Comparison of Intercontinental Aerosols: Desert and Monsoon-Influenced Regions

摘要

AIM: This research project was undertaken to compare the optical and physical properties of aerosols at the 0.440 μm, 0.675 μm, 0.870 μm and 1.020 μm spectral wavelengths between desert and monsoon-influenced regions. In this project, Zinder, one of the popular cities in the Republic of Niger and Beijing, the capital city of China were chosen to represent desert and monsoon- influenced regions respectively. Place and Duration of Study: Four years of Aerosol Optical Depth (AOD) data were extracted from level 2.0, the quality-assured almucantar version products of AERONET data, at both Beijing-CAMS (39.933°N, 116.317°E) and Zinder Airport (13.775°N, 8.984°E) between 2012 and 2015. Methodology: In this research project, physical and optical properties of aerosols were determined using Angstrom equations. Angstrom exponent, curvature, turbidity coefficient and spectral variation of the aerosols in Zinder Airport and Beijing-CAMS were calculated and the results were then compared. Both the physical and optical properties of the aerosols were determined from the calculated values. Results: The results obtained indicated that there were dominant coarse-mode aerosol particles in Zinder city, while fine-mode aerosol particles were found in Beijing. The results also showed that the overall Aerosol Optical Depth (AOD) in Zinder is higher than that of Beijing, but the atmosphere of Beijing was hazier than that of Zinder. Conclusion: The prevalence of coarse-mode particle sizes in Zinder was due to desert dust particles in the region, while the prevalence of fine-mode particles in Beijing was due to anthropogenic aerosol particle generation in the region, which may result from heavy industrialization in China. The higher aerosol loading in Zinder is responsible for absorbing light coming from the sun which, in turn, makes the atmosphere clear, while the lower aerosol loading in Beijing is responsible for scattering light coming from the sun, thereby obstructing the atmospheric visibility in the region.