Simultaneous spectroscopic determination of the latitudinal, seasonal, and diurnal variability of stratospheric N₂O, NO, NO₂, and HNO₃

The importance Of NO x compounds to stratospheric chemistry has been clearly established. We report below on a program to measure latitudinal, seasonal, and diurnal variations in stratospheric N 2 O, NO, NO 2 , and HNO 3 amounts. Through the use of airborne Fourier transform absorption spectroscopy, we determine simultaneously column amounts above 12 km of the four molecules listed above. Nitrous oxide (N 2 O) is found to have a fairly uniform distribution with latitude and season, with a stratospheric column abundance of 8.1 × 10 17 molecules cm −2 . Nitric oxide (NO) amounts are shown to decrease with increasing latitude in winter. A 50% decrease in high latitude winter amounts is observed as compared with low latitude values near 3.0 × 10 15 molecules cm −2 . Nitrogen dioxide (NO 2 ) stratospheric amounts increase in summer with increasing latitude. Equatorial values are near 3.0 × 10 15 molecules cm −2 above 12 km. A factor of 3–4 increase in higher latitude summertime NO 2 , as compared to winter NO 2 , is observed. Nitric acid (HNO 3 ) amounts show a general increase toward higher latitudes and a marked increase in mid‐latitude winter as compared to summer. Winter amounts may be highly variable with a value near 1.0 × 10 16 molecules cm −2 .