Real-time atmospheric measurements were made on board the CCGS Amundsen. Sampling lines were placed on the forward mast of the ship, and instruments were housed in a sampling shed located on the top deck. Mixing ratios of volatile organic compounds (VOCs: dimethylsulfide, acetone, methanol, benzene, etc.) were measured using proton-transfer-reaction mass spectrometry. Aerosol size distributions between 10 and 500 nm were measured using a scanning mobility particle sizer and total aerosol number concentrations > 3 nm were measured using an ultrafine condensation particle counter. All data have time resolution of minutes.

Membrane inlet mass spectrometer (MIMS) and optode / gas tension device (GTD) gas systems were deployed on the CCGS Amundsen in 2018 and 2019. These autonomous sensors obtained measurements of dissolved O2, Ar, and N2 from the ship's underway seawater supply line at approximately 10-20 sec. intervals (<100 m spatial resolution). Raw and calibrated absolute gas concentrations, supersaturation anomalies, and gas ratios are reported. Data from the underway gas instrumentation were combined with hydrographic observations of surface and depth-resolved temperature and salinity (obtained by the Amundsen Science research group) collected via underway thermosalinograph (TSG) and Rosette-mounted conductivity-temperature-depth (CTD) instrumentation.