Spatial and temporal evolution of future atmospheric reactive nitrogen deposition in China under different climate change mitigation strategies

Abstract. Atmospheric reactive nitrogen (Nr) deposition plays a crucial role in linking air pollution to ecosystem risks. Previous modeling studies have indicated that climate change and pollution controls jointly result in significant changes in Nr deposition in China. However, it remains unclear how future emission reductions will influence Nr deposition under different climate pathways. Here, we investigated the spatiotemporal evolution and driving factors of future Nr deposition under various national clean air and climate policies. We applied WRF-CMAQ and assessed the historical (2010s, 2010–2014) pattern and future changes of Nr deposition till the 2060s (2060–2064) in China, by combining two SSP-RCP global climate pathways and three national emission control scenarios. The results show that the implementation of clean air and carbon neutrality policies would greatly reduce oxidized nitrogen (OXN) deposition, mitigate the adverse perturbations of climate change, and reduce the outflow from Eastern China (EC) to the West Pacific. In North China (NC), the weakened atmospheric oxidation capacity (AOC) would elevate the response of OXN deposition to a 20 % abatement of emissions (expressed as the ratio of percentage change of deposition to emissions) from 82.6 % in the 2010s to nearly 100 % in the 2060s. In contrast, the response of RDN deposition to NH3 emissions would decline, likely attributable to a more NH3-rich condition. The outcomes of this work broaden scientific understanding on how anthropogenic actions of air quality improvement and carbon emission reduction would reshape the future Nr deposition and support effective policymaking to reduce associated ecological damages.