"Aerosol Properties and Chemical Apportionment of Aerosol Optical Depth" by Brian I. Magi, Peter V. Hobbs et al.

Chemistry and Physics Faculty Articles

Title

Aerosol Properties and Chemical Apportionment of Aerosol Optical Depth at Locations off the U.S. East Coast in July and August 2001

Authors

Brian I. Magi, University of Washington - Seattle Campus
Peter V. Hobbs, University of Washington - Seattle Campus
Thomas W. Kirchstetter, Lawrence Berkeley National Laboratory
Tihomir Novakov, Lawrence Berkeley National Laboratory
Dean A. Hegg, University of Washington - Seattle Campus
Song Gao, University of Washington - Seattle CampusFollow
Jens Redemann, Bay Area Environmental Research Institute
Beat Schmid, Bay Area Environmental Research Institute

Document Type

Article

Publication Date

4-2005

Publication Title

Journal of Atmospheric Science

Keywords

Aerosols, Atomizers, Light scattering, Reflection, Optics

ISSN

1520-0469

Volume

Issue/No.

First Page

919

Last Page

933

Abstract

Airborne in situ measurements of vertical profiles of the aerosol light scattering coefficient, light absorption coefficient, and single scattering albedo (ω₀) are presented for locations off the East Coast of the United States in July–August 2001. The profiles were obtained in relatively clean air, dominated by airflows that had passed over Canada and the Atlantic Ocean. Comparisons of aerosol optical depths (AODs) at 550 nm derived from airborne in situ and sun-photometer measurements agree, on average, to within 0.034 ± 0.021. A frequency distribution of ω₀ measured in the atmospheric boundary layer off the coast yields an average value of ω₀ = 0.96 ± 0.03 at 550 nm. Values for the mass scattering efficiencies of sulfate and total carbon (organic and black carbon) derived from a multiple linear regression are 6.0 ± 1.0 m² (g SO⁼₄)⁻¹ and 2.6 ± 0.9 m² (g C)⁻¹, respectively. Measurements of sulfate and total carbon mass concentrations are used to estimate the contributions of these two major components of the submicron aerosol to the AOD. Mean percentage contributions to the AOD from sulfate, total carbon, condensed water, and absorbing aerosols are 38% ± 8%, 26% ± 9%, 32% ± 9%, and 4% ± 2%, respectively. The sensitivity of the above results to the assumed values of the hygroscopic growth factors for the particles are examined and it is found that, although the AOD derived from the in situ measurements can vary by as much as 20%, the average value of ω₀ is not changed significantly. The results are compared with those obtained in the same region in 1996 under more polluted conditions.

Comments

Additional Comments

NASA grant #s: NAGS-10745, NAGS-11665

NSUWorks Citation

Magi, B. I., Hobbs, P. V., Kirchstetter, T. W., Novakov, T., Hegg, D. A., Gao, S., Redemann, J., & Schmid, B. (2005). Aerosol Properties and Chemical Apportionment of Aerosol Optical Depth at Locations off the U.S. East Coast in July and August 2001. Journal of Atmospheric Science, 62, (4), 919 - 933. https://doi.org/10.1175/JAS3263.1. Retrieved from https://nsuworks.nova.edu/cnso_chemphys_facarticles/150

DOI

10.1175/JAS3263.1

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