Quantifying the impact of biomass burning and dust storm activities on aerosol characteristics over the Indo-Gangetic Basin

The high aerosol loading over the entire Indo-Gangetic Basin (IGB) region in the northern India attracted attentions of scientific community especially when about 900 million people living in the areas suffered with poor air quality due to intense fog, haze and smog during the post-monsoon/winter period and dust storm activity during the summer period. The present study focused on first long-term comparative study to quantify the aerosol characteristics during the biomass burning (October-November) and dusty (April-June) periods using satellite measurements from 2004-2018 at three different locations: Jaipur, Kanpur and Ballia over IGB. The highest aerosol optical depth (AOD) values for the biomass (0.74 & PLUSMN; 0.35) and dusty period (0.63 & PLUSMN; 0.34) were observed at Kanpur during the entire study period. The finer particles were found to be dominant during the biomass period at all the locations. During the biomass burning period, an increased AOD trend was observed at Ballia (0.017 year(-1)), followed by Kanpur (0.0144 year (-1)) and Jaipur (0.0061 year(-1)) whereas during the dusty period, an increasing trend was observed at Ballia (0.0074 year(-1)) and decreasing trend over Jaipur (-0.0132 year(-1)) and Kanpur (-0.0083 year(-1)). During the biomass burning period, anthropogenic aerosol (AA) types were found to be dominant over Kanpur (52%) and Ballia (56%) while clean condition (CC) aerosol type was dominant over Jaipur (69%). On the other hand, during dusty period, the highest contribution of desert dust (DD) was observed at Kanpur (37%) and Ballia (30%); however, CC type of aerosol dominated over Jaipur (42%). The potential source sectors and the transport pathways of pollutants have been widely characterized at all the stations using the potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analyses with the backward air mass trajectories. Results revealed that the high levels of aerosol over the stations are mainly from the local areas and also from the upper and middle IGB region.