An assessment of Southern Hemisphere stratospheric NO(x) enhancements due to transport from the upper atmosphere

Abstract

Data from the Halogen Occultation Experiment (HALOE) are used to evaluate the contribution of upper atmospheric NO(x) to the stratospheric polar vortex. Using CH 4 and potential vorticity as tracers, an isolated region of enhanced NO(x) is shown to occur in the Southern Hemisphere (SH) polar vortex almost every spring from 1991-1996. The magnitude of this enhancement varies according to the A(P) auroral activity index. Up to half of the NO(x) in the mid-stratospheric SH polar vortex may be due to particle precipitation. The peak enhancement occurred in 1991 with a magnitude of 3-5% of the NO(y) source due to N 2 O oxidation.