Ambient concentrations of aerosol precursor vapor concentrations (sulfuric acid, methanesulfonic acid, and iodic acid) in 5-minute resolution measured by a nitrate chemical ionization mass spectrometer

This dataset contains ambient concentrations of aerosol precursor vapors measured in the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. The timeseries includes a full year of sulfuric acid (SA), methanesulfonic acid (MSA), and iodic acid (IA) concentrations retrieved at a time resolution of 5 minutes between October 2019 and September 2020. The data were collected using a nitrate chemical ionization mass spectrometer (NO3-CIMS) as described by Jokinen et al. (2012). The instrument was located in the Swiss container, which was placed on the starboard side of Polarstern's bow on the D-deck during the campaign (Shupe et al., 2022). The concentration retrievals were obtained by integrating peaks from the high-resolution mass spectra for each compound of interest (either as a deprotonated ion or as its corresponding cluster with nitrate), normalizing the result with the sum of charger ions (NO3-, HNO3NO3-, (HNO3)2NO3-), and multiplying by the calibration factor (6×109 molec·cm-3) obtained from a dedicated calibration using SA. Since the instrument calibration was only performed using SA, the concentrations of MSA and IA are low limit estimations. SA was determined by peaks at mass to charge ratios (m/z) of 96.9601 Th (HSO4-) and 159.9557 Th (H2SO4NO3-), MSA was determined by m/z peaks at 94.9808 Th (CH3SO3-) and 157.9765 Th (CH3SO3HNO3-), and IA was determined by m/z peaks at 174.8898 Th (IO3-) and 237.8854 Th (HIO3NO3-). Zero measurements were performed periodically by placing a filter on the inlet of the instrument to determine the detection limit for each individual species. The detection limits were calculated as μ + 3 × σ, where µ is the average concentration and σ is the standard deviation, both of which were evaluated during filter measurements. The resulting detection limits are 8.8e4, 1.5e5, and 5.5e4 molec·cm-3 for SA, MSA, and IA, respectively. The dataset includes flags to specify the data that are below the detection limit. The influence of local pollution from the research vessel and other logistic activities was identified by applying a pollution detection algorithm (Beck et al., 2022) to particle number concentrations from a condensation particle counter (CPC3025, TSI) that was also located in the Swiss container. Periods that were potentially affected by primary pollution are flagged in the dataset. The columns in the data file include the date and time in Coordinated Universal Time (UTC); the concentration of SA, MSA, and IA in molec·cm-3; a detection limit flag for each individual species (1 = below detection limit); and a local pollution flag where the data may have influence from the vessel and logistical activities (1 = pollution was detected).