The formation mechanism and radiative effect of secondary organic aerosols

Secondary organic aerosol (SOA) is the largest component of global organic aerosol and plays a key role in determining the Earth’s radiation budget. A global chemistry model is developed to make SOA internally mixed with other aerosols based on the mechanism of formation, and includes a comprehensive organic nucleation scheme. Using an internal mixing state reduces the aerosol number, resulting in a large decrease in the cloud albedo effect of SOA. Organic nucleation is responsible for the decrease of 16% in the total radiative forcing associated with anthropogenic aerosols due to the change in the size distribution and number concentration of SOA. The radiative effect of SOA on cirrus clouds is estimated to be 0.31–0.35 W m− 2 using assumed and predicted size distributions. The formation mechanism of SOA is still needed to be improved according to the developing of experiments and measurements to reduce the uncertainty in the estimation of radiative effect of aerosols.