Linear normal modes of a moving, shallow-water barotropic vortex Article

Willoughby, HE. (1990). Linear normal modes of a moving, shallow-water barotropic vortex . JOURNAL OF THE ATMOSPHERIC SCIENCES, 47(17), 2141-2148. 10.1175/1520-0469(1990)047<2141:LNMOAM>2.0.CO;2

cited authors

  • Willoughby, HE

authors

abstract

  • In this model, meridional motion of vortices with LR≠0 (total relative angular momentum) always acts to adjust LR toward zero through conservation of absolute angular momentum. Since the asymmetric perturbations are Rossby waves that propagate upon the radial gradient of mean relative vorticity, the mode at zero frequency experiences critical-radius absorption where the mean swirling wind is zero - at the boundary between cyclonic and anticyclonic mean circulation and at the edge of the vortex. Regardless of the sign of LR, the wave momentum convergence is concentrated at these critical radii and weakens the circulation while expanding it spatially. When LR=0, waves emanating from the cyclonic and anticyclonic circulations interfere destructively, so that the vortex radiates no angular momentum to its environment. -from Author

publication date

  • January 1, 1990

published in

start page

  • 2141

end page

  • 2148

volume

  • 47

issue

  • 17