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Convective and boundary layer parametrizations in a diagnostic model of atmospheric fronts
Author(s) -
Thorpe A. J.,
Nash C. A.
Publication year - 1984
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 - 10.1002/qj.49711046409
Subject(s) - parametrization (atmospheric modeling) , forcing (mathematics) , front (military) , convection , amplitude , mechanics , boundary layer , convective boundary layer , cold front , physics , boundary value problem , circulation (fluid dynamics) , planetary boundary layer , meteorology , geology , mathematics , atmospheric sciences , mathematical analysis , optics , radiative transfer
Numerical integrations of initial value problems and observations have shown that along‐front geostrophy is a good approximation in frontal regions, even in the presence of strong frontogenetic forcing. Consequently the cross‐frontal circulation equation described by A. Eliassen in 1961 is a powerful diagnostic tool. Extra terms have been added to represent parametrized convective and boundary layer physics. The inclusion of cumulus heating modelled on that used in CISK theories produces bands of ascent whose scale decreases as the heating amplitude increases. For realistic cold fronts bands are produced just ahead of and behind the surface temperature contrast depending on the type of frontogenetic forcing. The application of this convective parametrization to finite amplitude circulations about a front is rather different from previous uses in theories of CISK. The solution method makes it simple to examine a much larger class of representations, hence providing a fresh appraisal of the parametrizations. The integrated frontogenetic tendency is calculated in the frame of reference moving with the front for the various cases considered. This allows discussion of the notion of a steady state front and indicates the crucial role of convective and boundary layer processes.