Fig. 1. (a) Flight tracks of the sampling locations. (b–e) HYSPLIT analysis of the 4 day back trajectories of the air masses where the samples were taken. Each of the panels contains the samples collected in each of the four days of the campaign. The back trajectory associated with each air mass has been coloured based on its altitude. The stars correspond to the starting point of each back trajectory, which is the middle point of the sampling location.
