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| Titel |
Uncertainty assessment of current size-resolved parameterizations for below-cloud particle scavenging by rain |
| VerfasserIn |
X. Wang, L. Zhang, M. D. Moran |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 12 ; Nr. 10, no. 12 (2010-06-29), S.5685-5705 |
| Datensatznummer |
250008577
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| Publikation (Nr.) |
 copernicus.org/acp-10-5685-2010.pdf |
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| Zusammenfassung |
| Current theoretical and empirical size-resolved parameterizations of the
scavenging coefficient (Λ), a parameter commonly used in aerosol
transport models to describe below-cloud particle scavenging by rain, have
been reviewed in detail and compared with available field and laboratory
measurements. Use of different formulations for raindrop-particle collection
efficiency can cause uncertainties in size-resolved Λ values of one
to two orders of magnitude for particles in the 0.01–3 μm diameter
range. Use of different formulations of raindrop number size distribution
can cause Λ values to vary by a factor of 3 to 5 for all particle
sizes. The uncertainty in Λ caused by the use of different droplet
terminal velocity formulations is generally small than a factor of 2. The
combined uncertainty due to the use of different formulations of
raindrop-particle collection efficiency, raindrop size spectrum, and
raindrop terminal velocity in the current theoretical framework is not
sufficient to explain the one to two order of magnitude under-prediction of
Λ for the theoretical calculations relative to the majority of
field measurements. These large discrepancies are likely caused by
additional known physical processes (i.e, turbulent transport and mixing,
cloud and aerosol microphysics) that influence field data but that are not
considered in current theoretical Λ parameterizations. The
predicted size-resolved particle concentrations using different theoretical
Λ parameterization can differ by up to a factor of 2 for particles
smaller than 0.01 μm and by a factor of >10 for particles larger than
3 μm after 2–5 mm of rain. The predicted bulk mass and number
concentrations (integrated over the particle size distribution) can differ
by a factor of 2 between theoretical and empirical Λ
parameterizations after 2–5 mm of moderate intensity rainfall. |
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