Multiscale spatiotemporal variations of NOx emissions from heavy duty diesel trucks in the Beijing-Tianjin-Hebei region

Heavy-duty diesel trucks (HDDTs) cause serious pollution to urban and regional environment. Understanding the spa-tiotemporal pattern of pollution emissions and its impact factors is the basis for implementing emission reduction mea-sures. However, since the multiscale emission inventory of HDDTs is not currently established, multiscale analysis of these issues is still lacking. Therefore, this study uses massive trajectory data, detailed vehicle specification information and road network information, combined with localized emission factors, to construct a multiscale NOx emission in-ventory of HDDTs with high spatiotemporal resolution in the Beijing-Tianjin-Hebei region. Then the multiscale spatio-temporal variations of NOx emissions are analyzed by using spatial statistical indicators and multiscale geographical weighted regression model. The results show that the NOx emissions of HDDTs show different spatiotemporal distribu-tion and aggregation characteristics at different scales. Specifically, link-scale emissions are concentrated to a few high-ways and are dominated by Low-Low cluster. While county-scale and city-scale emissions are concentrated in the eastern plains, mainly in High-High and Low-Low clusters. There are spatial heterogeneity and multiscale effects of so-cioeconomic and road attribute characteristics on the NOx emissions from HDDTs. Population density, urbanization rate, proportion of second industry, and proportion of highway affect the NOx emissions of HDDTs globally, while per capita GDP and road density have local effects. Our results extend the scientific understanding of the multiscale spatiotemporal variations of HDDTs and may provide a scientific basis for the development of targeted emission con-trol measures for HDDTs.