Mobile column measurements provide a means to characterize the distribution of trace gases over a large spatial scale while capturing the atmospheric variability over the column. Combined with wind measurements, mobile column measurements of trace gases can be used to constrain emission of trace gases from source regions. We have developed a mobile solar tracker to take advantage of the high photon flux available with direct sun observations to measure trace gas vertical columns with high precision from a mobile laboratory. The mobile tracker is an alt-azimuthal tracker featuring a motion compensation system and an imaging feedback loop. The motion compensation system provides the Euler angles of the mobile platform in real time to orient the tracker while the imaging feedback loop enables high precision tracking. The tracker can be simultaneously coupled to UV-Vis and FTIR spectrometers to measure trace gases such as nitrogen dioxide (NO2), glyoxal (CHOCHO), formaldehyde (HCHO), ethane (C2H6), and ammonia (NH3). It was deployed on several campaigns including in Northern Colorado during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) 2014 field campaign and the 2018 Biomass Burning Fluxes of Trace Gases and Aerosols (BB-FLUX) campaign in Idaho.
