This is one of the animations that are of interest showing wind speeds at various altitudes and latitudes :


Taken from this site:

The animation is kind of hypnotic, but watch as the North and South hemispheres alternately appear to push volumes of air toward the equator, while along the equator, the QBO of 2.33 year period descends from the stratosphere. The QBO cycle is the feature that really impacts the ENSO as it is more zonal, i.e. east/west.