Eddy-forced coherent structures as a prototype of atmospheric blocking
1987; Wiley; Volume: 113; Issue: 476 Linguagem: Inglês
10.1256/smsqj.47612
ISSN1477-870X
Autores Tópico(s)Tropical and Extratropical Cyclones Research
ResumoQuarterly Journal of the Royal Meteorological SocietyVolume 113, Issue 476 p. 681-704 Article Eddy-Forced Coherent Structures As A Prototype of Atmospheric Blocking Keith Haines, Keith Haines Space and Atmospheric Physics Group, Department of Physics, Imperial College, LondonSearch for more papers by this authorJohn Marshall, John Marshall Space and Atmospheric Physics Group, Department of Physics, Imperial College, LondonSearch for more papers by this author Keith Haines, Keith Haines Space and Atmospheric Physics Group, Department of Physics, Imperial College, LondonSearch for more papers by this authorJohn Marshall, John Marshall Space and Atmospheric Physics Group, Department of Physics, Imperial College, LondonSearch for more papers by this author First published: April 1987 https://doi.org/10.1002/qj.49711347613Citations: 80AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract The relevance of nonlinear free solutions of the equivalent barotropic vorticity equation known as 'modons' or 'vortex pairs' is reconsidered as a prototype of atmospheric blocking. It is argued that modons are highly appropriate reference solutions from which to consider the dynamics of blocks accounting for their local nature, their stability and longevity. Nonlinear resonance studies with an equivalent barotropic numerical model on a β-plane channel demonstrate the ease and vigour with which vortex pairs can be excited by a vorticity-forcing function of the appropriate form. Localized nonlinear structures which can be identified with modons exist on blocking timescales even in parameter ranges which allow stationary Rossby waves. Thecircumstances in which synoptic systems can provide an appropriate forcing function are investigated by studying the interaction between a modon and a train of travelling vortices. It is shownthat the anomalous transfer of potential vorticity induced by the straining of synoptic systems propagating in a diffluent jet is in a sense to maintain the modon against dissipation. Time sequences of the potential vorticity field from the equivalent barotropic model bear a remarkable resemblance to isentropic potential vorticity maps observed during a blocking episode and suggestthat much of the detail can be understood in terms of the passive deformation of baroclinically inactive weather systems. References Arakawa, A. 1966 Computational design for long-term numerical integration of the equations of fluid motion: Two-dimensional incompressible flow: Part 1. J. Comput. Phys., 1, 119–143 10.1016/0021-9991(66)90015-5 CASGoogle Scholar Baines, P. 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