Rossby Normal Modes in Nonuniform Background Configurations. Part II. Equinox and Solstice Conditions

Abstract

Abstract The existence of planetary normal modes in the presence of realistic mean fields is examined. For sufficiently large wavenumber m, or meridional index n, the response of the Rossby modes is diffused beyond identification. This is primarily a result of the Doppler shifting of mean winds and supersedes the increasing role of dissipation. Several initial modes for the first few wavenumbers should be both realizable and identifiable in typical conditions. “At least” the first three modes of wavenumber 1, the first two of wavenumber 2, and the first of wavenumber 3 should occur with periods isolated to within 12.5% of median values. The mode structures for the first four modes of wavenumbers 1, 2 and 3 are insensitive to the mean fields in the lowest two scale heights. In addition, the response of each of these is readily discernable in both equinox and solstice conditions. The modes' horizontal character is notably robust. Although the solutions typically exhibit regions where they are affected by th...