Lie symmetries and exact solutions of the barotropic vorticity equation

TL;DR

This paper employs Lie group methods to analyze symmetries and derive exact solutions of the barotropic vorticity equation on various geophysical models, including the sphere and beta-plane, extending previous results.

Contribution

It systematically classifies Lie symmetries and constructs a broad family of exact solutions, including Rossby and Rossby--Haurwitz waves, for the vorticity equations.

Findings

Classified Lie symmetries for vorticity equations on different models

Derived invariant solutions including Rossby waves

Extended the family of solutions via partial invariance analysis

Abstract

Lie group methods are used for the study of various issues related to symmetries and exact solutions of the barotropic vorticity equation. The Lie symmetries of the barotropic vorticity equations on the $f$- and $\beta$-planes, as well as on the sphere in rotating and rest reference frames, are determined. A symmetry background for reducing the rotating reference frame to the rest frame is presented. The one- and two-dimensional inequivalent subalgebras of the Lie invariance algebras of both equations are exhaustively classified and then used to compute invariant solutions of the vorticity equations. This provides large classes of exact solutions, which include both Rossby and Rossby--Haurwitz waves as special cases. We also discuss the possibility of partial invariance for the $\beta$-plane equation, thereby further extending the family of its exact solutions. This is done in a more systematic and complete way than previously available in literature.