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Numerical modelling of mixed‐phase frontal clouds observed during the CWVC project
Author(s) -
Clark P. D.,
Choularton T. W.,
Brown P. R. A.,
Field P. R.,
Illingworth A. J.,
Hogan R. J.
Publication year - 2005
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1256/qj.03.210
Subject(s) - ice nucleus , latent heat , precipitation , meteorology , atmospheric sciences , environmental science , cloud physics , cloud computing , ice crystals , nucleation , climatology , liquid water content , geology , geography , physics , computer science , thermodynamics , operating system
The Met Office's cloud‐resolving model was used to model mixed‐phase frontal clouds observed as part of the Clouds, Water Vapour and Climate programme between 1999 and 2001. The clouds were studied using the Met Office's C130 aircraft and the Chilbolton radar facility. In the model, precipitation forms in updraughts then falls, giving rise to regions of high radar reflectivity similar to those observed. The vertical motions were driven by conditional instability or shear instability. The sensitivity of the model results to the microphysics was examined by varying the number of primary ice nuclei and switching off the Hallett–Mossop process. It is demonstrated that the ice nucleation processes, both primary nucleation and secondary ice particle production, are key to the precipitation production in the cloud. This occurs both through the detail of cloud microphysics and the release of latent heat of fusion in the cloud. This is very sensitive to the details of the microphysics and can markedly change the cloud dynamics. In both cases it seems that the cloud dynamics can be simulated locally without considering the large‐scale forcing. © Royal Meteorological Society, 2005. The contributions of P. R. A. Brown and P. R. Field are Crown copyright.