In the link you provided in 202 it is written:

>Fig. 4.56. Schematic of the relationship of Kelvin waves and Rossby-gravity waves in the equatorial zone. In all of the diagrams in this figure, the black line shows the vertical profile of the near equatorial zonal wind (westerlies are positive) in the upper troposphere and lower stratosphere. The Kelvin waves (red) are propagating upwards through the atmosphere transporting westerly momentum. The Rossby-gravity waves (blue) are also propagating upwards, taking easterly momentum with them.

This is my biggest problem with the theories about QBO. If I look at the images than the QBO seems to be a result of a downward movement not of an upward movement.