Stratospheric nitrous oxide distribution in the southern hemisphere

Nitrous oxide measurements were made in the southern hemisphere (latitude, 42°S to 72°S) as part of the Airborne Antarctic Ozone Experiment (AAOE) in late winter and early spring 1987, covering the altitude range 14–21 km. This paper reports on N 2 O measurements made by the airborne tunable laser absorption spectrometer (ATLAS), which was flown on board the NASA ER‐2 aircraft. Average vertical N 2 O profiles at latitudes 72°S, 54°S, and 42°S are presented and compared, when possible, with equivalent summer profiles. Latitudinal gradients of N 2 O on isentropic surfaces are presented and discussed in terms of their implications about the inhibition of horizontal mixing near the polar vortex. Finally, a large‐scale distribution of N 2 O for the region 72°S to 42°S latitude is presented. The reader is directed to the note added in proof regarding the recent recalibration of this data set.