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| Titel |
On the application of the classic Kessler and Berry schemes in Large Eddy Simulation models with a particular emphasis on cloud autoconversion, the onset time of precipitation and droplet evaporation |
| VerfasserIn |
S. Ghosh, P. R. Jonas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 16, no. 5 ; Nr. 16, no. 5, S.628-637 |
| Datensatznummer |
250013283
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| Publikation (Nr.) |
 copernicus.org/angeo-16-628-1998.pdf |
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| Zusammenfassung |
Many Large Eddy Simulation (LES) models use
the classic Kessler parameterisation either as it is or in a modified form to
model the process of cloud water autoconversion into precipitation. The Kessler
scheme, being linear, is particularly useful and is computationally
straightforward to implement. However, a major limitation with this scheme lies
in its inability to predict different autoconversion rates for maritime and
continental clouds. In contrast, the Berry formulation overcomes this
difficulty, although it is cubic. Due to their different forms, it is difficult
to match the two solutions to each other. In this paper we single out the
processes of cloud conversion and accretion operating in a deep model cloud and
neglect the advection terms for simplicity. This facilitates exact analytical
integration and we are able to derive new expressions for the time of onset of
precipitation using both the Kessler and Berry formulations. We then discuss the
conditions when the two schemes are equivalent. Finally, we also critically
examine the process of droplet evaporation within the framework of the classic
Kessler scheme. We improve the existing parameterisation with an accurate
estimation of the diffusional mass transport of water vapour. We then
demonstrate the overall robustness of our calculations by comparing our results
with the experimental observations of Beard and Pruppacher, and find excellent
agreement.
Key words. Atmospheric composition and structure ·
Cloud physics and chemistry · Pollution · Meteorology and atmospheric dynamics
· Precipitation |
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