Impact of Lightning‐Induced Nitrogen Oxides Over and Around the Tibetan Plateau on the Tibetan Plateau Ozone Valley

Abstract

AbstractLightning‐induced nitrogen oxides (LNOx) can affect ozone (O3) through photochemical processes. However, the impact of LNOx on the Tibetan Plateau (TP) O3 valley, an area with a lower O3 column compared to surrounding areas, remains controversial. Prior to this study, the impact of monsoonal transport on LNOx and related effects on the TP O3 valley has been overlooked. The objectives of this study are to differentiate between locally generated LNOx and monsoon‐transported LNOx over the TP and to evaluate their impacts on tropospheric NOx vertical column density, tropospheric column O3, and O3 at different altitudes. The Weather Research and Forecasting model coupled with Chemistry model was used to replicate LNOx, NOx, and O3 over the TP during July 2010, for which nesting techniques and sensitivity experiments were implemented. The findings emphasize the importance of LNOx as a source of NOx in this region, with nonlocal lightning activity being the primary source. Conversely, the influence of locally generated LNOx on NOx levels over the TP is comparatively minor. Overall, LNOx contributes to an increase in O3 over the TP, but one order lower than the O3 depletion. The impact of LNOx on O3 varies across different altitude ranges; it is broadly “C” shaped, reflecting increase in O3 at near‐surface and in upper troposphere–lower stratosphere (UTLS) regions and decrease in the middle troposphere. The increase in surface‐level O3 over the TP is mainly caused by monsoon‐transported LNOx, while locally generated LNOx also plays a crucial role in O3 formation in the UTLS region.