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On a theory of the evolution of surface cold frontsThe governing vorticity and divergence equations in the surface layer are derived and the roles of the different terms and feedback mechanisms are investigated in semigeostrophic and nongeostrophic cold-frontal systems. A planetary boundary layer model is used to perform sensitivity tests to determine that in a cold front the ageostrophic feedback mechanism as defined by Orlanski and Ross tends to act as a positive feedback mechanism, enhancing vorticity and convergence growth. Therefore, it cannot explain the phase shift between convergence and vorticity as simulated by Orlanski and Ross. An alternative plausible, though tentative, explanation in terms of a gravity wave is offered. It is shown that when the geostrophic deformation increases, nonlinear terms in the divergence equation may become important and further destabilize the system.
Document ID
19880036524
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Levy, Gad
(Washington Univ. Seattle, WA, United States)
Bretherton, Christopher S.
(Washington, University Seattle, United States)
Date Acquired
August 13, 2013
Publication Date
November 15, 1987
Publication Information
Publication: Journal of the Atmospheric Sciences
Volume: 44
ISSN: 0022-4928
Subject Category
Meteorology And Climatology
Accession Number
88A23751
Funding Number(s)
CONTRACT_GRANT: NAGW-679
Distribution Limits
Public
Copyright
Other

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