Accurate prediction of PM, its optical properties and dominant chemical components are essential for air quality studies. In this study, we investigated the effects of two gas phase chemical schemes coupled with three aerosol mechanisms on the simulated PM mass concentration in Delhi using the Weather Research and Forecasting model with Chemistry module (WRF-Chem). The model was employed to cover the entire northern region of India at 10 km horizontal spacing and results were compared with comprehensive field data set on dominant PM chemical compounds from the Winter Fog EXperiment (WiFEX) at the Indira-Gandhi International Airport, New Delhi, and surface PM observations in Delhi (17 sites), Punjab (3 sites), Haryana (4 sites), Uttar Pradesh (7 sites) and Rajasthan (17 sites). The Model for Ozone and related Chemical Tracers (MOZART) gas-phase chemical mechanism coupled with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) aerosol scheme were selected in the first experiment as it is currently employed in the operational air quality forecasting system of Ministry of Earth Sciences (MoES), Government of India. Other two simulations were performed with the MOZART gas phase chemical mechanism coupled with the Model for Simulating Aerosol Interactions and Chemistry (MOZART-MOSAIC), and Carbon Bond 5 (CB-05) gas mechanism coupled with the Modal Aerosol Dynamics Model for Europe/Secondary Organic Aerosol Model (CB05 - MADE/SORGAM) aerosol mechanisms. The evaluation demonstrated that chemical mechanisms affect the evolution of gas-phase precursors and aerosol processes which in turn affect the optical depth and overall performance of the model for PM. All the three chemical schemes underestimate the observed concentrations of major aerosol composition and precursor gases over Delhi. Comparison with observations suggests that, the simulations using MOZART gas-phase chemical mechanism with MOSAIC aerosol scheme performed better in simulating aerosols over Delhi and its optical depth over the IGP.

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评估德里 WRF-Chem 细颗粒物 (PM2.5) 模拟对化学机制的敏感性

准确预测 PM、其光学特性和主要化学成分对于空气质量研究至关重要。在本研究中，我们使用带有化学模块的天气研究和预报模型 (WRF-Chem) 研究了两种气相化学方案与三种气溶胶机制相结合对德里模拟 PM 质量浓度的影响。该模型以 10 公里的水平间距覆盖了印度整个北部地区，并将结果与​​新德里英迪拉-甘地国际机场冬季雾实验 (WiFEX) 的主要 PM 化合物的综合现场数据集进行了比较。德里（17 个站点）、旁遮普邦（3 个站点）、哈里亚纳邦（4 个站点）、北方邦（7 个站点）和拉贾斯坦邦（17 个站点）的地表 PM 观测。第一次实验选择了臭氧及相关化学示踪剂模型（MOZART）气相化学机制与戈达德化学气溶胶辐射和传输（GOCART）气溶胶方案相结合，因为它目前已应用于该部的空气质量预报系统中印度政府地球科学部 (MoES)。另外两个模拟是使用 MOZART 气相化学机理与模拟气溶胶相互作用和化学模型 (MOZART-MOSAIC) 相结合，以及碳键 5 (CB-05) 气体机理与欧洲/中学模态气溶胶动力学模型相结合进行的有机气溶胶模型（CB05 - MADE/SORGAM）气溶胶机制。评估表明，化学机制影响气相前体和气溶胶过程的演化，进而影响 PM 模型的光学深度和整体性能。所有三种化学方案都低估了德里上空主要气溶胶成分和前体气体的观测浓度。与观测结果的比较表明，使用 MOZART 气相化学机制和 MOSAIC 气溶胶方案进行的模拟在模拟德里上空的气溶胶及其 IGP 上空的光学深度方面表现更好。