Enhanced NO(x) by lightning in the upper troposphere and lower stratosphere inferred from the UARS global NO₂ measurements

This paper reveals a possible connection between lightning activity and the UARS NO₂ data on a global scale. NO₂ measured by the Halogen Occulation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) is analyzed for the entire year of 1993 and compared to the seasonal and global lightning distributions inferred from the Optical Transient Detector (OTD). The results suggest a link between lightning activity and observed high levels of NO₂ in the upper troposphere and lower stratosphere. Enhanced NO₂ mixing ratios significantly above the background level are consistently found in areas of elevated lightning activity. This relation is strongest in the tropical regions during the summer and spring months of the Northern and Southern Hemispheres. Moreover, the results show that background levels of NO₂ mixing ratios generally correspond to areas of little or no lightning activity.