The influence of stratospheric potential vorticity on baroclinic instability

L. A. Smy, R. K. Scott

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

This article examines the dynamical coupling between the stratosphere and troposphere by considering the effect of direct perturbations to stratospheric potential vorticity on the evolution of midlatitude baroclinic instability, in a simple extension of an Eady model. A Simulation in which stratospheric potential vorticity is exactly Zero is used as a control case, and both zonally symmetric and asymmetric perturbations to the stratospheric potential vorticity are then considered, the former representative of a strong polar vortex, the latter representative of the stratospheric state following a major sudden warming. Both types of stratospheric perturbation result in significant changes to the synoptic-scale evolution of Surface temperature, as well its to zonally and globally averaged tropospheric quantities. In the case of a zonally symmetric perturbation, the linear growth rate of all unstable modes decreases with increasing perturbation amplitude. Initial growth rates in cases with significant asymmetric perturbation,, are also weaker than those of the control case, but filial eddy kinetic energy values are much larger due to the growth of low zonal wavenumbers triggered by the initial stratospheric perturbation. A comparison of the zonally symmetric and asymmetric perturbations gives some insight into the possible influence of pre- or post-sudden-warming conditions on tropospheric evolution. Copyright (C) 2009 Royal Meteorological Society

Original languageEnglish
Pages (from-to)1673-1683
Number of pages11
JournalQuarterly Journal of the Royal Meteorological Society
Volume135
Issue number644
DOIs
Publication statusPublished - Oct 2009

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