Relationships between climate change, natural variability, and stratospheric ozone in the Arctic winter and spring

Observations of the stratosphere suggest that changes in temperature are caused by ozone loss and by greenhouse gas increases, but that regional trends can be dominated by dynamical variability. This is particularly true of the Arctic region, where year-to-year variations in planetary wave forcing (and possibly other factors) appear to strongly modulate the possibility for chemical ozone loss. This study will examine temperature and ozone change between about 1960 and 2008 in the Arctic using observations, meteorological analyses, and the Goddard Earth Observing System Chemistry-Climate Model (GEOS CCM). Analysis of observations will re-examine the suggestion of Pawson and Naujokat (JGR, 1999) that there may be a tendency for dynamically undisturbed winters to become colder between 1960 and 2000. Controlled experiments with the GEOS CCM allow examination of the significance of this apparent trend and isolation of possible mechanisms for it.