Invited Speaker: Dave Thomson (Colorado State University) and Joanna Haigh (Imperial College, London)

The stratosphere has long been known to be strongly influenced by tropospheric dynamics. In the last decade however, numerous studies have presented evidence that the coupling also acts in the opposite direction and that the middle atmosphere plays an active role in surface weather and climate. The stratosphere also affects the troposphere through cross-tropopause radiative and chemical fluxes. Many outstanding questions remain regarding the dynamical and physical mechanisms involved, their evolution under climate change, and the impact of the stratosphere on forecast skill on the seasonal to centennial timescales. This session calls for contributions that address such questions. The session will also consider the role of solar variability on surface climate and especially the role the stratosphere plays, if any, in communicating this signal to the troposphere.