Recent progress in understanding physical and chemical properties of mineral dust

Abstract

This paper presents a review of recently acquired knowledge of the physico-chemical properties of mineral dust from Africa and Asia based on data and discussion during the Third International Dust Workshop, held in Leipzig (Germany) in September 2008. Various regional experiments have been conducted in the last few years, mostly close to source regions or after short-range transport. Significant progress has been made in characterising the mineralogy of iron and the description of particle shape close to source regions. We consider that future research should focus on the evolution of dust properties during transport. In particular, the prediction of the characteristics of the size distribution of mineral dust at emission and their dynamics evolution during transport should be considered as a high-priority. The presence of large airborne particles above 20 μm in diameter, suggested by various studies, has limited implication for radiation, but should be important for deposition-based studies such as those on ocean productivity. Modelling the uplifting and transport of such large particles will represent a new serious challenge for transport models. A critical assessment and standardisation of the experimental and analytical methods is recommended

Ground-based off-line aerosol measurements at Praia, Cape Verde, during the Saharan Mineral Dust Experiment: microphysical properties and mineralogy

“…The mineralogical composition revealed kaolinite as the dominating clay mineral. In comparison with measurements in Morocco (Kandler et al, 2009), this clearly reflects the difference in source regions for both locations (Caquineau et al, 1998; Formenti et al, 2010). The mineralogical measurements also confirmed that the aerosol during the three dust periods was composed—within experimental errors—of the same components.…”

The 7–13 March 2006 major Saharan outbreak: Multiproxy characterization of mineral dust deposited on the West African margin

“…Thus, more kaolinite is expected to be found in the Sahelian band [ Caquineau et al , 1998], which was subjected to a higher precipitation regime (summer West African monsoon) during the Quaternary. Southern Saharan and Sahelian regions are thus typified by low I/K ratios (typically <0.5) as well as by particularly low amounts of palygorskite [ Scheuvens et al , 2009; Formenti et al , 2010], which both characterize the end of the March 2006 event.…”

Airborne observations of mineral dust over western Africa in the summer Monsoon season: spatial and vertical variability of physico-chemical and optical properties

“…The comparison of size distribution of mineral dust from one study to the other is a difficult task which depends also critically on the sampling method (Reid et al, 2003;Formenti et al, 2010). As a general remark, the analysis of airborne published results suggests that the SAMUM-based size distributions ) have a more pronounced coarse mode than those from the AMMA SOP-0/DABEX and DODO campaigns .…”