Abstract: A scientific-based understanding of temporal and spatial patterns and driving factors of urban surface thermal fields is an important prerequisite for the upgrading of urban ecosystems. Kashgar City, the throat hub of civilization and transportation between the East and the West, features heavily in the Belt and Road initiative. Landsat series of remote-sensing images in 1998, 2008, and 2018 of Kashgar on the western edge of the Tarim Basin were adopted in this study. The land surface temperature (LST) was retrieved with the radiative transfer equation algorithm and the spatial variation of surface temperature in Kashgar City was analyzed through transfer matrix with the help of GIS and RS technology. On the basis of extracting impervious surface index (IBI) and vegetation coverage (FVC), 6 types of influencing factors including altitude, slope, population density, IBI, FVC and land use type were integrated to detect the spatial heterogeneity and driving factors of the surface thermal field with geographic detectors in Kashgar City in the past 20 years. The results show that: The medium temperature and the higher temperature areas were contiguously distributed in the urban built-up area, the low temperature and lower temperature areas were inlaid in the periphery of the built area in dots, and the high temperature and extremely high temperature areas were distributed in patches in the north of the urban area. With the rapid development of the region, the medium temperature area has gradually dominated the whole area. In 2018, the area of the medium temperature zone was 161.89 km², but due to the coexistence of cropland invasion, urbanization and forestation, the area of low temperature zone increased by 4.58% with bare lands effectively improved, and the area of the high temperature and ultra-high temperature zone saw a drop of 20.41 km². The spatial differentiation of the surface thermal environment in Kashgar is the result of multiple factors. IBI represents the core factor affecting the spatial differentiation of LST with the contribution rates of 1998, 2008 and 2018 to be 87.8%, 74.6%, and 80.8%, respectively, and the multi-factor interaction is obvious. The interactive explanatory powers of IBI and land use types in 1998, 2008 and 2018 were 0.912, 0.746, and 0.873, respectively. The research results can provide reference for urban ecological protection and sustainable regional development in Kashgar City.

Key words: land surface temperature, geographical detector, conversion matrix, Kashgar City