Browsing by Author "Sunnu, Albert Kojo"

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    Characterization of the harmattan dust aerosol in central Ghana
    (1997) Sunnu, Albert Kojo
    Saharan dust transport over central Ghana in West Africa has been studied and the physical characteristics of the aeolian dust determined. The effects of the aeolian haze on some physical processes have also been discussed. Atmospheric dust during the 1995/96 Harmattan period has been sampled at Kumasi (6°40’N, 1o 34’W), at a height of 15 m above ground level using a HIAC/ROYCO 5250A automatic optical airborne particle counter. The dust particle number concentration ranges from about 9 - 24 particles/cm3 of air while the mass concentration or dust load varies between 14 .μg/m3 and 56 μg/m3. The mean, median, and geometric mean diameters of the dust particles are 1.11μ.m, 0.66 μm, and 0.87 μm respectively. The mode of the distribution is estimated at 0.55 μm. It is also estimated that the particles sampled have a settling velocity of 0.1 mm/s and that they are capable of being transported over a horizontal distance of about 300 km under moderate wind conditions. The availability of fine clay and silt in the Sahara Desert, the north-east trade winds and the movement of the Inter-Tropical Convergence Zone are important factors governing the wind transported dust over the West African region between November and March.