Extended Data Fig. 4: NO₃^- CI-APi-ToF PMF results for 8 factors.

showing (a) diurnals, where shaded region shows 1 standard deviation on the mean, (b) time series, and (c) mass spectra per factor. Data included 300 peaks between 150 – 400 m/Q for 1 week of CI-APi-ToF data. Q/Q_exp for this solution = 1.004.