In north India (about 30,000 km² area), October–November months witness crop residue burning (CRB). This study aims to assess the impact of CRB emissions on PM_2.5 and secondary aerosol (SA) at distances far from the sources. Chemical transport model, WRF-Chem (with chemical mechanisms, RADM2 and MADE/SORGAM), was applied to a domain of 840 × 840 km² (centered around Delhi) with inputs of emissions of anthropogenic sources of EDGAR-HTAP and fire inventory from the National Centre for Atmospheric Research, USA. In parallel, measurements of PM_2.5 and its constituents, CO, and NO₂ were undertaken in Delhi and Kanpur. The model underestimated PM_2.5 and showed poor predictions (r < 0.15) with insignificant formation of secondary organic aerosol (SOA) (< 1% in PM_2.5). To improve the model, a linear regression-based hybrid model (HM) was developed that utilized the mechanistic processes of WRF-Chem and observed levels of PM_2.5, CO and NO₂. The HM performed adequately at multiple sites in Delhi (r = 0.19–0.47) and Kanpur (r = 0.38–0.43). The contribution of CRB to PM_2.5 was at 31 ± 16% (in 232 ± 36 μg/m³) in Delhi and 21 ± 15% (in 233 ± 38 μg/m³) in Kanpur. The contribution of SOA in CRB-contributed PM_2.5 was 18 ± 9% (Delhi) and 29 ± 21% (Kanpur).

在印度北部（约 30,000 km ²区域），10 月至 11 月的几个月见证了作物残茬燃烧 (CRB)。本研究旨在评估 CRB 排放对远离源头的PM _2.5和二次气溶胶 (SA) 的影响。化学传输模型 WRF-Chem（具有化学机制，RADM2 和 MADE/SORGAM）应用于 840 × 840 km ²（以德里为中心）的域，输入 EDGAR-HTAP 的人为排放源和火灾清单美国国家大气研究中心。同时，在德里和坎普尔对 PM _2.5及其成分、CO 和 NO ₂进行了测量。该模型低估了 PM _2.5并显示出较差的预测 (r  < 0.15)，二次有机气溶胶 (SOA) 的形成微不足道（在 PM _{2.5 中}< 1% ）。为了改进模型，开发了一个基于线性回归的混合模型 (HM)，该模型利用 WRF-Chem 的机械过程并观察到 ​​PM _2.5、CO 和 NO _{2 的水平}。HM 在德里 ( r  = 0.19–0.47) 和坎普尔 ( r  = 0.38–0.43) 的多个地点表现良好。CRB 对 PM _2.5的贡献在德里为 31 ± 16%（在 232 ± 36 μg/m ^{3 中}），在坎普尔为21 ± 15%（在 233 ± 38 μg/m ^{3 中}）。SOA 在 CRB 贡献的 PM _2.5中的贡献为 18 ± 9%（德里）和 29 ± 21%（坎普尔）。