Further observational evidence of normal mode Rossby waves with higher meridional mode numbers is presented with the aid of global data from the troposphere to the stratosphere over the period November 1979 through April 1986. It is shown, without using an a priori assumption of meridional structure, that the third antisymmetric modes of zonal wavenumbers 1 and 2, i.e., (1,4) and (2,4) modes, substantially exist in the real atmosphere. These modes are, however, easily influenced by the nonuniform background field even in the equinoctial season; amplitude submaxima near the equator are apt to be dubious in the upper stratosphere so that the prototype meridional structure becomes obscure. The period of the (1,4) mode often falls into that of the (1,3) mode, about 16 days. Hence, these two modes cannot be classified simply by their periods, but the separation is made by their meridional structure. An appearance calendar of various modes is also presented for the analysis period. It is found that each mode appears irregularly throughout the year and that the year-to-year variation is fairly large.
All Science Journal Classification (ASJC) codes
- Geochemistry and Petrology