Open AccessEffects of atmospheric particles from Southern California on the optical properties of seawater
Author(s) -
Stramska Malgorzata,
Stramski Dariusz,
Cichocka Marta,
Cieplak Agnieszka,
Woźniak Sławomir B.
Publication year - 2008
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007jc004407
Subject(s) - aerosol , seawater , absorption (acoustics) , atmosphere (unit) , wavelength , radiative transfer , particulates , particle (ecology) , deposition (geology) , scattering , particle size distribution , particle size , attenuation , range (aeronautics) , atmospheric sciences , analytical chemistry (journal) , environmental science , materials science , chemistry , physics , environmental chemistry , optics , geology , meteorology , oceanography , organic chemistry , sediment , composite material , paleontology
The role of particles deposited from the atmosphere to the ocean is poorly understood in ocean optics. We examined the light absorption and scattering properties of atmospheric particulate matter, which was collected by dry deposition near the Pacific coastline in La Jolla, Southern California, and then suspended in particle‐free seawater for subsequent laboratory measurements. Within these suspensions, we measured the spectral absorption and beam attenuation coefficients, particle size distribution, and particle mass concentration of atmospheric particles. We also determined the 4‐week average aerosol deposition rates at the experimental site over a period of 9 months. The mass‐specific particle absorption a p *( λ ) and scattering b p *( λ ) coefficients showed considerable variability among the samples because of the variations in particle size distribution and composition. For example, a p *(440) was on average 0.042 m 2 g −1 but exhibited over fivefold range among the samples. At near‐infrared wavelengths (750–800 nm), the magnitude of a p * was significant (>0.02 m 2 g −1 for a number of samples) and is likely attributable to the presence of black carbon. The b p *( λ ) values were virtually wavelength‐independent because of the significant presence of relatively large particles (>10 μ m) in our samples. The magnitude of b p *( λ ) varied within a 3.5‐fold range, with an average value of ∼0.27 m 2 g −1 . Our determinations of absorption and scattering by atmospheric particles coupled with radiative transfer simulations suggest that aerosol deposition may have sizable effect on ocean optical properties, including remote sensing reflectance under certain scenarios of deposition events, residence time of deposited particles within the water column, and particle properties.