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Vertically Distributed Effects of Stratospheric Polar Vortex Disturbances on Composition during Arctic Winter

Major sudden stratospheric warmings (SSWs) illustrate clearly the coupling of atmospheric regions from the troposphere through the mesosphere, and have profound implications for variability in atmospheric composition.  Less extreme disturbances to the polar vortex also illustrate vertical coupling and influence composition.  Six of the strongest, most prolonged SSWs on record have occurred in the past decade, with only two other comparable events in the past 34 years; five of those have been since the launch of the Microwave Limb Sounder (MLS) on NASA’s Aura satellite.  This talk focuses on the composition effects of SSWs and smaller stratospheric polar vortex disturbances in three areas:  (1) Anomalous transport related to the stratopause breakdown and reformation during prolonged SSWs, (2) Effects of lower stratospheric vortex disturbances in early winter on transport and chemical ozone loss, and (3) Relationships between stratospheric and upper tropospheric/lower stratospheric circulation and transport changes during SSWs.  MLS data, meteorological (re)analyses, and results from the CMAM30 “specified dynamics” chemistry climate model simulation are used to study these processes.  Some examples will be presented from the 2012/2013 and 2013/2014 Arctic winters.