NEw observations of the NO_y/N₂O correlation in the lower stratosphere

Abstract

During the Airborne Arctic Stratospheric Expedition II (AASE II), September 1991 through March 1992, in situ measurements of reactive nitrogen (NO y ) and N 2 O were made in the Northern Hemisphere lower stratosphere. We present an analysis of this new data and compare it with results from similar data taken during AASE in the winter of 1989. In the Northern Hemisphere there is a consistent linear correlation of N 2 O and NO y which shows no interannual variation. Cases of departure from a linear correlation are examined and classified as being due to denitrification (NO y loss) or sampling air from a region where the photochemical lifetime of NO y is decreased. The latter case was observed for the first time in the winter of 1992.