Abstract
Abstract. We estimate the concentration changes, caused by streamer discharge in sprites, of ozone and related minor species as odd nitrogen (NOx) and hydrogen (HOx) families in the upper stratosphere and mesosphere. The streamer has an intense electric field and high electron density at its head, where a large number of chemically-radical ions and atoms are produced through electron impact on neutral molecules. After its propagation, densities of minor species can be perturbed through ion-neutral chemical reactions initiated by the relaxation of these radical products. We evaluate the production rates of ions and atoms using an electron kinetics model and by assuming that the electric field and electron density are in the head region. We calculate the density variations mainly for NOx, Ox, and HOx species using a one-dimensional model of the neutral and ion composition of the middle atmosphere, including the effect of the sprite streamer. Results at the nighttime condition show that the densities of NO, O3, H, and OH increase suddenly through reactions triggered by the first atomic nitrogen and oxygen product, and electrons just after streamer initiation. It is shown that NO and NO2 still remain for 1 h by a certain order of increase with their source-sink balance, predominantly around 60 km; for other species, increases in O3, OH, HO2, and H2O2 still remain in the range of 40–70 km. From this affirmative result of long-time behavior previously not presented, we emphasize that sprites would have the power to impact local chemistry at night. We also discuss the consistency with previous theoretical and observational studies, along with future suggestions.
Highlights
Sprites are lightning-induced secondary discharges with both lateral and vertical scales of tens of kilometers appearing at the middle atmosphere all over the world
We estimate density variations of NOx, Ox, and HOx families on the basis of ion chemistry driven by non-thermal electron kinetics in sprite streamer
We evaluate chemically radical particle production by the electrons with an exact kinetic method
Summary
Sprites are lightning-induced secondary discharges with both lateral and vertical scales of tens of kilometers appearing at the middle atmosphere all over the world. The amount of ions and atoms produced is considered to be comparable to nes or larger, and is estimated to be ≈109 cm−3 at the altitudes of 40–50 km by assuming a scaling relation of nes∼N 2, with N being atmospheric gas density (Pasko et al, 1998). This corresponds to ≈1% of ozone density at this altitude range (Brasseur, 1999).
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