Impacts of land-cover types on an urban heat island in Hangzhou,China

This research examined the impact of urban land-cover types on the urban heat island (UHI) in Hangzhou, China. Air temperatures (T_air) measured at a height of 1.5 m at times 00:00, 10:00, 14:00, and 18:00 were used for atmospheric urban heat island (AUHI) analysis. Data from the Environmental and Disaster Monitoring and Forecasting Satellite B (HJ-1B) were utilized to retrieve land surface temperature (LST) for surface urban heat island (SUHI) analysis and to map land-cover distribution. Pearson correlation and partial correlation analyses were performed to investigate the impacts of land-cover types on T_air, LST, and the relationship between T_air and LST. The results show that (1) LST and night-time T_air are sensitive to the amount of impervious surface and vegetation and (2) land-cover types did not significantly influence the correlation between LST and T_air at 10:00, but the amount of impervious surface and vegetation had significant impact at 0:00. This research indicates that the percentage of impervious surface is a good indicator for LST and night-time T_air, and for relating night-time AUHI to satellite-based observations of SUHI. This research also proposed a new method that considers both temperature patterns and land-cover types to explain the spatial variations in AUHI and a new indicator – cooling-distance rate – to help people to select a suitable living place when both work–home distance and work–home temperature difference are factors that they wish to consider.