Impacts of climate change and emissions on atmospheric oxidized nitrogen deposition over East Asia

Abstract

<p><strong>Abstract.</strong> A multi-model ensemble of Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) simulations are used to study the atmospheric oxidized nitrogen (NO<sub>y</sub>) deposition over East Asia under climate and emission changes projected for the future. Both dry and wet NO<sub>y</sub> deposition shows significant decreases in the 2100s under RCP 4.5 and RCP 8.5, primarily due to large anthropogenic emission reduction over both land and sea. However, in the near future of the 2030s, both dry and wet NO<sub>y</sub> deposition increases significantly due to continued increase in emissions. The individual effect of climate or emission changes on dry and wet NO<sub>y</sub> deposition is also investigated. The impact of climate change on dry NO<sub>y</sub> deposition is relatively minor, but the effect on wet deposition, primarily caused by changes in precipitation, is much higher. For example, over the East China Sea, wet NO<sub>y</sub> deposition increases significantly in summer due to climate change by the end of this century under RCP 8.5, which may subsequently enhance marine primary production. Over the coastal seas of China, as the transport of NO<sub>y</sub> from land becomes weaker due to the decrease of anthropogenic emissions, the effect of ship emission and lightning emission becomes more important. On average, seasonal mean total NO<sub>y</sub> deposition is projected to be enhanced by 24–48 % and 3 %–37 % over Yellow Sea and East China Sea, respectively, by the end of this century. Therefore, continued control of both anthropogenic emission over land and ship emissions may reduce NO<sub>y</sub> deposition to the Chinese coastal seas.</p>