IAMAS 2005, Beijing, PR China, 2-11 August 2005

Possibility of NOx production by transient luminous events studied in a coupled ion-neutral chemical model

C.-F. Enell¹, P. Verronen², A. Seppälä², E. Turunen¹, Th. Ulich¹

¹Sodankylä Geophysical Observatory, Sodankylä, Finland,
²Finnish Meteorological Institute, Geophysical Research Division, Helsinki, Finland.

Abstract

Transient luminous events (TLEs), such as sprites and elves, occur on timescales too short to produce significant enhancements of reactive neutral species through mechanisms traditionally considered in ionospheric science. However, it is known that reactions of the excited states of N2 observed in TLEs may be major sources of NOx. In order to answer the question of whether TLEs affect middle-atmospheric chemistry or not, these excited-state reactions must be taken into account.

The Sodankylä Ion Chemistry (SIC) model is a 1-dimensional coupled ion-neutral model with a comprehensive chemical scheme. SIC is well suited to studying the chemical effects of short-term local forcing and new reactions can be added rather easily. In this paper we discuss the production of NOx due to the reactions mentioned above, as compared with other channels of production in the upper atmosphere, and test the sensitivity of the SIC model to the potentially large uncertainties in the scheme of excited-state reactions and their reaction rates.