2007 Volume 85 Issue 6 Pages 889-898
The effect of the Quasi-Biennial Oscillation (QBO) and the El Niño Southern Oscillation (ENSO) on the 11-year solar cycle modulation of the winter-mean North Atlantic Oscillation (NAO) is examined through analysis of observational data from 1958 to 2000. It is found that the solar cycle modulation of the NAO is more strongly enhanced in the westerly phase of the 50-hPa QBO wind and the cold phase of ENSO, although separation of these effects is statistically difficult. On these phases, the signal of the winter-mean NAO extends more to the upper stratosphere and summer-AO reappears more strongly in high solar years, whereas the signal is weaker throughout in low solar years.
