NASA - National Aeronautics and Space Administration

Two instruments,a nucleation-mode aerosol size spectrometers (NMASS; Williamson et al., 2018), and an ultra-high sensitivity aerosol spectrometers (UHSAS; Kupc et al., 2018) comprise the AMP package for ACCLIP. The AMP package provides particle size distributions with up to one-second time resolution for dry aerosol particles between 0.003 and 1.5 µm in diameter. Details of methods, uncertainties, and data products from the AMP package are in Brock et al. (2019).

During ATom, the instruments were used to investigate how particles in the remote atmosphere influence climate by examining the origin of small particles in the remote atmosphere and their growth to sizes where they can affect clouds and the sources, characteristics, and distribution of soil dust and sea-spray particles, and 3) the importance long-range transport from human and natural sources on background aerosol properties.

HTS is composed of two instruments based on absorption of near-infrared laser radiation in high finesse optical cavities. A Picarro G2401-m analyzer based on wavelength-scanned cavity ring-down spectroscopy (CRDS) measures CO2, CH4, and CO concentrations at 2-second intervals. A Los Gatos 913-0014 EP analyzer based on off-axis integrated cavity output spectroscopy (ICOS) measures N2O and CO concentrations at 1-second intervals. Extensive modifications have been applied to these commercial analyzers for flight and include vibration isolation, temperature control, additional flow control and pumping capacity for high-altitude sampling, sample drying, and in-flight calibrations using WMO-traceable compressed gas standards to verify stable and accurate performance throughout the full DC-8 flight envelope.

The PFP whole air sampler provides a means of automated or manual filling of glass flasks, twelve per PFP. The sampler is designed to remove excess water vapor from the sampled air and compress it without contamination into ~1-liter volumes. These flasks are analyzed at the NOAA’s Global Monitoring Division laboratory for trace gasses and at  the INSTAR’s Staple Isotope Lab laboratory for isotopes of methane. More than 60 trace gases found in the global atmosphere can be measured at mole fractions that range from parts-per-million (10^-6), e.g., carbon dioxide, down to parts-per-quadrillion (10^-15), e.g., HFC-365mfc.  The chemical species monitored include N₂O, SF₆, H₂, CS₂, OCS, CO₂, CH₄, CO, CFCs, HCFCs, HFCs, Solvents, Methyl Halides, Hydrocarbons and Perfluorocarbons.