Lightning: A possible source of stratospheric odd nitrogen

It is argued on the basis of a two-dimensional stratospheric model that upward transport of oxides of nitrogen produced by lightning in the tropical troposphere can significantly enhance the concentrations of NOY, the composite of all forms of odd nitrogen, in the lower stratosphere. The impact can be as large as a factor of 10 at 22 km near the equator, dropping to less than 50% above 30 km. Inclusion of the lightning source of NOY in the model results in improved agreement with available satellite data for the sum of NO₂ and HNO₃. Lightning is important even if only 5% of the nitrogen oxides produced enters the stratosphere. This amounts to ∼2 × 10⁵ t N yr^-1 and is equivalent to about one third of the global production from in situ photochemical reaction of N₂O with O(¹D).