Ambient aerosol properties in the remote atmosphere from global-scale in situ measurements

Abstract. In situ measurements of aerosol microphysical, chemical, and optical properties were made during global-scale flights from 2016–2018 as part the Atmospheric Tomography Mission (ATom). The NASA DC-8 aircraft flew ? 84? N to 86? S latitude over Pacific, Atlantic, Arctic, Southern oceans while profiling nearly continuously between altitudes 160 m 12 km. These global circuits once each season. Particle size distributions measured in cabin at dry conditions with an underwing probe ambient combined bulk single-particle composition observations water vapor, pressure, temperature estimate hygroscopicity hygroscopic growth factors calculate relative humidity. reconstructed, composition-resolved used intensive extensive properties, including single-scatter albedo, asymmetry parameter, extinction, absorption, Ångström exponents, depth (AOD) several wavelengths, well cloud condensation nuclei (CCN) concentrations fixed supersaturations lognormal fits four modes. Dry extinction absorption compared direct measurements, AOD derived profiles was remotely sensed ground-based Aerosol Robotic Network (AERONET); this comparison showed no substantial bias. purpose work is describe methodology by which are estimated provide statistical descriptions characteristics different remote air mass types, examine contributions types masses, entry point ATom database. (dust, sea salt, biomass burning, etc.) generally align expectations based on location continental sources aerosols, salt dominating column most environments dust burning (BB) particles contributing substantially AOD, especially downwind African continent. Contributions BB aerosols also significant free troposphere North Pacific. Comparisons lognormally fitted distribution parameters values Optical Properties Aerosols Clouds (OPAC) database commonly models show differences mean diameters standard deviations for accumulation-mode coarse-mode dust. contrast, comparisons data previously published shipborne marine boundary layer general agreement. dataset resulting can be improve representation climate-relevant masses through output assumptions retrievals both satellite sensing.