Aerosols properties over desert influenced locations situated in four different continents

Abstract

This paper investigates aerosol properties (physical, optical and radiative) to understand the aerosol climatology (2008–17) over four Aerosol Robotic Network (AERONET) sites situated in different continents. For this purpose, the chosen sites are Jaipur, India in Asia, Ilorin, Nigeria in Africa, Birdsville, Queensland in Australia and White Sand, New Mexico in America. The higher AOD were found at Jaipur (AOD≈0.57; α = 0.38) during month of June and at Ilorin (AOD ≈ 1.12 and α ≈ 0.56), Africa during February. The value of SSA are also found higher i.e. 0.94 and 0.96 during the MAM over Jaipur and Ilorin respectively due to dominance of dust aerosols. Ilorin experiences the influence of harmattan winds from November to March and shows significant increase not only in coarse mode but also in fine particles fraction. While the remaining sites i.e. White Sand, America; and Birdsville, Australia are found relatively pristine based on monthly averaged AOD, AE (α) and SSA. The estimated direct radiative forcing using SBDART indicates that Ilorin and Jaipur sites in Africa-Asia exhibit much higher values of TOA and BOA as compared to White Sands and Birdsville in America-Australia. The annual averaged radiative forcing are estimated over Ilorin (38.38 ± 16.89 W m−2) and Jaipur (36 ± 8.34 W m−2). Similarly, high radiative forcing efficiency of 66.86 ± 16.69 W m−2 τ0.55nm−1 and 67.96 ± 20.46 W m−2 τ0.55nm−1 are calculated for Ilorin and Jaipur, respectively. The influence of emission differs in different continents i.e. Africa-Asia to America-Australia sites.