Thursday, 12 November 2009
Several hundreds tons of Saharan dust is transported from Africa to the Atlantic Ocean every year. The prevailing winds carry massive amounts of Saharan dust out over the eastern Atlantic, often in association with African easterly waves. The Saharan Air Layer (SAL) is generated when hot, dry mineral-rich dust from the Sahara Desert comes into contact with the cool, moist marine air of the Atlantic Ocean. The SAL tends to suppress Tropical Cyclone (TC) activity by introducing dry, stable air into the storm, causing the vertical wind shear to increase and enhanced temperature inversion. Or, the SAL may enhance TC activity by acting as cloud-nucleating aerosol on the TC development. It is shown that the SAL can be moved to mesoscale convective systems and, later on, may develop TCs. Dust coated with soluble materials, such as sulfur, may affect the TC development as cloud condensation nuclei. However, this additional role of the SAL as cloud-nucleating aerosol on the storm development is still not well understood. To investigate the effect of soluble materials such as heavy metals on Saharan dust, the sorption capacity of lead (Pb) has been measured on soil mixtures of SiO2 (49.3%) and Na2O (4.4%) using UV-vis spectrometer. The sorption curve of lead solutions and the radius of the insoluble core of the soil-driven dust particulates will be provided.
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