NEW OBSERVATIONS OF THE NOY N2O CORRELATION IN THE LOWER STRATOSPHERE/

During the Airborne Arctic Stratospheric Expedition II (AASE II), Sept ember 1991 through March 1992, in situ measurements of reactive nitrog en (NO(y)) and N2O were made in the Northern Hemisphere lower stratosp here. We present an analysis of this new data and compare it with resu lts from similar data taken during AASE in the winter of 1989. In the Northern Hemisphere there is a consistent linear correlation of N2O an d NO(y) which shows no interannual variation. Cases of departure from a linear correlation are examined and classified as being due to denit rification (NO(y) loss) or sampling air from a region where the photoc hemical lifetime of NO(y) is decreased. The latter case was observed f or the first time in the winter of 1992.