The Contribution of Local Anthropogenic Emissions to Air Pollutants in Lhasa on the Tibetan Plateau

The Tibetan Plateau (TP), a region with limited human activity, is sensitive to regional and global climate change. In recent decades, surface observations have shown that concentrations of air pollutants (CO, NO2, SO2, and PM2.5) in Lhasa, a city on the TP, are similar to those in regions with high anthropogenic emissions (e.g., Eastern China). This study utilized the WRF-Chem model and observational datasets to evaluate the concentrations and sources of air pollutants in Lhasa during August 2016. Our results show that the WRF-Chem model with the standard emission inventory underestimated the surface concentrations of CO, SO2, and PM2.5 in Lhasa from 3 August 2016, 0:00 to 15 August 2016, 23:00 (UTC +8) by 59%, 92%, and 79%, respectively. Sensitivity simulations show that the contribution of long-range transport of air pollutants from Eastern China and India is less than 10% for Lhasa. Insufficient emissions are found to be the main reason for the model's underestimation of air pollutants in Lhasa. Our study suggests that the emissions of CO, SO2, and PM2.5 in Lhasa in August 2016 might be underestimated by 85%, 93%, and 88%, respectively. Local anthropogenic emissions have a significant impact on urban air quality on the TP and deserve further attention.