Impact of dry intrusion events on the composition and mixing state of particles during the winter Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA)

Abstract. Long-range transport of continental emissions has a far-reaching influence over remote regions, resulting in substantial change the size, morphology, and composition local aerosol population cloud condensation nuclei (CCN) budget. Here, we investigate physicochemical properties atmospheric particles collected on board research aircraft flown Azores during winter 2018 Aerosol Cloud Experiment Eastern North Atlantic (ACE-ENA) campaign. Particles were within marine boundary layer (MBL) free troposphere (FT) after long-range episodes facilitated by dry intrusion (DI) events. Chemical physical individual investigated using complementary capabilities computer-controlled scanning electron microscopy X-ray spectromicroscopy to probe particle external internal mixing state characteristics. Furthermore, real-time measurements size distribution, concentration, back-trajectory calculations utilized help bring into context findings from offline analysis. While carbonaceous found be dominant type region, changes percent contribution organics across (i.e., mixing) shifted 68 % 43 MBL 92 46 FT samples DI This is counterbalanced increase inorganics 32 57 8 55 FT. The quantification organic volume fraction (OVF) derived spectromicroscopy, which relates multi-component particles, showed factor 2.06 ± 0.16 1.11 0.04 FT, respectively, among samples. We show that supplying OVF ?-Köhler equation can used as good approximation field-measured situ CCN concentrations. also report ? values ?MBL, non-DI=0.48 DI=0.41, while result ?FT, non-DI=0.36 DI=0.33, consistent with enhancements followed episodes. Our observations suggest entrainment sources alters region. work presented here provides field observation data inform models simulate eastern Atlantic.