Estimation of Lightning-Generated NO_x in Inland China by Comparison of the Lightning Activity and NO₂ Distribution over the Tibetan Plateau

In order to better understand the relationship between lightning activities and nitrogen oxide (LNO_x) in the troposphere, and estimate the lightning-generated NO_x production in China more precisely, monthly means of lightning density and tropospheric NO₂ vertical column densities (VCD) from the Tibetan Plateau, where there is a sparse population and underdeveloped industrial activity, are analyzed in terms of their distribution and correlation. The data are obtained from LIS (Lightning Imaging Sensor) measurements and GOME-2 (the Global Ozone Monitoring Experiment-2) from January 2009 to February 2012. The LNO_x production in inland China is estimated based on Beirle's LNO_x estimation method. The results show that the tropospheric NO_x over the selected region of inland China is influenced little by anthropogenic sources. Lightning densities over the region are in reasonable agreement with tropospheric NO₂ in terms of annual, spatial and seasonal variations. Combined with the correlation coefficient of 0.84 calculated by linear fitting, LNO_x production in inland China is evaluated as 0.15 (0.03-0.38) Tg(N) a^-1. It is indicated that the Tibetan Plateau is an ideal area to study LNO_x. The conclusion further reduces the estimation uncertainty range of LNO_x production in previous work, helping us to more clearly recognize the important role of lightning in climate change in China.