Further evidence in stratospheric-tropospheric coupling: Biennial oscillations in the tropical total cloud cover

An analysis of monthly mean total cloud cover fractions in the tropics showed the existence of a quasi-biennial oscillation in total cloud cover. The amplitude of the oscillation is between 1 and 2.5 percent in zonal total cloud cover fractions, over the equatorial and southern latitudes. This oscillation is also compared with the corresponding oscillations in zonal mean stratospheric temperatures. The QBO in the tropical total cloud cover is superimposed on longer-term fluctuations (trends) which are discussed in the text.