sources varied according to the seasonal changein the dust transporting air layer. In summer, dust was transportedin the SAL from Mauritania, Mali and Libya as indicatedby ferroglaucophane and zeolite. In winter, dust wastransported with the trades fromWestern Sahara as indicatedby, e.g., fluellite. |
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