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| Titel |
Effect of hygroscopic seeding on warm rain clouds – numerical study using a hybrid cloud microphysical model |
| VerfasserIn |
N. Kuba, M. Murakami |
| 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. 7 ; Nr. 10, no. 7 (2010-04-09), S.3335-3351 |
| Datensatznummer |
250008334
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| Publikation (Nr.) |
 copernicus.org/acp-10-3335-2010.pdf |
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| Zusammenfassung |
| The effect of hygroscopic seeding on warm rain clouds was examined using a
hybrid cloud microphysical model combining a Lagrangian Cloud Condensation
Nuclei (CCN) activation model, a semi-Lagrangian droplet growth model, and
an Eulerian spatial model for advection and sedimentation of droplets. This
hybrid cloud microphysical model accurately estimated the effects of CCN on
cloud microstructure and suggested the following conclusions for a moderate
continental air mass (an air mass with a large number of background CCN).
(1) Seeding can hasten the onset of surface rainfall and increase the
accumulated amount of surface rainfall if the amount and radius of seeding
particles are appropriate. (2) The optimal radius of monodisperse particles
to increase rainfall becomes larger with the increase in the total mass of
seeding particles. (3) Seeding with salt micro-powder can hasten the onset
of surface rainfall and increase the accumulated amount of surface rainfall
if the amount of seeding particles is sufficient. (4) Seeding by a
hygroscopic flare decreases rainfall in the case of large updraft velocity
(shallow convective cloud) and increases rainfall slightly in the case of
small updraft velocity (stratiform cloud). (5) Seeding with hygroscopic
flares including ultra-giant particles (r>5 μm) hastens the onset
of surface rainfall but may not significantly increase the accumulated
surface rainfall amount. (6) Hygroscopic seeding increases surface rainfall
by two kinds of effects: the "competition effect" by which large soluble
particles prevent the activation of smaller particles and the "raindrop
embryo effect" in which giant soluble particles can immediately become
raindrop embryos. In some cases, one of the effects works, and in other
cases, both effects work, depending on the updraft velocity and the amount
and size of seeding particles. |
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