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| Titel |
Theoretical basis for convective invigoration due to increased aerosol concentration |
| VerfasserIn |
Z. J. Lebo, J. H. Seinfeld |
| 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 ; 11, no. 11 ; Nr. 11, no. 11 (2011-06-09), S.5407-5429 |
| Datensatznummer |
250009810
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| Publikation (Nr.) |
 copernicus.org/acp-11-5407-2011.pdf |
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| Zusammenfassung |
The potential effects of increased aerosol loading on the
development of deep convective clouds and resulting
precipitation amounts are studied by employing the Weather
Research and Forecasting (WRF) model as a detailed
high-resolution cloud resolving model (CRM) with both detailed
bulk and bin microphysics schemes. Both models include a
physically-based activation scheme that incorporates a
size-resolved aerosol population. We demonstrate that
the aerosol-induced effect is controlled by the balance
between latent heating and the increase in condensed water
aloft, each having opposing effects on buoyancy. It is also
shown that under polluted conditions, increases in the CCN number concentration reduce
the cumulative precipitation due to the competition between
the sedimentation and evaporation/sublimation timescales. The
effect of an increase in the IN number concentration on the
dynamics of deep convective clouds is small and the
resulting decrease in domain-averaged cumulative
precipitation is shown not to be statistically significant, but may act to
suppress precipitation. It is also shown that even
in the presence of a decrease in the domain-averaged
cumulative precipitation, an increase in the precipitation
variance, or in other words, andincrease in rainfall intensity,
may be expected in more polluted environments, especially in moist environments.
A significant difference exists between the predictions based on the bin and bulk
microphysics schemes of precipitation and the influence of
aerosol perturbations on updraft velocity within the
convective core. The bulk microphysics scheme shows little
change in the latent heating rates due to an increase in the CCN number concentration, while the
bin microphysics scheme demonstrates significant increases in
the latent heating aloft with increasing CCN number
concentration. This suggests that even a detailed two-bulk
microphysics scheme, coupled to a detailed activation scheme, may not be sufficient to predict small
changes that result from perturbations in aerosol loading. |
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