A numerical study of the genesis of extratropical convective mesovortices. Part I: evolution and dynamics

S. S. Chen, W. M. Frank

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A hypothesis is proposed that mesovortices form in the stratiform rain regions of mesoscale convective systems (MCSs) due to the reduction of static stability that reduces the effective local Rossby radius in such regions. A mesoscale model is used to simulate mesovortex genesis in analytically generated pre-MCS large-scale environments. The model simultaneously incorporates parameterized convection and a grid-resolvable convective scheme containing the effects of hydrostatic water loading, condensation (evaporation), freezing (melting), and sublimation. A control simulation is performed with a specified pre-MCS environment that is characterized by a midtropospheric short wave, a low-level jet ahead of the short-wave trough, a large area of conditionally unstable air, a deep layer of moisture, and small vertical wind shear. A mesovortex forms within a stratiform region behind a leading convective line. The evolution and structure of the mesovortex are similar to observations of the mesovortices associated with MCSs over land at midlatidues. -from Authors

Original languageEnglish (US)
Pages (from-to)2401-2426
Number of pages26
JournalJournal of the Atmospheric Sciences
Issue number15
StatePublished - Jan 1 1993


ASJC Scopus subject areas

  • Atmospheric Science

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