WACCM climate chemistry sensitivity to sprite perturbations

Particular emphasis has been given to sprites, with models and observations suggesting a capability of perturbing atmospheric nitrogen oxides at a local level, as it is known to occur for tropospheric lightning and laboratory air discharges. However, it is as yet unknown whether sprites can be a relevant source of nitrogen oxides for the upper atmosphere.

In this paper, we study the sensitivity of the Whole Atmosphere Community Climate Model (WACCM) to sprite-like nitrogen oxide perturbations. We take a top-down approach to estimate what magnitude sprite perturbations should have to become significant as compared to other relevant atmospheric processes and study the sensitivity of the model response within the given uncertainties. We show that, based on current predictions by sprite streamer chemistry models, sprites can perturb Tropical NOx at 70 km altitude between 0.015 ppbv (buried in the background variability) and 0.15 ppbv (about 20%), adopting a local NOx production per sprite of 1.5·10²³ and 1.5·10²⁴ molecules respectively at this altitude.