Spatiotemporal changes of the urban heat island of a coastal city in the context of urbanisation

This study quantitatively analysed the spatiotemporal changes of the urban heat island (UHI) of Xiamen City in the context of urbanisation, using Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) thermal images acquired on similar dates in the winter of 1987, 1992, 1997, 2002 and 2007. UHI intensity and extent were used to quantify the changes, together with landscape metrics PLAND, PD, CA, NP, P-UHI, NP-UHI, PD-UHI, etc. The results show that the winter UHI of Xiamen has become more and more striking in the past 20 years in almost all the indices used. The UHI intensity increased to over 10 degrees C, and UHI extent and thermal patch number also increased remarkably. At the same time, UHI was more dominated and fragmented by high-grade thermal patches. In winter these UHI formed several hot spots and areas of significance, distributed along the coastline. This pattern was related to industrial zones and large infrastructure constructed in coastal areas during the rapid course of urbanisation, since both large impervious ground surfaces, large-sized and endothermic factory building roofs were the sources of these hot spots. A similar seasonal analysis was also carried out, which proved that autumn UHI was most intense in Xiamen and the change in season does not change the number of UHI areas of significance.