Springtime stratospheric NO 2 in Antarctica

We present springtime measurements of column amounts of stratospheric nitrogen dioxide measured by ground based absorption spectroscopy from Scott Base, Antarctica (77.8°S, 166.7°E). There is a rapid build up from <1 × 10 15 molecules cm −2 at the end of August to about 5 × 10 15 molecules cm −2 by mid October. The period covered is the transition time between winter night, and summer day; and in general the ‘overnight’ decay of NO 2 is small. The decay is most significant at times when the number of hours of sunlight per day exceeds 12 hours. There are large day to day variations in column amounts which indicate that transport is a significant factor.