STRATOSPHERIC NOY MEASUREMENTS ON THE NASA DC-8 DURING AASE-II

We survey measurements of stratospheric NO(y) on the NASA DC-8 during AASE II in early 1992. Emphasis is on correlations with other long-liv ed species: O3, N2O, and CH4. No cases of extremely high NO(y)/O3 rati os were seen in 1992. This suggests that denitrification at higher alt itudes was less pervasive than in 1989. Values of NO(y)/O3 in 1992 are comparable to, though perhaps lower than, those measured in 1989. The correlation of NO(y); with N2O changes over the course of the mission . Relative to the correlation for the whole season, low values of NO(y ) occur in February, most notably on the 22nd. The reason for the low NO(y) is unknown. It is generally too warm at DC-8 altitudes for the p resence of PSC particles, but denitrification at higher altitudes, fol lowed by descent, might account for the low values seen on 22 February . However, this may be unlikely since the NASA ER-2, flying during the same period, saw no evidence of denitrification at higher altitudes [ Loewenstein et al., 1993].