Arctic and Antarctic polar winter NO_<i>x</i> and energetic particle precipitation in 2002–2006

Abstract

We report GOMOS nighttime observations of middle atmosphere NO 2 and O 3 profiles during eight recent polar winters in the Arctic and Antarctic. The NO 2 measurements are used to study the effects of energetic particle precipitation and further downward transport of polar NO x . During seven of the eight observed winters NO x enhancements occur in good correlation with levels of enhanced high‐energy particle precipitation and/or geomagnetic activity as indicated by the A p index. We find a nearly linear relationship between the average winter time A p index and upper stratospheric polar winter NO 2 column density in both hemispheres. In the Arctic winter 2005–2006 the NO x enhancement is higher than expected from the geomagnetic conditions, indicating the importance of changing meteorological conditions.