Ultrahigh resolution FT-ICR MS data of long-range transported free tropospheric aerosol collected at the Pico Mountain Observatory in the Azores

This dataset and the methods used to obtain it were described in “Molecular and physical characteristics of aerosol at a remote marine free troposphere site: Implications for atmospheric aging” submitted to Atmospheric Chemistry and Physics in February 2018. Briefly, three long-range transported organic aerosol samples were analyzed using negative mode electrospray ionization Fourier transform ion cyclotron mass spectrometry (FT-ICR MS) with a mass resolving power of 400,000 (defined at m/z 400). FLEXPART retroplume simulations indicated that two of the samples (PMO-1 & PMO-3) were influenced by North American wildfire emissions transported in the free troposphere and one (PMO-2) by North American outflow transported within the marine boundary layer. The water-soluble organic aerosol samples were analyzed in duplicate recording 200 transient scans each. The transients were co-added using the Midas Co-Add tool and molecular formula assignments were done using Composer software (Sierra Analytics), as described in previous studies (Dzepina et al., 2015). The resulting molecular formula assignments underwent additional quality assurance (QA) data filtering to make sure the formula assignments were chemically reasonable with respect to O/C, hydrogen to carbon ratio (H/C), double bond equivalent (DBE), and absolute PPM error as described in the Supplemental Information of Putman et al. (2012). To produce the final data set for each sample, the replicates were aligned and only the molecular formulas found in both replicates after QA were retained. References Dzepina, K., Mazzoleni, C., Fialho, P., China, S., Zhang, B., Owen, R. C., Helmig, D., Hueber, J., Kumar, S., Perlinger, J. A., Kramer, L. J., Dziobak, M. P., Ampadu, M. T., Olsen, S., Wuebbles, D. J., and Mazzoleni, L. R.: Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with a long-range transported biomass burning plume, Atmos. Chem. Phys., 15(9), 5047–5068, doi:10.5194/acp-15-5047-2015, 2015. Putman, A. L., Offenberg, J. H., Fisseha, R., Kundu, S., Rahn, T. A. and Mazzoleni, L. R.: Ultrahigh-resolution FT-ICR mass spectrometry characterization of α-pinene ozonolysis SOA, Atmos. Env., 46, 164–172, doi:10.1016/j.atmosenv.2011.10.003, 2012