Open AccessOptical Properties of Aerosol Particles over the Northeast Pacific
Author(s) -
Julia Marshall,
Ulrike Lohmann,
W. R. Leaitch,
N. C. Shantz,
L. Phinney,
D. Toom-Sauntry,
Sangeeta Sharma
Publication year - 2005
Publication title -
journal of applied meteorology
Language(s) - English
Resource type - Journals
eISSN - 1520-0450
pISSN - 0894-8763
DOI - 10.1175/jam2267.1
Subject(s) - nephelometer , aerosol , scattering , mie scattering , particle (ecology) , absorption (acoustics) , wavelength , particle size distribution , atmospheric sciences , sea salt , single scattering albedo , light scattering , environmental science , particle size , materials science , optics , physics , meteorology , chemistry , geology , oceanography
In July 2002, atmospheric aerosol measurements were conducted over the northeast Pacific Ocean as part of the Subarctic Ecosystem Response to Iron Enhancement Study (SERIES). The following aerosol quantities were measured: particle number size distribution, particle scattering and backscattering coefficients at three wavelengths, particle absorption coefficient at one wavelength, and size-segregated particle chemical composition. Using Mie theory to calculate the aerosol particle scattering and absorption coefficients from the size distribution and chemical measurements, closure with the measured optical coefficients is not attained. Discrepancies between the calculated and measured scattering and backscattering coefficients are largely a result of the fact that the nephelometer measures scattering only between 7° and 170°. Over 90% of the total scattering and 50% of the backscattering in this study was not measured by the nephelometer because of the missing forward-scattering (0°–7°) and backscattering (170°–180°) segments of the phase function. During this study the majority of the total scattering and backscattering in the marine boundary layer of this region was a result of coarse particles consisting almost entirely of sea salt.