Altitude aerosol measurements in central France: seasonality, sources and free‐troposphere/boundary layer segregation

Long-term and continuous measurements of aerosol chemical composition is essential to improve our understanding of the formation and transformation of aerosol particles in the atmosphere. Thanks to the recent developments of aerosol mass spectrometry, notably with the Aerosol Chemical Speciation Monitor (ACSM, Aerodyne; Frohlich et al., 2013; Ng et al., 2011), this information can be acquired over long periods of time with minimal intervention from the user. The ACSM is a robust tool that measures aerosol chemical properties of the aerosol with time resolutions ranging from 10 to 30 min. Global long-term ACSM data sets have recently been presented in the literature, including a 6-year study near Paris (France; Petit et al., 2015; Zhang et al., 2019), a 2-year study in the megacity of Beijing (China; Sun et al., 2018), and a 5-year study from Leipzig (Germany; Poulain et al., 2020). The measurements within Europe are mostly being performed within the framework of the ACTRIS infrastructure (Aerosols, Clouds, and Trace gases Research InfraStructure), and a growing database of these measurements is available via the EBAS database (http://ebas.nilu. no/). Pluri-annuel and multi seasonal studies provide an opportunity to study how aerosol particles concentrations and chemical signature evolves over time in response to different airmass sources and atmospheric changes. This information is useful for understanding transport and aging patterns and can also be used for the validation of atmospheric models. Similar to worldwide measurements at low altitudes (Jimenez et al., 2009; Zhang et al., 2007), organic species also dominate the PM1 mass concentrations at high altitudes (Zhou et al., 2019). Frohlich et al. (2015) at the Jungfraujoch station (JFJ, 3,580 m a.s.l), showed that organics were the dominant species, making