Winter stratospheric circulation and the equatorial QBO Original Research Article

Composite analysis of the winter stratospheric circulation with respect to the phase of the equatorial QBO is made by using the NCEP/NCAR reanalysis data over 40 years (1958–1997). It is found that the composite difference in the Southern Hemisphere is large not in midwinter but in early spring (November). It is also found that the level of the QBO reference which makes the large composite difference in the Southern Hemisphere is higher than in the Northern Hemisphere.