Solar Influences on Stratospheric Circulation Patterns

The impact of the solar cycle on the NH winter stratospheric circulation is analyzed using
simulations of a Model of an idealized Moist Atmosphere (MiMA). By comparing solar minimum
periods to solar maximum periods, the solar impact on the stratosphere is evaluated: Solar
maximum periods are accompanied by warming of the tropics that extends into the midlatitudes
due to an altered Brewer Dobson Circulation. This warming of the subtropics and the altered
Brewer Dobson Circulation leads to an increase in zonal wind in midlatitudes, which is then
followed by a decrease in E-P flux convergence near the winter pole which extends the enhanced
westerlies to subpolar latitudes.
We use the transformed Eulerian mean framework to reveal the processes that lead to the
formation of this sub-polar zonal wind anomaly and its downward propagation from the top of the
stratosphere to the tropopause.