Energy of Rossby waves as a part of global atmospheric oscillations

Abstract

A data set of 4 years of daily ECMWF global operational analyses was projected onto normal modes which were constructed by the solution of the Laplace tidal equations including the effect of mean zonal flow and the vertical structure equation. A time-series analysis was set up to identify free Rossby waves and to quantify the energy distributions of free propagating, forced propagating, standing and quasi-stationary waves. 18 modes could be identified or evidence of their existence could be stated. The energy partition of free propagating waves varies from 43% in the case of the 16-day-wave down to about 5% in the case of higher indexed modes. The pure westward propagating modes are seen to be the more consistent with theory the higher their energy is.