Aerosol radiative forcing from spectral solar attenuation measurements due to aerosol loading using AERONET over pretoria in South Africa

This article reports the results obtained from sun-sky radiometer over a subtropical urban station Pretoria, South Africa from January to December, 2012. Detailed analysis revealed that, the monthly mean AOD₅₀₀ ranges from 0.10 to 0.34 with an annual mean of 0.19±0.09. The aerosol volume size distribution has shown a bimodal log-normal structure with a fine (coarse) mode maximum at a radius of 0.15 μm (5.0 μm). SSA showed a slight increase with increase in the wavelength during the summer and decreased dramatically with increased wavelength in the other seasons. The top of the atmosphere (TOA) forcing values for the study period is in the range -5 to -22 Wm^-2, and at the surface (BOA) from -23 to -50 Wm^-2.