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Abstract
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Article Information:
Rising Dust Aerosol Pollution at Ilorin in the Sub-sahel Inferred from 10-year Aeronet Data: Possible Links to Persisting Drought Conditions
Okey K. Nwofor
Corresponding Author: Okey K. Nwofor
Submitted: 2010 July, 06
Accepted: 2010 August, 13
Published: 2010 October, 05 |
Abstract:
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AERONET Aerosol Optical Depth (AOD) and A ngstrom Exponent (α) data of Ilorin in the sub-
Sahel region of Nigeria (8º32'N; 4º34'E) for the first 10 years of measurements (April 1998-April 2008) are
analyzed with the aim of deducing recent trends in dust aerosol loading in the area. The data indicates averagely
increasing trends in AOD for both the dry and wet seasons. Analysis of the α data for two halves (1998-2002/03
and 2003-2007/08) of the progressive 10-year data span (1998-2008) reveals a slight increase (of ~ 8%) in the
probability density of the dominant mode of the sm aller α (α<1) fraction (associated w ith dust aerosols) in the
second part (2003-2007/08) compared to its value in the first part (1998-2002/03). The α peak also shifted to
a lower value during the second half of the series suggesting increased coarseness of particles possibly due to
presence of more dust aerosols. Considering that Sahara dust and biomass burning aerosols are both usually
not significant in the wet season, the observed growing AOD trends in both seasons and then the α variability
pattern suggest possible intensification of local dust pollutions at the site within the 10 year period considered.
These possibilities are linked to the persistent long-term drought and resulting aridity of the area. Given a
scenario where aerosol loading might inhibit rainfall, as some studies suggest, a reciprocal (positive feedback)
action of the form; dust loading ↔ drought is probably intensifying in the area.
Key words: AERONET, atmospheric pollution, drought, dust aerosol, sub-Sahel, West Africa,
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Cite this Reference:
Okey K. Nwofor, . Rising Dust Aerosol Pollution at Ilorin in the Sub-sahel Inferred from 10-year Aeronet Data: Possible Links to Persisting Drought Conditions. Research Journal of Environmental and Earth Sciences, (4): Page No: 216-225.
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ISSN (Online): 2041-0492
ISSN (Print): 2041-0484 |
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