Spatial heterogeneity of driving factors-induced impacts for global long-term surface urban heat island

A series of empirical analytical tools have been adopted to investigate the driving mechanisms of surface urban heat islands (SUHI) on a global scale, among which spatial heterogeneity is yet to be fully elucidated. In this study, we investigated the spatial non-stationarity of the driving factors concerning surface properties, climate conditions, and urbanization processes for global long-term SUHI. First, the potential impact on SUHI was explored using global ordinary least squares regression. Geographically weighted regression (GWR) and multi-scale GWR (MGWR) from local perspectives were employed for comparison. The results show that the MGWR has the highest goodness of fit at 0.87, 0.73, 0.90, 0.74, 0.85, and 0.76 for annual day/night (AD/AN), summer day/night (SD/SN), and winter day/night (WD/WN) scales, respectively. Although both global and local schemes exhibit similar influencing magnitudes and signs on the SUHI, the MGWR is better at capturing spatial non-stationarity. Globally, for AD, AN, SD, SN, WD, and WN, the coefficients of the urban-rural vegetation index difference (Delta EVI) and surface albedo difference (Delta WSA), urban mean precipitation (MAP), wind speed (WS), population density (PD), and urban area (UA) are -0.50, +0.30, +0.16, +1.31, -0.03, and +0.03, respectively, at daytime, and -0.38, -0.33, -0.39, -0.10, +0.18, and +0.08, respectively, at night-time. Given the spatial heterogeneity of multiple factors, Delta EVI exhibits a strong mitigation effect on the SD SUHI especially in arid zones. The negative influence of Delta WSA on night-time SUHI demonstrates a strong latitudinal disparity and greater sensitivity in the equatorial zone. The positive correlations between MAP and AD/SD SUHIs have evident latitudinal and longitudinal variations. The mitigation effect of WS displayed distinct coastal amplification, especially in WD. In contrast, the PD and UA presented prominent positive impacts on night-time SUHI with less seasonal contrast.