Figure 4. Modelled influence on global CCN of different organic growth rates from 1.7 nm to 3 nm simulated by the GLOMAP aerosol model.
a, The annual mean number concentration of soluble particles of at least 100 nm diameter (N100 on colour scale, taken as a proxy for CCN) at cloud base level. We treat irreversible (collision-limited) condensation of sulfuric acid for particle growth from 1.7 nm to 3 nm, together with a size-dependent growth rate due to HOMs from the present work. b, The percentage change in CCN concentration (colour scale) when growth from 1.7 nm to 3 nm is due to sulfuric acid alone. c, The percentage change in CCN concentration when we parameterize growth from 1.7 nm to 3 nm as irreversible condensation of sulfuric acid together with an organic contribution following ref. 30, which assumes a Kelvin barrier to organic condensation below 2.5 nm. All simulations assume the same nucleation rates at 1.7 nm and the same particle growth rates above 3 nm.