Parameterisation of lightning in a general circulation model with interactive chemistry

In the upper troposphere, lightning strokes are the dominant source of nitrogen oxides (NOx). Estimates of the global production of NOx by lightning vary broadly from 2 to 8 Tg per year (expressed as N equivalent). Though this represents only around 10% of the global nitrogen oxides emissions, the impact on tropospheric chemistry is large because of the long lifetime of NOx in this region of the atmosphere, making it much more efficient at catalyzing ozone production than equivalent surface emissions. The horizontal and vertical distributions of the emissions are equally important to their impact. As part of the ongoing development of a general circulation model with interactive chemistry, several lightning parameterisations are compared in terms of the response in NOx, ozone distributions.