Investigation of PM mass concentration over India using a regional climate model.

Seasonal variation of PM (Particulate Matter <2.5 μm) mass concentration simulated from WRF-Chem (Weather Research and Forecasting coupled with Chemistry) over Indian sub-continent are studied. The simulated PM are also compared with the observations during winter, pre-monsoon, monsoon and post-monsoon seasons of 2008. Higher value of simulated PM is observed during winter followed by post-monsoon, while lower values are found during monsoon. Indo-Gangetic Basin (IGB) exhibits high amount of PM (60- 200 μg m) throughout the year. The percentage differences between model simulated and observed PM are found higher (40- 60%) during winter, while lower (< 30%) during pre-monsoon and monsoon over most of the study locations. The weighted correlation coefficient between model simulated and observed PM is 0.81 at the significance of 98%. Associated RMSE (Root Mean Square Error) is 0.91 μg m. Large variability in vertically distributed PM are also found during pre-monsoon and monsoon. The study reveals that, model is able to capture the variabilities in spatial, seasonal and vertical distributions of PM over Indian region, however significant bias is observed in the model. PM mass concentrations are highest over West Bengal (82± 33 μg m) and the lowest in Jammu & Kashmir (14± 11 μg m). Annual mean of simulated PM mass over the Indian region is found to be 35± 9 μg m. Higher values of PM are found over the states, where the reported respiratory disorders are high. WRF-Chem simulated PM mass concentration gives a clear perspective of seasonal and spatial distribution of fine aerosols over the Indian region. The outcomes of the study have significant impacts on environment, human health and climate.