The NSTM is the most developed region in Xinjiang in terms of economy, education, science, and technology, as well as an essential hub of the Silk Road Economic Belt to Central Asia and Europe (Development and Reform Commission of Xinjiang Uygur Autonomous Region 2017 ). The region is distributed in the arid and semi-arid climate zone, a typical temperate continental climate with scarce precipitation, intense evaporation, dusty weather, and large annual and daily temperature differences (Liu et al. 2018 (link)). The Taklamakan Desert, China’s largest desert, and the Gurbantunggut Desert, China’s second-largest desert, respectively, border the northern and southern slopes of the Tianshan Mountains, together with rapid urbanization in recent years, has led to serious urban and regional air pollution problems (Han 2018 (link)). Ten cities in the study area, from Hami in the east to Ili Kazakh in the west, are shown in Fig. 1 along with their locations and elevations. Table S1 provides more details on these cities, including longitude, latitude, elevation, population, GDP, and car parc.

Location of the study area. The DEM data (Shuttle Radar Topography Mission, SRTM) were downloaded from the Geospatial Data Cloud (http://www.gscloud.cn/) and processed using ArcGIS 10.2 software. a Map of China and location map of the Xinjiang deserts provided by National Tibetan Plateau Data Center (http://data.tpdc.ac.cn): I. Taklimakan Desert, II. Gurbantunggut Desert. b Enlarged topographic map of NSTM