A100-02
A Global-Scale In Situ Dataset of Aerosol Properties from the Atmospheric Tomography Mission (ATom)
Thursday, 10 December 2020: 10:34
Virtual
Charles A Brock1, Agnieszka Kupc2, Christina Williamson3, Karl D Froyd4, Gregory P Schill4, Daniel M Murphy5, Jose L Jimenez6, Pedro Campuzano-Jost6, Bernadett Weinzierl7, Maximilian Dollner8, Joshua Peter Schwarz5, Joseph M Katich9, Jack E Dibb10, Rodney J Weber11, Linghan Zeng11, Glenn S Diskin12 and Thaopaul V Bui13, (1)NOAA Boulder, Boulder, CO, United States, (2)University of Vienna, Faculty of Physics, Vienna, Austria, (3)NOAA/CIRES, Boulder, United States, (4)NOAA/CIRES, Boulder, CO, United States, (5)NOAA Chemical Sciences Laboratory (CSL), Boulder, CO, United States, (6)University of Colorado at Boulder, Cooperative Institute for Research in Environmental Sciences (CIRES) and Department of Chemistry, Boulder, CO, United States, (7)University of Vienna, Faculty of Physics, Aerosol and Environmental Physics Group, Vienna, Austria, (8)Los Alamos, NM, United States, (9)University of Colorado Cooperative Institute for Research in Environmental Sciences (CIRES) at the NOAA Chemical Sciences Laboratory (CSL), Boulder, CO, United States, (10)University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Durham, NH, United States, (11)Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA, United States, (12)NASA Langley Research Ctr, Hampton, VA, United States, (13)NASA Ames Research Center, Moffett Field, CA, United States
Abstract:
Between August 2016 to May 2018, an instrumented DC-8 aircraft operated by NASA performed global-scale measurements of aerosol composition and size distribution. Nearly continuous vertical profiles were made between ~0.18 and ~12 km altitude as the aircraft flew over the central Pacific and Atlantic oceans from ~83
o N to ~86
o S latitude in each of four seasons. Dry aerosol size distributions and single particle and accumulation-mode bulk composition measurements were used to calculate size-dependent aerosol hygroscopicity and reconstruct ambient size distributions based on measured relative humidity. Coarse-mode size distribution measurements made with an underwing aerosol/cloud probe were added to these data to allow production of an ambient size distribution extending from 2.7 nm to 50 µm in diameter every one minute of flight.
From these hydrated size distributions we calculated ambient optical properties, including single scatter albedo, extinction and absorption coefficients, fine/coarse fractions of extinction, the scattering phase function, and the asymmetry parameter. By vertically integrating optical properties during each ascent or descent, aerosol optical depth (AOD) and absorption AOD for the troposphere were determined. AOD calculated from the in situ measurements agreed with direct AOD measurements from nearby AERONET stations within expected uncertainties. The contribution to AOD from sea-salt, dust, biomass burning, sulfate-organic mixtures, black carbon, brown carbon, and particulate water were determined for each profile location (roughly every 5 degrees of latitude). The concentrations of cloud condensation nuclei available at different supersaturations were also calculated. The data were averaged into broad airmass types, providing representative statistics that characterize the aerosol properties of the remote troposphere and mid- and high-latitude lower stratosphere. Aerosol properties from these regions will be discussed. There are marked differences in aerosol abundance and properties between the northern and southern hemispheres, as well as regionally. This unique dataset of ambient aerosol properties determined from in situ measurements provides powerful constraints for satellite remote sensing measurements and global chemistry-climate models.
