A Closure Study of Total Scattering Using Airborne In Situ Measurements from the Winter Phase of TCAP

We examine the performance of our approach for calculating the total scattering coefficient of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our extended examination involves airborne in situ data collected by the U.S. Department of Energy’s (DOE) Gulf Stream 1 a...

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Bibliographic Details
Published in:Atmosphere
Main Authors: Kassianov, Evgueni, Berg, Larry, Pekour, Mikhail, Barnard, James, Chand, Duli, Comstock, Jennifer, Flynn, Connor, Sedlacek, Arthur, Shilling, John, Telg, Hagen, Tomlinson, Jason, Zelenyuk, Alla, Fast, Jerome
Language:unknown
Published: 2023
Subjects:
54 ENVIRONMENTAL SCIENCES
North Atlantic
Online Access:http://www.osti.gov/servlets/purl/1457346
https://www.osti.gov/biblio/1457346
https://doi.org/10.3390/atmos9060228
Description
Summary:We examine the performance of our approach for calculating the total scattering coefficient of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our extended examination involves airborne in situ data collected by the U.S. Department of Energy’s (DOE) Gulf Stream 1 aircraft during winter over Cape Cod and the western North Atlantic Ocean as part of the Two-Column Aerosol Project (TCAP). The particle population represented by the winter dataset, in contrast with its summer counterpart, contains more hygroscopic particles and particles with an enhanced ability to absorb sunlight due to the larger fraction of black carbon. Moreover, the winter observations are characterized by more frequent clouds and a larger fraction of super-micron particles. We calculate model total scattering coefficient at ambient conditions using size spectra measured by optical particle counters (OPCs) and ambient complex refractive index (RI) estimated from measured chemical composition and relative humidity (RH). We demonstrate that reasonable agreement (~20% on average) between the observed and calculated scattering can be obtained under subsaturated ambient conditions (RH < 80%) by applying both screening for clouds and chemical composition data for the RI-based correction of the OPC-derived size spectra.

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