Tropopause-Level Waveguides

Abstract

Jet streams located on the dynamical tropopause are accompanied by coaligned bands of enhanced potential vorticity (PV) gradients, and these bands can serve as space?time evolving waveguides for synoptic and larger-scale flow. Consideration is given to the detection and examination of the along-flow extent and lateral confinement of the waveguides on the dynamic tropopause (i.e., iso-PV surface) and on tropopause-cutting isentropic surfaces. Thereafter a two-part study is undertaken of the possible interaction between such waveguides (i.e., jet streams). First, a highly idealized theoretical model points to the nature of the dynamical linkage that can exist between perturbations on coaligned waveguides. Second, diagnostic analysis of two observed events helps identify the contemporaneous space?time evolution of the jets and serves to illustrate the nature of the transfer of wave activity from the extratropical waveguide onto a subtropical and a polar waveguide, respectively.