From 7 June until 5 July 2013, BIRA-IASB participated in the "Multi Axis Doas - Comparison campaign for Aerosols and Trace gases" (MAD-CAT) at the Max Planck Institute (MPI) for Chemistry in Mainz, Germany. Members from over 10 research groups from all over the globe gathered and set up their instruments for an extensive comparison of measurements.The campaign aimed at the comparison of the different MAX-DOAS instruments in terms of Differential Slant Column Density (DSCD) and profile retrievals for several gases (such as NO₂, HCHO, H₂O, and O₄). Several specific aspects were studied in detail, such as the influence of cloud cover, the azimuth dependence, and the importance of elevation adjustments. For the study of azimuthal effects, the results were supplemented by daily mobile DOAS measurements taken at circular trajectories around Mainz. A detailed description of the measurement setup and strategy can be found here.

The BIRA-IASB MAX-DOAS instrument in Mainz	Car-mounted mobile DOAS instrument