Fig. 2: Global distribution of aerosol acidity at 950 mbar and vertical profiles of aqueous sulfate formation pathways average by latitude in 2019.

a, b January and c, d July. The pie sizes display the total rate of sulfate productions (average by latitude), and the pie colors represent the contributions from the corresponding formation pathways (H2O2, NO2, O3, and TMI). The colored dots to the right of the pies indicate the mean pH values at that latitude. The vertical profiles of formation pathways showed seasonal features and they were distinct at different atmospheric pressures. Source data are provided as a Source Data file.