The influence of the 11-year solar cycle on the quasi-biennial oscillation

[ 1] The zonally averaged CHEM2D photochemical-dynamical middle atmosphere model is used to investigate the effect of the 11- year cycle in solar ultraviolet ( UV) irradiance on the quasi- biennial oscillation ( QBO) in equatorial lower stratospheric zonal wind. Model calculations show the duration of the westerly ( easterly) phase of the modeled QBO is similar to 1 month shorter ( longer) at solar maximum than at solar minimum. This effect is most apparent when the modeled QBO period is 28 months, and it is dependent on the magnitude of the imposed solar UV variations. The model results also show that a realistic simulation of the semi- annual oscillation in equatorial zonal wind is necessary to produce solar cycle changes in QBO behavior. This is the first fully interactive modeling study to show that changes in solar UV can influence the behavior of the QBO, and lends support to the current working theory of sun- climate connections.