Measurements were conducted near Kalamazoo, MI (42.2784°N, 85.6105°W) as part of the 2018 SNow and Atmospheric Chemistry at Kalamazoo (SNACK) campaign.The study was conducted from January 20 to February 24, 2018, at Western Michigan University in Kalamazoo, MI, USA.PM2.5 chloride and nitrate were measured at 1.8 m above ground level using an an ambient ion monitor-ion chromatography instrument (AIM-IC; model 9000D, URG Corp.)

LiF was used as an internal standard during field measurements. Offline calibrations, relative to LiF, were performed after the campaign using solutions of known concentrations (Markovic et al 2012, doi:10.1039/c2em00004k, and Chen et al 2019, doi:10.1021/acsearthspacechem.9b00023).AIM-IC has 3 h time resolution. Inorganic ion mass concentrations are given as micrograms per cubic meter.Gaps in the data represent periods where the instruments were not operational. Only ambient data is provided.