Estimation of Particulate Matter (PM_2.5) Over Kolkata

Particulate matter has a diverse range of effects on human health and climate due to which it has emerged as a key parameter in monitoring air quality. The current study explores and estimate the concentration of particulate matter (PM_2.5) from MODIS AOD product over the city of Kolkata for a period of 3 years (2019–2021). PM_2.5 concentration dataset was acquired from seven CPCB ground stations spread throughout Kolkata. Further, the study utilized the 1-km MODIS AOD product and meteorological parameters from MERRA-2. Considering the statistical analysis of data, four regression models were derived and considered for PM estimation. Daily estimated PM_2.5 concentrations were compared against respective observations. The developed models were evaluated with the help of statistical methods. Model-2 based on the multi-linear regression equation was found to be the best fit model having a strong positive correlation between the estimated and observed PM_2.5 values (R = 0.814). The root mean square error (RMSE) was estimated at 22.54 µg/m³. The estimated PM_2.5 values were able to capture the trend of PM_2.5 concentrations on the ground level. The normalized mean bias (NMB) value was − 0.315 and the mean absolute error was 18.94. The mean absolute percent error is estimated at around 5.16%. The results demonstrated that the developed model thus can be used to study the particulate matter concentration over areas where ground-based observation sites are sparse on the city level.