Extended Data Fig. 3: Diurnal cycles of ions for station measurements.

Separated by NPF and non-NPF days, for (a) oxygenated organics, containing C₅ and C₆ oxygenated organics, (b) dicarboxylic acids, (c) iodic acid, (d) methanesulphonic acid, and (e) SO₃^- and SO₅^- ions. Shaded regions show 95% confidence regions on the mean.