Interaction of North Atlantic baroclinic wave packets and the Mediterranean storm track

Observational studies show that the main energy source for developing cyclones is due to downstream radiation from existing upstream disturbances. This process is involved in the propagation of coherent wave packets linking the North Atlantic and Mediterranean storm tracks in winter. To understand the link, the Rossby wave packets have been analyzed for the winter season 2004/05 by means of wave envelope, energetic, and wave-activity diagnostics. Two specifically selected cases are presented: one with clear propagation of the wave packet to the Mediterranean region from the North Atlantic storm track, and the other with zonal propagation of the wave packets along the central latitude of the North Atlantic storm track. The dynamical effects leading to the distinct propagation characteristics of the two cases are discussed. It is shown that the two cases make clear impacts on the horizontal flux of wave activity across a domain surrounding the Mediterranean storm track.