The QBO is a dominant interannual
variation in the equatorial stratosphere.
It is characterized as periodic variations of the easterly and westerly zonal-mean zonal wind with the period of about 2 year (e.g., Baldwin et al. 2001, Review of Geophysics).
click figures to see larger ones.
Zonal wind observed at Singapore
About the data
About the index
A representation of the QBO is derived from the monthly-mean zonal wind data,
by following the method introduced by Wallace et al. (1993; Journal of the Atmospheric Sciences).
- The data is deseasonalized by subtracting the monthly climatology.
- First two principal components (PC1 and PC2) are derived from
the EOF analysis based on the covariance matrix at each levels.
- The data and EOFs used are from January 1976 to April 2017 (as of 8 June 2017).
Scatter plots of normalized PC1 and PC2 at 4-year intervals
Created: Jun. 05, 2017 by Eriko Nishimoto