Stratospheric nitrogen dioxide observed by ground‐based and balloon‐borne techniques at Syowa Station (69.0°S, 39.6°E)

Seasonal variation of vertical column density of stratospheric NO 2 was determined for the period of March 1983 to January 1984 by means of ground‐based visible absorption spectroscopy at Syowa Station (69.0°S, 39.6°E), Antarctica. The winter minimum of about 1×10 15 cm −2 and the summer maximum of 7×10 15 cm −2 were observed. These values are nearly equal to, or a little bit smaller than, those observed at northern high latitudes. The nighttime decay of column density was small from autumn to early spring. A rapid increase in column density occurred at the end of September before the minimum of total ozone content in mid‐October. This behavior suggests that both dynamical and photochemical processes may be involved in the Antarctic ozone depletion. The vertical profile of stratospheric NO 2 in early summer in Antarctica was revealed by three balloon‐borne measurements over Syowa Station in November 1982 and 1983. Above 25 km altitude, these profiles are basically identical to those observed at middle and high latitudes in the northern hemisphere. In the lower stratosphere below 25 km, variability in NO 2 density seems to be large due to dynamical effects.