The effects of aerosol-radiation interactions (ARI) are not only important for regional and global climate, but they can also drive particulate matter (PM) pollution. In this study, the ARI contribution to the near-surface fine PM (PM_2.5) concentrations in the Guanzhong Basin (GZB) is evaluated under four unfavorable synoptic patterns, including “north-low”, “transition”, “southeast-trough”, and “inland-high”, based on WRF-Chem model simulations of a persistent heavy PM pollution episode in January 2019. Simulations show that ARI consistently decreases both solar radiation reaching down to the surface (SWDOWN) and surface temperature (TSFC), which then reduces wind speed, induces sinking motion, and influences cloud formation in the GZB. However, large differences under the four synoptic patterns still exist. The average reductions of SWDOWN and daytime TSFC in the GZB range from 15.2% and 1.04°C in the case of the “transition” pattern to 26.7% and 1.69°C in the case of the “north-low” pattern, respectively. Furthermore, ARI suppresses the development of the planetary boundary layer (PBL), with the decrease of PBL height (PBLH) varying from 18.7% in the case of the “transition” pattern to 32.0% in the case of the “north-low” pattern. The increase of daytime near-surface PM_2.5 in the GZB due to ARI is 12.0%, 8.1%, 9.5%, and 9.7% under the four synoptic patterns, respectively. Ensemble analyses also reveal that when near-surface PM_2.5 concentrations are low, ARI tends to lower PM_2.5 concentrations with decreased PBLH, which is caused by enhanced divergence or a transition from divergence to convergence in an area. ARI contributes 15%–25% toward the near-surface PM_2.5 concentrations during the severe PM pollution period under the four synoptic patterns.

气溶胶-辐射相互作用（ARI）的影响不仅对于区域和全球气候非常重要，而且还可能导致颗粒物（PM）污染。在这项研究中，ARI对近地表精细PM（PM _2.5）在WRF-Chem模型模拟的基础上，根据四种不利天气模式对关中盆地（GZB）的浓度进行了评估，包括“北低”，“过渡”，“东南低谷”和“内陆高”。 2019年1月持续严重的PM污染事件。模拟显示，ARI持续降低到达地表的太阳辐射（SWDOWN）和地表温度（TSFC），从而降低风速，引起下沉运动并影响GZB中的云形成。但是，在四种天气模式下仍然存在较大差异。GZB中SWDOWN和日间TSFC的平均减少分别在“过渡”模式下为15.2％和1.04°C，在“北低”模式下分别为26.7％和1.69°C。此外，ARI抑制了行星边界层（PBL）的发展，PBL高度（PBLH）的降低从“过渡”模式的18.7％到“北低”模式的32.0％不等。白天近地表PM的增加在四种天气模式下，由ARI引起的GZB中的_2.5分别为12.0％，8.1％，9.5％和9.7％。集合分析还显示，当近地表PM _2.5浓度较低时，ARI倾向于降低PM _2.5浓度，而PBLH降低，这是由于区域中的散度增加或从散度向收敛过渡而引起的。在四种天气模式下，在严重PM污染期间，ARI对近地表PM _2.5浓度的贡献为15％至25％。