The Ion and Charged Aerosol Growth Enhancement (ION-CAGE) code: a numerical model for the growth of charged and neutral aerosols

The presence of small ions influences the growth dynamics of a size distribution of aerosols. Specifically the often neglected mass of small ions influences the aerosol growth rate, which may be important for terrestrial cloud formation. To this end, we develop a numerical model to calculate the growth of a species of aerosols in the presence of charge, which explicitly includes terms for ion-condensation. It is shown that a positive contribution to aerosol growth rate is obtained by increasing the ion-pair concentration through this effect, consistent with recent experimental findings. The ion-condensation effect is then compared to aerosol growth from charged aerosol coagulation, which is seen to be independent of ion-pair concentration. The model source code is made available through a public repository.