The present study reports daily, monthly, and seasonal variations of aerosol optical depth (AOD) using aerosol robotic network (AERONET), MICROTOPS-II Sunphotometer, and Moderate Resolution Imaging Spectroradiometer (MODIS) data over three most polluted cities such as Kanpur, Varanasi, and Jaipur in the Indo-Gangetic Plain during 2011–2015. The monthly mean variations of AOD and Angstrom Exponent were also presented and compared with the meteorological parameters for all three cities. The concentrations of AODs in Kanpur and Varanasi were observed higher than in Jaipur throughout the study period. Overall maximum correlation (R² = 0.74) was found in between AERONET and MODIS AOD in the winter season over Kanpur during 2011–2015, whereas the lowest correlation (R² = 0.41) was found in between MICROTOPS-II Sunphotometer and MODIS AOD over Varanasi for the same period in the pre-monsoon season. Spectral variations of AODs at five different wavelengths, i.e., 380, 440, 500, 675, and 870 nm, were derived using AERONET for Jaipur and Kanpur and using MICROTOPS-II Sunphotometer for Varanasi during 2011–2015 inferred clearly that increasing wavelength provides decreasing AODs. The Hybrid Single-Particle Lagrangian Integrated Trajectories model was used for the backward trajectories analysis to assess the sources of large aerosol loadings over Jaipur, Kanpur, and Varanasi cities during some typical days.

本研究报告了在三个污染最严重的城市（如坎普尔，瓦拉纳西）使用气溶胶机器人网络（AERONET），MICROTOPS-II太阳光度计和中分辨率成像光谱仪（MODIS）数据得出的气溶胶光学深度（AOD）的每日，每月和季节性变化。 ，以及斋浦尔（Jaipur）在2011–2015年期间。还介绍了AOD和Angstrom指数的月平均变化，并将其与所有三个城市的气象参数进行了比较。在整个研究期间，坎普尔和瓦拉纳西的AOD浓度均高于斋浦尔。 在2011–2015年坎普尔冬季，AERONET和MODIS AOD之间的总体最大相关性（R ² = 0.74），而最低相关性（R ² 在季风前季节的同一时期，在瓦拉纳西的MICROTOPS-II日光光度计和MODIS AOD之间发现= 0.41）。使用AERONET对斋浦尔和坎普尔进行了分析，得出了在五个不同波长（即380、440、500、675和870 nm）处AOD的光谱变化，并在2011-2015年间使用了MICROTOPS-II太阳光度计对瓦拉纳西进行了推论，清楚地推断出增加的波长会降低波长AOD。使用混合单粒子拉格朗日综合轨迹模型进行后向轨迹分析，以评估斋浦尔，坎普尔和瓦拉纳西城市在某些典型日子中较大的气溶胶负荷来源。