Remote-sensing evaluation of the relationship between urban heat islands and urban biophysical descriptors in Jinan, China

Global warming and climate change have gained more and more attention because the global mean surface temperature has increased since the late 19th century. With the progress of rapid urbanization, Jinan city has witnessed a significant urban thermal environment change. To investigate the relationship between urban heat islands and urban biophysical descriptors, the city’s biophysical properties along with land surface temperature (LST) in 1992 and 2011 were retrieved from the Landsat TM images. Additionally, three thematic indices were employed to extract the features of the impervious surface, water, and vegetation, respectively. The correlation and spatial overlay of these land surface features were then analyzed. The results show that the Jinan region has witnessed very fast urban sprawl. The total impervious surface area of the region in 2011 was 134.7% more than that in 1992. This increase significantly reduced the vegetation and open water coverage in the urban area. Simultaneously, the expansion of impervious surfaces was accompanied by an increased urban heat island (UHI) ratio index, which increased from 0.43 in 1992 to 0.55 in 2011, showing that the UHI in Jinan has developed from a weak level to a significant level over the 19-year period. The quantitative analysis between LST and indices revealed that impervious surfaces have a positive exponential relationship with LST, while the water and vegetation are both negatively correlated with temperature. A multifactor analysis also indicated that the contribution of impervious surfaces to the LST could equal or even exceed that of the sum of vegetation and water.