New Publication

Our paper The influence of major sudden stratospheric warming and elevated stratopause events on the effects of energetic particle precipitation in WACCM was published in the Journal of Geophysical Research Atmospheres. The main result of the paper is that WACCM demonstrates a very strong relationship between the seasonal timing of sudden stratospheric warming (SSW) and elevated stratopause (ES) events and the amount of NO_x that is transported to the stratosphere following the SSW or ES event.

Abstract
We investigate the influence of major sudden stratospheric warming (SSW) and elevated stratopause (ES) events in the Northern Hemisphere winter on the transport of NO_x produced by energetic particle precipitation (EPP) from the mesosphere–lower thermosphere to the stratosphere using the Whole Atmosphere Community Climate Model (WACCM). Increases in NO_x following a major SSW and/or ES event are in excess of 100% compared to winters when no major SSW or ES event occurred. The increase in NO_x is attributed to an increase in the descending branch of the residual circulation (w^*) following the event. The timing of the event strongly affects the amount of NO_x that descends to the stratosphere: the earlier the event occurs, the more NO_x descends to the stratosphere. We also quantify the amount of NO_x produced by EPP descending to the stratosphere in each winter and find that the largest increases in NO_x are in years that have a major SSW followed by an ES event early in the season (December or early January). The strength of w^* following an event shows a very strong seasonal dependence and explains why the timing of the event affects the transport of NO_x.