Fig. 4

Chemically-explicit model results show similar variability. GECKO-A modeling results with the dynamics of SOA compositional variability for α- or β-pinene daytime OH^• oxidation (“OH”) or nighttime NO₃^• oxidation with RO₂^• reacting predominantly with HO₂^• or NO₃^• (“HO₂”, “NO₃”). a, b Model results show the evolution of compositional variability over reaction time, with variability increasing or decreasing over time for comparisons with like versus differing precursors, respectively. Oxidant exposure values for each modeling experiment are shown in Supplementary Figure 21, and the evolution of gas- and particle-phase mass and elemental ratios in the modeling experiments are shown in Supplementary Figure 22. c Intra-run comparisons of fresh (5 min simulation time) versus aged (last two simulation time points) compounds in the gas-phase GECKO-A output show compositional variability within single simulations. Bars represent maximum and minimum values for distinct compound fractions