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| Titel |
Variation in aerosol nucleation and growth in coal-fired power plant plumes due to background aerosol, meteorology and emissions: sensitivity analysis and parameterization. |
| VerfasserIn |
R. G. Stevens, C. L. Lonsdale, C. A. Brock, M. K. Reed, J. H. Crawford, J. S. Holloway, T. B. Ryerson, L. G. Huey, J. B. Nowak, J. R. Pierce |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063201
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| Zusammenfassung |
| New-particle formation in the plumes of coal-fired power plants and other anthropogenic
sulphur sources may be an important source of particles in the atmosphere. It remains
unclear, however, how best to reproduce this formation in global and regional aerosol models
with grid-box lengths that are 10s of kilometres and larger. The predictive power of these
models is thus limited by the resultant uncertainties in aerosol size distributions. In this
presentation, we focus on sub-grid sulphate aerosol processes within coal-fired power plant
plumes: the sub-grid oxidation of SO2 with condensation of H2SO4 onto newly-formed and
pre-existing particles.
Based on the results of the System for Atmospheric Modelling (SAM), a Large-Eddy
Simulation/Cloud-Resolving Model (LES/CRM) with online TwO Moment Aerosol
Sectional (TOMAS) microphysics, we develop a computationally efficient, but physically
based, parameterization that predicts the characteristics of aerosol formed within coal-fired
power plant plumes based on parameters commonly available in global and regional-scale
models. Given large-scale mean meteorological parameters, emissions from the power plant,
mean background condensation sink, and the desired distance from the source, the
parameterization will predict the fraction of the emitted SO2 that is oxidized to H2SO4, the
fraction of that H2SO4 that forms new particles instead of condensing onto preexisting
particles, the median diameter of the newly-formed particles, and the number of
newly-formed particles per kilogram SO2 emitted.
We perform a sensitivity analysis of these characteristics of the aerosol size distribution to
the meteorological parameters, the condensation sink, and the emissions. In general,
new-particle formation and growth is greatly reduced during polluted conditions due to the
large preexisting aerosol surface area for H2SO4 condensation and particle coagulation. The
new-particle formation and growth rates are also a strong function of the amount of sunlight
and NOx since both control OH concentrations. Decreases in NOx emissions without
simultaneous decreases in SO2 emissions increase new-particle formation and growth due to
increased oxidation of SO2.
The parameterization we describe here should allow for more accurate predictions of
aerosol size distributions and a greater confidence in the effects of aerosols in climate and
health studies. |
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