Atmospheric Chemistry and Physics Direct satellite observation of lightning-produced NOx

Abstract. Lightning is an important source of NOx in the free troposphere, especially in the tropics, with strong impact on ozone production. However, estimates of lightning NOx (LNOx) production efficiency (LNOx per flash) are still quite uncertain. In this study we present a systematic analysis of NO2 col-umn densities from SCIAMACHY measurements over active thunderstorms, as detected by the World-Wide Lightning Lo-cation Network (WWLLN), where the WWLLN detection efficiency was estimated using the flash climatology of the satellite lightning sensors LIS/OTD. Only events with high lightning activity are considered, where corrected WWLLN flash rate densities inside the satellite pixel within the last hour are above 1 /km2/h. For typical SCIAMACHY ground pixels of 30 × 60 km2, this threshold corresponds to 180