Estimation of Lightning-Generated NOx in the Mainland of China Based on Cloud-to-Ground Lightning Location Data

Lightning-generated nitrogen oxides (LNOx) have a major influence on the atmosphere and global climate change. Therefore, it is of great importance to obtain a more accurate estimation of LNOx. The aim of this study is to provide a reference for the accurate estimation of the total LNOx in the mainland of China based on cloud-to-ground lightning (CG) location data from 2014 to 2018. The energy of each CG flash was based on the number of return strokes per CG flash, the peak current of each return stroke, and the assumed CG breakdown voltage. The energy of intracloud lightning (IC) was based on the estimated frequencies of IC and the assumed energy of each IC flash. Combining the energy of lightning and the number of nitric oxide (NO) molecules produced by unit energy (rho(no)), the total LNOx production in the mainland of China was determined. The LNOx in the mainland of China estimated in this study is in the range (0.157-0.321) x 10(9) kg per year [Tg(N) yr(-1)], which is on the high end of other scholars' works. Negative cloud-to-ground lightning (NCG) flashes produce the most moles of NOx, while positive cloud-to-ground lightning (PCG) flashes produce the least total moles of NOx. The breakdown voltage of PCG is greater than that of IC or NCG, while the latter has a greater output of LNOx.