The solar and equatorial QBO influences on the stratospheric circulation during the early northern‐hemisphere winter

A case study was conducted to investigate the mechanism of how the solar cycle and the equatorial quasi‐biennial oscillation (QBO) influence the stratospheric circulation during the Northern‐Hemisphere winter. It was found that the solar and QBO influences on the stratospheric jet exist rather independently in the upper stratosphere during December. The mean‐zonal wind anomalies produced in early winter persist by deformation until late winter through wave‐mean flow interactions with planetary waves. The modulation effect of the solar influence by the QBO [Labitzke, 1987] takes place during this process.