Normal Mode Rossby Waves Observed in the Upper Stratosphere. Part II: Second Antisymmetric and Symmetric Modes of Zonal Wavenumbers 1 and 2

Abstract

Abstract A global analysis is made of large-scale traveling planetary waves in the upper stratosphere by the use of stratospheric height and thickness data up to the 1 mb level derived from the Stratospheric Sounding Unit (SSU) on TIROS-N and NOAA-A satellites for the period December 1979 through November 1981. The results of space-time power and cross-spectral analyses show the global existence of a westward traveling wave of zonal wavenumber 1 with a period of about 5 days and a westward traveling wave of zonal wavenumber 2 with a period of about 4 days. The structure and behavior of these waves are investigated by using the components of these period bands separated by a numerical band-pass filter. The 5-day wave is very similar to the (1, 1) mode, which is the first symmetric wavenumber 1 Rossby normal mode in an isothermal atmosphere. Similarly, the 4-day wave appears to correspond to the (2, 1) mode. The vertical structure of both waves agrees well with the theoretical expectation of free external w...