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| Titel |
Comprehensive mapping and characteristic regimes of aerosol effects on the formation and evolution of pyro-convective clouds |
| VerfasserIn |
D. Chang, Y. Cheng, P. Reutter, J. Trentmann, S. M. Burrows, P. Spichtinger, S. Nordmann, M. O. Andreae, U. Pöschl, H. Su |
| 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 ; 15, no. 18 ; Nr. 15, no. 18 (2015-09-21), S.10325-10348 |
| Datensatznummer |
250120039
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| Publikation (Nr.) |
 copernicus.org/acp-15-10325-2015.pdf |
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| Zusammenfassung |
| A recent parcel model study (Reutter et al., 2009) showed three
deterministic regimes of initial cloud droplet formation, characterized by
different ratios of aerosol concentrations (NCN) to updraft velocities.
This analysis, however, did not reveal how these regimes evolve during the
subsequent cloud development. To address this issue, we employed the Active
Tracer High Resolution Atmospheric Model (ATHAM) with full microphysics and
extended the model simulation from the cloud base to the entire column of a
single pyro-convective mixed-phase cloud. A series of 2-D simulations (over
1000) were performed over a wide range of NCN and dynamic conditions.
The integrated concentration of hydrometeors over the full spatial and
temporal scales was used to evaluate the aerosol and dynamic effects. The
results show the following. (1) The three regimes for cloud condensation nuclei (CCN)
activation in the parcel model (namely aerosol-limited, updraft-limited, and
transitional regimes) still exist within our simulations, but net production
of raindrops and frozen particles occurs mostly within the updraft-limited
regime. (2) Generally, elevated aerosols enhance the formation of cloud
droplets and frozen particles. The response of raindrops and precipitation
to aerosols is more complex and can be either positive or negative as a
function of aerosol concentrations. The most negative effect was found for
values of NCN of ~ 1000 to 3000 cm−3. (3) The
nonlinear properties of aerosol–cloud interactions challenge the conclusions
drawn from limited case studies in terms of their representativeness, and
ensemble studies over a wide range of aerosol concentrations and other
influencing factors are strongly recommended for a more robust assessment of
the aerosol effects. |
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