High‐latitude stratospheric NO₂ and HNO₃ over Fairbanks (65°N) 1992–1994

Column measurements of NO 2 and HNO 3 were made over Fairbanks, Alaska, between August 1992 and April 1994. The seasonal minimum of the NO 2 column occurs in late December, while the minimum of the HNO 3 column is in early August. The high HNO 3 column amounts observed in February as opposed to the lower winter value predicted by gas phase two‐dimensional models suggest that the storage reservoir species N 2 O 5 does not accumulate during the winter. Instead, it appears to be converted to HNO 3 on sulfate aerosols. Three‐dimensional model calculations which include the heterogeneous reaction of N 2 O 5 with aerosols simulate the anticorrelation relationship between NO 2 and HNO 3 well for the summer and predict the magnitude of the NO 2 maximum but overestimate the HNO 3 minimum.