Observation of ambient aerosol particle growth due to in-cloud processes within boundary layers
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Authors
Wang, Jian
Daum, Peter H.
Kleinman, Lawrence I.
Lee, Yin-Nan
Schwartz, Stephen E.
Springston, Stephen R.
Jonsson, Haflidi
Covert, David
Elleman, Robert
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Date of Issue
2007
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American Geophysical Union (AGU)
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Abstract
Aerosol microphysical and optical properties were measured on board the CIRPAS Twin Otter aircraft during 16 flights at the Southern Great Plain (SGP) site in northern central Oklahoma as part of the Aerosol Intensive Operation period in May 2003. Within well-mixed boundary layers on four cloudy days, vertical profiles measured on board the Twin Otter show that dry aerosol size, volume concentration, and scattering coefficients all increased with increasing altitude, whereas the total number concentration remained essentially constant. A one-dimensional model, which uses simultaneous meteorological measurements as inputs, shows that the observed increase in aerosol volume concentration with increasing altitude is consistent with in-cloud sulfate production at the top of the boundary layer. The sulfate production rate was sufficiently fast to overcome the homogenization resulting from turbulent mixing. In contrast, on cloud-free days, measurements on a second aircraft show nearly uniform aerosol volume concentrations within well-mixed boundary layers. The observed vertical gradients in aerosol volume concentration suggest that even within well-mixed boundary layers, surface measurements may not be representative of aerosols properties (e.g., loading and scattering coefficients, etc.) at elevated altitudes, especially when SO2 concentration and cloud coverage are high.
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Article
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The article of record as published may be located at http://dx.doi.org/10.1029/2006JD007989.
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Citation
Journal of Geophysical Research, Vol. 112, D14207
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.