Kunihiko Kodera

Meteorological Research Institute, Tsukuba, Japan

Abstract:

The dynamical impact of the 11-year solar cycle is investigated with the focus on the
stratopause region where solar ultraviolet heating is greatest. The results of the analysis
suggest that in a climatological mean state, the stratopause circulation evolves from a
radiatively controlled state to one dynamically controlled during winter in both hemispheres.
The solar cycle effect appears as a change in the balance between the radiatively and
dynamically controlled states. The radiatively controlled state lasts longer during the solar
maximum phase and the stratopause subtropical jet reaches a higher speed. The large
dynamical response to relatively weak radiative forcing may be understood by the bi-modal
nature of the winter atmosphere due to interaction with meridionaly propagating planetary
waves and zonal-mean zonal winds.