Post‐Monsoon Pollution Events in the Indo‐Gangetic Plain Using 18 Years [2007–2024] of IASI Carbon Monoxide Satellite Measurements

Abstract In recent years, the Indo‐Gangetic Plain (IGP) has experienced recurring intense air pollution episodes during the post‐monsoon season (October–November), posing significant health risks to millions of inhabitants. These pollution events coincide with agricultural waste burning, emitting large quantities of carbon monoxide (CO) into the troposphere. Using 18 years of Infrared Atmospheric Sounding Interferometer (IASI) measurements from the Metop satellites, we examined the interannual variability of CO concentrations over the IGP during the post‐monsoon season from 2007 to 2024. We focused on three representative years with varying CO levels (2011, 2017, and 2024) to determine whether CO pollution events in the IGP were more influenced by fire intensity, represented by the Fire Radiative Power (FRP) from the Moderate Resolution Imaging Spectroradiometers, or by meteorological parameters, particularly average winds in the 0–2 km layer, provided by ERA5 reanalysis. The comparison of wind patterns and FRP showed that surface winds primarily drive CO pollution severity. Extreme CO concentrations were found in 2017 and 2024 which coincided with prolonged periods of weak surface winds. In contrast, 2011 exhibited moderate CO concentrations throughout the post‐monsoon season due to stronger winds, despite higher FRP. Our findings highlight the influence of surface winds in conditioning extreme post‐monsoon pollution episodes in the IGP and demonstrate the ability of IASI for long‐term monitoring of regional air pollution caused by agricultural waste burning. However, these results rely on the accurate detection of fire activity, which remains challenging due to limitations in satellite observations and changes in agricultural practices.