Trace gas and aerosol interactions in the fully coupled model of aerosol-chemistry-climate ECHAM5-HAMMOZ: 2. Impact of heterogeneous chemistry on the global aerosol distributions

We use the ECHAM5-HAMMOZ aerosol-chemistry-climate model to quantify the influence of trace gas–aerosol interactions on the regional and global distributions and optical properties of aerosols for present-day conditions. The model includes fully interactive simulations of gas phase and aerosol chemistry including a comprehensive set of heterogeneous reactions. We find that as a whole, the heterogeneous reactions have only a small effect on the ${SO}_{2}$ and sulfate burden because of competing effects. The uptake of ${SO}_{2}$ on dust and sea salt decreases the ${SO}_{2}$ concentrations while the decrease in OH (that results from the uptake of (${HO}_{2}$, ${N}_{2}{O}_{5}$, and ${O}_{3}$) tends to increase ${SO}_{2}$ (because of reduced oxidation). The sulfate formed in sea salt aerosols from ${SO}_{2}$ uptake accounts for 3.7 Tg(S) a−1 (5%) of the total sulfate production. Uptake and subsequent reaction of SO2 on mineral dust contributes to a small formation of sulfate (0.55 Tg(S) a−1,