Assessment of spatio-temporal variation in AOD over four coal mine sites of Assam through satellite observation

Aerosol optical depth (AOD), an important parameter for ecological studies, is paramount when assessing modifications in climate patterns. To evolve a regional aerosol representation of four varied coalfields across Assam, sixteen years (2003–2019) of aerosol variability and trends in aerosol loading through spectral AOD using MODIS-Terra (Moderate Resolution Imaging Spectroradiometer) was interpreted. Assam is part of the Indo-Gangetic Plain (IGP), India, and can be considered a key hotspot for the continuous contribution of aerosols. This first-of-its-kind study analyzed the long-term spatio-temporal variations in AOD in Assam’s coal mines by combining it with the long-term satellite observations from MODIS. The Assam region revealed a varied and distinct spatio-temporal variability in aerosol distribution. For the annual average AOD in coal mines, Assam varied from 0.61 to 0.35, where Singrimari reported the highest mean AOD, indicating it is home to the state’s high-polluting coal mines, whereas Sheelveta reported the lowest AOD value. Seasonal variation was additionally extrapolated, with minimum AOD during post-monsoon and monsoon and maximum AOD during summers and winter months. Moreover, a statistically significant increasing trend in the aerosol concentration was noticed in all four regions, namely, Singrimari (27.29%), Sheelveta (14.59%), Dilli-Jeypore (11.58%), and Mikir (16.27%). This study is significant since it evaluates the air pollution produced over mines, as well as the degree of aerosol concentration produced. The study also suggests effective strategies for decreasing mining-induced air pollution. The findings of this study support future climate projections and provides baseline data for policymakers and model simulation for climate change analysis.