Abstract
An investigation was conducted of the poleward jet shift appearing in the Southern Hemisphere winter, by means of data simulated by a general circulation model. The poleward jet-shift in the model is found to be well simulated, although the jet in mid-winter exists fairly southward compared with observation. It is conjectured that the poleward jet-shift in the model was preconditioned by the wave breaking of a forerunning Rossby wave with zonal-wavenumber 1, and then it occurred by the breaking of another strong Rossby wave packet with zonal-wavenumber 1 at the jet axis in the upper stratosphere.
