The first nitrous acid (HONO) observation was conducted in Kunming of Yunnan Province, from April to May 2021 with frequent ozone (O₃) pollution events. To evaluate the impact of HONO on O₃, the WRF-Chem model simulations were conducted, with two cases including or excluding potential HONO sources. Based on the comparison between simulations and the corresponding observations, it was found that the application of the MEIC inventory (version 2020) could reasonably simulate HONO, nitrogen dioxide (NO₂), O₃ and fine particulate matter (PM_2.5) in urban Kunming. The additional HONO sources noticeably enhanced atmospheric oxidation capacity in Kunming and accelerated the hydroxyl radical (OH) production rate, leading to an O₃ enhancement of (2–6)×10⁻⁹ with the corresponding percentage enhancement of 2%–8% at the Kunming site within the height of 0–4 km and an O₃ enhancement of (4–7)×10⁻⁹ near the ground at the Kunming site and its surrounding area. The O₃-VOCs-NO_x sensitivity was also influenced by the potential HONO sources. This study deepened the understanding of HONO, atmospheric oxidation capacity and O₃ formation in the Yunnan-Guizhou Plateau, and could be helpful for regional O₃ pollution control. 

于2021年4—5月的云南省臭氧(O₃)污染事件频发时段, 在昆明市开展首次气态亚硝酸(HONO)观测, 并结合WRF-Chem空气质量模式, 评估添加HONO潜在来源与否对O₃浓度的影响。模拟结果表明, 使用2020年MEIC清单能较好地模拟昆明市的HONO、二氧化氮(NO₂)、O₃和细颗粒物(PM_2.5)等污染物。HONO潜在来源显著增强了大气氧化性和羟基自由基(OH)的生成速率, 引起昆明市距地面4 km范围内O₃增量为(2~6)×10^⁻9 (相应增幅约2%~8%)、近地面O₃增量为(4~7)×10^⁻9, 并在一定程度上影响O₃-VOCs-NO_x的敏感性。研究结果可加深对云贵高原地区HONO、大气氧化性及O₃生成的认识, 为区域O₃污染治理提供参考。