Large Contribution of Coarse Mode to Aerosol Microphysical and Optical Properties: Evidence from Ground-based Observations of a Trans-Pacific Dust Outbreak at a High-Elevation North American Site

Title Large Contribution of Coarse Mode to Aerosol Microphysical and Optical Properties: Evidence from Ground-based Observations of a Trans-Pacific Dust Outbreak at a High-Elevation North American Site
Publication TypeJournal Article
Year of Publication2017
JournalJournal of the Atmospheric Sciences
Date Published02/2017
Abstract

Our work is motivated by previous studies of trans-Atlantic transport of Saharan dust and observed quasi-static nature of coarse mode aerosol with a volume median diameter (VMD) of approximately 3.5 μm. We examine coarse mode contributions from trans-Pacific transport of dust to North American aerosol properties using a data set collected at the high-elevation Storm Peak Laboratory (SPL) and the nearby Atmospheric Radiation Measurement (ARM) Mobile Facility. Collected ground-based data are complemented by quasi-global model simulations and satellite and ground-based observations. We identify a major dust event associated mostly with a trans-Pacific plume (about 65% of near-surface aerosol mass) where the coarse mode with moderate (~3 μm) VMD is distinct and contributes substantially to total aerosol volume (up to 70%) and scattering (up to 40%). Our results demonstrate that the identified plume at the SPL site has a considerable fraction of super-micron particles (VMD~3 μm), and thus suggest that these particles have a fairly invariant behavior despite trans-Pacific transport. If confirmed in additional studies, this invariant behavior may simplify considerably parameterizations for size-dependent processes associated with dust transport and removal.

URLhttp://journals.ametsoc.org/doi/abs/10.1175/JAS-D-16-0256.1
DOI10.1175/JAS-D-16-0256.1
Journal: Journal of the Atmospheric Sciences

Our work is motivated by previous studies of trans-Atlantic transport of Saharan dust and observed quasi-static nature of coarse mode aerosol with a volume median diameter (VMD) of approximately 3.5 μm. We examine coarse mode contributions from trans-Pacific transport of dust to North American aerosol properties using a data set collected at the high-elevation Storm Peak Laboratory (SPL) and the nearby Atmospheric Radiation Measurement (ARM) Mobile Facility. Collected ground-based data are complemented by quasi-global model simulations and satellite and ground-based observations. We identify a major dust event associated mostly with a trans-Pacific plume (about 65% of near-surface aerosol mass) where the coarse mode with moderate (~3 μm) VMD is distinct and contributes substantially to total aerosol volume (up to 70%) and scattering (up to 40%). Our results demonstrate that the identified plume at the SPL site has a considerable fraction of super-micron particles (VMD~3 μm), and thus suggest that these particles have a fairly invariant behavior despite trans-Pacific transport. If confirmed in additional studies, this invariant behavior may simplify considerably parameterizations for size-dependent processes associated with dust transport and removal.

DOI: 10.1175/JAS-D-16-0256.1
Year of Publication: 2017
Citation: " Large Contribution of Coarse Mode to Aerosol Microphysical and Optical Properties: Evidence from Ground-based Observations of a Trans-Pacific Dust Outbreak at a High-Elevation North American Site." Journal of the Atmospheric Sciences. 2017.