Nick Pedatella - Upper atmosphere variability during sudden stratosphere warmings

Speaker: Nick Pedatella, National Center for Atmospheric Research (NCAR)

Abstract: Sudden stratosphere warmings (SSWs) are associated with a rapid temperature increase in the wintertime polar stratosphere, as well as a deceleration, and potential reversal, of the normally eastward high latitude stratospheric winds. Perhaps surprisingly, although SSWs themselves are primarily a high latitude stratospheric phenomenon, recent results have demonstrated the global impact of SSWs on the middle and upper atmosphere. The variability in the middle and upper atmosphere can exceed 100%, and SSWs thus represent a significant source of upper atmosphere variability. Using numerical simulations from the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) and Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) I will present recent results that demonstrate the mechanisms by which SSWs introduce variability into the middle and upper atmosphere, with a particular emphasis on the source of variability in the low latitude ionosphere. Results for both free-running (i.e., generic) and real SSW simulations will be presented. Current capabilities for simulating SSWs are also illustrated through comparing real SSW simulations with observations.