Multi-axis-DOAS measurements of NO2 during the BAB II motorway emission campaign

Slant column densities (SCD) of traffic-generated NO2 were derived during the “BAB II” motorway emission campaign in April/May 2001 using scattered sunlight and a CCD-based Multi-Axis- (MAX) DOAS setup with eight viewing directions being probed simultaneously. The setup allowed for the tracking of the diurnal variation of a motorway plume with 1 min temporal resolution, an assessment of the vertical structure as well as the comparison with the plume outreach of Heidelberg.