A Unified Three-Dimensional Instability Theory of the Onset of Blocking and Cyclogenesis. II. Teleconnection Patterns

Abstract The instability characteristics of three-dimensional Northern Hemisphere average winter tropospheric flow are examined in a two-layer spherical quasi-geostrophic model. All the growing modes from the fastest down to the first stationary but growing mode have been examined for three cases (1, 2a and 3) having increasingly larger static stability parameters. Comparisons with observations and with the results of the corresponding barotropic model are presented. It is found that the modes for cases 1, 2a and 3 can be divided into six approximately distinct classes. Class A modes are rapidly propagating monopole cyclogenesis disturbances with largest amplitudes in the geographical locations of the storm tracks in the Pacific and Atlantic Oceans. Class B and C modes are respectively Pacific and Pacific and Atlantic onset-of-blocking dipole modes with longer periods than class A modes and which like class A disturbances, have westward tilts with height. They also have largest amplitudes upstream of the ...