| For the first time, a generalized, self-consistent, weakly nonlinear theory is formulated that describes the dynamics of isolated anomalies embedded in a zonally varying background flow that is forced by topography and external potential vorticity (PV) forcing. The theory describes the dynamics of isolated anomalies having the form of coherent structures (CSs) and oscillatory Rossby wave packets (ORWPs); emphasis is placed on the CSs.; The primary goal of this study is to provide the theoretical framework for understanding how the combination of several physical processes affects the life cycles of CSs in the atmosphere. These processes, which have been shown in observational studies to play an important role in the dynamics of CSs, can be grouped into three broad categories: (1) modulation of the CS by the zonally uniform portion of the background flow; (2) modulation of the CS by the stationary wave portion of the background flow; and (3) modulation of the CS by a wave activity source, which contains contributions from the zonally varying background flow, topography, and external PV forcing. A unique aspect of this work is that these processes, which are contained in our analytically derived CS amplitude equation, are directly connected to a budget equation that is similar to those used in observational studies of atmospheric low frequency variability.; The zonally varying background flow, topography, and external PV forcing, which enter implicitly and explicitly into the amplitude evolution equation, combine to have a profound influence on the dynamics of CSs. The background flow and forcings produce local growth in the CSs, where the local growth is controlled by the horizontal spatial structure, magnitude and relative position of the topography and external PV forcing. The local growth results in (1) the emission of other CSs and/or ORWPs, (2) changes in the propagation speed of the CSs, and (3) the complete or partial trapping of the CSs. |
