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| Titel |
The Role of Initial Cloud Condensation Nuclei Concentration in Hail Using the WRF NSSL 2-moment Microphysics Scheme |
| VerfasserIn |
Xiaofei Li, Qinghong Zhang, Huiwen Xue |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140910
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| Publikation (Nr.) |
 EGU/EGU2017-4362.pdf |
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| Zusammenfassung |
| The effects of the initial cloud condensation nuclei (CCN) concentrations (100–3000 mg−1)
on hail properties were investigated in an idealized hail storm experiment using the Weather
Research and Forecasting (WRF) model, with the National Severe Storms Laboratory
two-moment microphysics scheme. The initial CCN concentration had obvious
non-monotonic effects on the mixing ratio, number concentrations, and radius of hail, both in
clouds and at the surface, with a threshold CCN concentration between 300 and 500 mg−1.
An increasing CCN concentration is conducive (suppressive) to the amount of surface hail
precipitation below (above) the threshold. The non-monotonic effects were due to both the
thermodynamics and microphysics. Below the threshold, the mixing ratios of cloud droplets
and ice crystals increased dramatically with the increasing CCN concentration, resulting in
more latent heat being released from vapor condensation and intensified updraft volume. The
extent of the riming process, which is the primary process for hail production, increased
dramatically. Above the threshold, the mixing ratio of cloud droplets and ice crystals
increased continuously, but the maximum updraft volume was weakened because of
reduced latent heating, which was related to the reduced riming rate in the storm core
area. The smaller ice crystals reduced the formation of hail and smaller clouds,
with decreased rain water reducing riming efficiency so that graupel and hail also
decreased with increasing CCN concentration, which is unfavorable for hail growth. |
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