Sensitivities of the absorptive partitioning model of secondary organic aerosol formation to the inclusion of water

Depending on the assumptions about the participation of water in absorptive partitioning, the prediction of the distribution of semi-volatile organic component between the gaseous and condensed phases is shown to be highly sensitive to the ambient relative humidity and the formulation of the partitioning model used. Further sensitivities to the assumed pre-existing particulate loading and to parameterised organic component non-ideality are explored and shown to contribute significantly to the variation in predicted secondary organic particulate loading.