Evaluation of PM2.5 Surface Concentrations Simulated by NASA’s MERRA Version 2 Aerosol Reanalysis over the Tibet Plateau

Abstract:

The Tibetan Plateau and its surroundings are known as the Third Pole (TP), which is surrounded by Asian dust and strong anthropogenic emissions. This region is noted for its high rates of glacier melt and the associated hydrological shifts that affect water supplies in Asia. Although the TP region has fewer human activities, pollutants from the adjacent surrounding can be transported into the plateau through long distances under the action of atmospheric circulation, and they are showing a continuous strengthening trend. It can really affect the TP region’s vulnerable environments. The PM2.5 (particulate matter with a diameter ≤ 2.5 µm), an essential component of air pollution, is closely linked to adverse effects on human health. However, limited surface measurement and the lack of monitoring with adequate spatial resolution hamper studies related to air pollution and its impact on various societally relevant issues, especially in unique alpine areas where it is not easy to make observations. The National Aeronautics and Space Administration (NASA)’s Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) has begun estimating the global distribution of PM2.5 mass concentrations at high spatio-temporal resolutions. This study assesses MERRA-2’s PM2.5 results by comparing them with ground-based measurements conducted at 4 stations across the TP region between 2011 and 2013. The comparison of MERRA-2 aerosol species to the observations is also performed. Our analysis shows that MERRA-2 generally overestimates the PM2.5 concentration.