Improving the Calculation of the Sulfate Aerosol Evolution and Radiative Effects in the Institute of Numerical Mathematics, Russian Academy of Sciences, Climate Model

Improvements in simulations of sulfate aerosol from natural dimethyl sulfide (DMS) emissions in the climate model of the Institute of Numerical Mathematics of the Russian Academy of Sciences (INM RAS) provide a better agreement between new model estimates of aerosol optical thickness (AOT) and the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis data. These data and the latest recommended emissions are used to estimate radiative forcing effects (RFEs) of the sulfate aerosol of different origin at the top of the atmosphere. The maximum (in absolute values) radiative effect of natural sulfate aerosol is observed due to high DMS emissions over the marine coast of Antarctica, where the annual mean RFE is –0.14 W m–2 (up to –0.45 W m–2 in January). For the 25°–45° N area, zonally averaged annual RFEs due to anthropogenic emissions exceed –0.7 W m–2. The average global annual RFE of sulfate aerosol for 2005 is –0.36 W m–2 and hardly changes at all by season. Overall, the fraction of the RFE from natural sulfate aerosol is 20%, but there are significant variations in this value from month to month, with a maximum in January, when this fraction reaches 37%.