Spatio-temporal stability analysis applied to monsoon anticyclone flow
Quarterly Journal of the Royal Meteorological Society
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Rupp, P., & Haynes, P. (2020). Spatio-temporal stability analysis applied to monsoon anticyclone flow. Quarterly Journal of the Royal Meteorological Society, 146 (729), 1861-1879. https://doi.org/10.1002/qj.3771
© 2020 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society. Flow on a beta-plane driven by a steady localised anticyclonic forcing of potential vorticity (or equivalently a mass source) is considered as a simple model of the Asian monsoon flow in the upper troposphere. Previous authors have noted that the response may be steady, or unsteady, according to the magnitude of the forcing, with the unsteadiness manifested as westward eddy shedding. A detailed study of the transition between steady and eddy-shedding regimes reveals a third regime ('break up'), for intermediate forcing magnitude, where the flow is steady in the neighbourhood of the forcing, but the westward extending plume of low potential vorticity breaks up into isolated anticyclonic vortices some distance away from the forcing region. A related spatio-temporal instability problem for flow on a beta plane is specified and analysed. The flow can be stable, convectively unstable or absolutely unstable. It is argued that these three stability regimes correspond to the steady, break-up and eddy-shedding regimes for the forced flow and good quantitative correspondence between the regimes is demonstrated by explicit solution of the spatio-temporal stability problem.
We acknowledge support from the European Commission project StratoClim, 7th Framework Programme, project no. 603557, and the European Research Council, ACCI project no. 267760.
European Research Council (267760)
EC FP7 CP (603557)
External DOI: https://doi.org/10.1002/qj.3771
This record's URL: https://www.repository.cam.ac.uk/handle/1810/303218
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