The 26-Month Oscillation in Zonal Wind and Temperature

Abstract

Harmonic analysis of mean monthly zonal wind and temperature data,after removing the annual cycle, have shown the existence of the 26-month oscillation in the equatorial stratosphere. The oscillation in temperature extends to temperate and polar latitudes, while in zonal wind it is insignificant beyond 25N. The amplitude of the 26-month oscillation in temperature follows a meridional wave pattern with an approximate wavelength of about 30 deg of latitude. The phase of the 26-month oscillation in both zonal wind and temperature progresses downward, at equatorial latitudes, with a speed a little less than 1 km per month. The oscillation in temperature at the position of the tropical amplitude maximum is approximately out of phase with the oscillations at high level equatorial latitudes and at temperate and polar latitudes.