Theoretical interpretation of N 2 O 5 measurements

Recent measurements by Webster et al. [1990] have confirmed quantitatively the chemistry controlling the night‐time decay of NO 2 . Simple equations describing the night‐time behaviour of NO 2 and N 2 O 5 are presented here. With measurements of the night‐time ozone and NO 2 concentrations, these equations can be used to predict the amount of N 2 O 5 produced at any time during the night. In this way the N 2 O 5 night‐time emission measurement of Roscoe [1982], Kunde et al. [1988] and sunrise measurements of the ATMOS experiment [Rinsland et al., 1989] are all used to test theory. The measurements are found to be both self consistent and confirm our understanding of night‐time NO 2 conversion to N 2 O 5 . The variation of N 2 O 5 by a factor of two between measurements is found to be consistent with theory.