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Title: Airborne aerosol in situ measurements during TCAP: A closure study of total scattering

We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by a suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculatedmore » scattering, respectively.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Univ. of Nevada, Reno, NV (United States)
Publication Date:
OSTI Identifier:
1213372
Report Number(s):
BNL--108230-2015-JA
Journal ID: ISSN 2073-4433; R&D Project: 2016-BNL-EE630EECA-Budg; KP1701000
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Atmosphere (Basel)
Additional Journal Information:
Journal Name: Atmosphere (Basel); Journal Volume: 6; Journal Issue: 8; Journal ID: ISSN 2073-4433
Publisher:
MDPI
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Secretary of Energy (S)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES aircraft measurements of aerosol microphysical, chemical, and optical components and ambient relative humidity; Ultra-High Sensitivity Aerosol Spectrometer (UHSAS); Passive Cavity Aerosol Spectrometer (PCASP); Cloud and Aerosol Spectrometer (CAS); Aerosol Mass Spectrometer (AMS); Single Particle Soot Photometer (SP2); integrating nephelometer; humidification system; Two-Column Aerosol Project (TCAP)