NOx production by lightning estimated with GOME Original Research Article

Nitrogen oxides (NO + NO2=NOx) are important trace gases in the troposphere with impact on human health, climate and atmospheric chemistry, e.g. through their role in ozone production. Therefore a better understanding of the strength of the various sources (fossil fuel combustion, biomass burning, soil emissions, lightning) is desirable. NOx produced by lightning contributes approx. 12%, i.e. 5 (2–20) Tg [N]/year [Atmos. Environ. 31 (1997) 1735; EULINOX – The European Lightning Nitrogen Oxides Project. DLR – Forschungsbericht 2000-28, 2000], of the totally produced nitrogen oxides. An uncertainty of one order of magnitude remains. Here we present an estimation of lightning produced NOx using satellite data. Lightning activity is monitored by the Lightning Imaging Sensor since November 1997. The same time span is also covered by NO2 measurements from the Global Ozone Monitoring Experiment. This allows a statistical approach. In this study we relate lightning frequency and the tropospheric vertical column densities of NO2 over Central Australia, where other NOx sources have only minor contribution. By analyzing the correlation of lightning activity with the vertical column densities of NO2 we estimate the globally produced lightning NOx to be ∼2.8 (0.8–14) Tg [N]/year. Despite the many uncertainties involved in NO2 retrieval (e.g. profile information, cloud influence), this value shows a good agreement with literature.