It is worthwhile noting that the model doesn't produce a QBO on its own, so the assimilation system must use the ingested atmospheric data to produce one in the output data. Easterlies are coloured yellow to blue and westerlies orange to red. The QBO is roughly between 10mb and 100mb in height extent. The wind regimes propagate down as time progresses. The period of the oscillation is 20 to 36 months with a mean of around 28 months.
Easterlies are generally stronger than westerlies.
Westerly winds last longer than easterly winds at higher levels while the converse is true at lower levels. The westerlies move down faster than the easterlies as shown by the steepness of the zero line. The transition between westerly and easterly regimes is often delayed between 30 and 50mb. There is considerable variability of the QBO in period and amplitude. Zonal mean wind as a function of time and latitude at 10mb.