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Title: 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 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.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [1] ;  [4] ;  [1] ; ORCiD logo [1] ;  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Univ. of Nevada, Reno, NV (United States). Dept. of Physic
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Univ. of Colorado, Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences (CIRES)
Publication Date:
Report Number(s):
BNL-205806-2018-JAAM
Journal ID: ISSN 2073-4433; ATMOCZ
Grant/Contract Number:
SC0012704; AC05-76RL01830
Type:
Accepted Manuscript
Journal Name:
Atmosphere (Basel)
Additional Journal Information:
Journal Name: Atmosphere (Basel); Journal Volume: 9; Journal Issue: 6; Journal ID: ISSN 2073-4433
Publisher:
MDPI
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1457346
Alternate Identifier(s):
OSTI ID: 1461809