Long-Range Transport of Aerosols and Regional Sources Using MODIS and NASA MERRA Reanalysis Over South Asia

Abstract

The increasing atmospheric aerosol loading and their related effects on health, weather/climate, cloud microphysics, and the local/regional circulation patterns over the South Asian region are well recognized. However, a composite view of the sources of aerosols that directly link to the aforementioned aerosol�s effects is limited. In addition, the understanding of how well the aerosols are transported for long distances in various models is also limited. This study uses the modified conventional Concentration Weighted Trajectory method over an extended domain over the Indian region to elucidate major aerosol sources for the Indian domain using the aerosol datasets from satellite (Moderate Resolution Imaging Spectroradiometer: MODIS-Terra) and reanalysis (Modern-Era Retrospective analysis for Research and Applications, Version-2: MERRA-2) datasets. It is found that the major aerosol source regions such as the Northwest regions of India, North Arabian Sea, Indo-Gangetic Plains, Arabian Peninsula, Northeast of India, and central India are captured well with varying spatial strength and seasonality. The Arabian Sea and Northeast India are the important virtual sources of aerosols where a significant accumulation of aerosols happens and are later transported to regions over India. The fidelity of the method is qualitatively evaluated using natural mineral dust and sea-salt aerosols (whose source locations are reasonably known) simulated by MERRA-2. Based on spatial pattern and seasonality, it appears that MERRA-2 simulation of dust aerosols is low biased in relation to MODIS-Terra indicating limitations in model physics and hence reflected in the long-range transport of aerosols. Analysis using methods such as these by synergistically linking satellite observations, air mass trajectories, and model simulations of aerosol species will allow an understanding of model capability/limitations in the long-range transport of aerosols allowing future improvements in aerosol modeling and impact studies. � King Abdulaziz University and Springer Nature Switzerland AG 2024.