Skip to content

Research at St Andrews

Revisiting vacillations in shallow-water models of the stratosphere using potential-vorticity-based numerical algorithms

Research output: Contribution to journalArticle

DOI

Abstract

Polar vortex vacillations are investigated using long-term simulations of potential-vorticity (PV)-based shallow-water (SW) models for the stratosphere. In the models examined, mechanical forcing is applied through a time-independent topography mimicking tropospheric excitation of the stratosphere. Thermal forcing is applied through a linear relaxation of the mass field to a time-independent equilibrium state mimicking the radiative relaxation taking place in the stratosphere. The SW equations in the PV, velocity divergence, and acceleration divergence representation are solved for a range of resolutions using the "dia-batic contour-advective semi-Lagrangian" (DCASL) algorithm and a standard pure semi-Lagrangian (SL) algorithm. Using very different numerical algorithms enables the determination of the degree of numerical sensitivity and the properties of the vacillations with much greater accuracy than in previous related studies. The focus here is on the Lagrangian or material evolution of the polar vortex. The authors examine quasi-Lagrangian diagnostics based on equivalent latitude, the mass enclosed by PV contours, and the terms involved in its time evolution. The PV field forms the basis for calculating quasi-Lagrangian diagnostics. Variations in the mass enclosed by a PV contour are associated with nonconservative processes such as diabatic heating, friction, and irreversible small-scale mixing. Generally, the mass of the polar vortex increases under the action of diabatic mass fluxes, whereas it decreases under the action of dissipative mass fluxes. The results herein differ from previous results reported at T42 resolution by Rong and Waugh in which a spectral transform algorithm is used to solve the SW equations in a vorticity-divergence-mass representation, and in which dissipation is provided by explicitly damping vorticity using hyperdiffusion. Except for the first large-amplitude oscillation, there is little sign of a clear, systematic phase shift between the dissipative and diabatic mass fluxes across the edge of the polar vortex, as proposed by Rong and Waugh as the main mechanism responsible for the vacillations. Concomitant with the absence of a phase shift, the vacillations tend to decay and occur intermittently. Rather than a phase shift, inherent fluctuations in both the diabatic and mass fluxes across the edge of the polar vortex appear to be responsible for the vacillations.

Close

Details

Original languageEnglish
Pages (from-to)1007-1022
Number of pages16
JournalJournal of the Atmospheric Sciences
Volume68
Issue number5
DOIs
Publication statusPublished - 1 May 2011

    Research areas

  • Arctic, Potential vorticity, Shallow water equations, Stratosphere, Vortices

Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by author

  1. Comparison of the Moist Parcel-In-Cell (MPIC) model with large-eddy simulation for an idealized cloud

    Böing, S. J., Dritschel, D. G., Parker, D. J. & Blyth, A. M., 29 Apr 2019, In : Quarterly Journal of the Royal Meteorological Society. In press, 17 p.

    Research output: Contribution to journalArticle

  2. On the regularity of the Green-Naghdi equations for a rotating shallow fluid layer

    Dritschel, D. G. & Jalali, M. R., 25 Apr 2019, In : Journal of Fluid Mechanics. 865, p. 100-136

    Research output: Contribution to journalArticle

  3. Scale-invariant singularity of the surface quasigeostrophic patch

    Scott, R. K. & Dritschel, D. G., 25 Mar 2019, In : Journal of Fluid Mechanics. 863, 12 p., R2.

    Research output: Contribution to journalArticle

Related by journal

  1. Dynamics of ITCZ width: Ekman processes, non-Ekman processes, and links to sea surface temperature

    Byrne, M. P. & Thomas, R., Sep 2019, In : Journal of the Atmospheric Sciences. 76, 9, p. 2869-2884 16 p.

    Research output: Contribution to journalArticle

  2. The stability of Mars' annular polar vortex

    Seviour, W., Waugh, D. & Scott, R. K., May 2017, In : Journal of the Atmospheric Sciences. 74, 5, p. 1533-1547

    Research output: Contribution to journalArticle

  3. The Troposphere-to-Stratosphere Transition in Kinetic Energy Spectra and Nonlinear Spectral Fluxes as Seen in ECMWF Analyses

    Burgess, B. H., Erler, A. R. & Shepherd, T. G., Feb 2013, In : Journal of the Atmospheric Sciences. 70, 2, p. 669-687 19 p.

    Research output: Contribution to journalArticle

  4. A barotropic model of the angular momentum-conserving potential vorticity staircase in spherical geometry

    Dunkerton, T. J. & Scott, R. K., 2008, In : Journal of the Atmospheric Sciences. 65, 4, p. 1105-1136

    Research output: Contribution to journalArticle

Related by journal

  1. Journal of the Atmospheric Sciences (Journal)

    Richard Kirkness Scott (Editor)
    2006 → …

    Activity: Publication peer-review and editorial work typesEditor of research journal

  2. Journal of the Atmospheric Sciences (Journal)

    Riwal Plougonven (Editor)
    2005 → …

    Activity: Publication peer-review and editorial work typesEditor of research journal

  3. Journal of the Atmospheric Sciences (Journal)

    David Gerard Dritschel (Editor)
    2005 → …

    Activity: Publication peer-review and editorial work typesEditor of research journal

  4. Journal of the Atmospheric Sciences (Journal)

    Ali Reza Mohebalhojeh (Editor)
    2005 → …

    Activity: Publication peer-review and editorial work typesEditor of research journal

ID: 263184976

Top