Spatial-temporal characteristics of the urban heat island effect in Xiamen, China

Applying air temperature at 2-m data observed actually from automatic weather stations from September 2017 to August 2019 and the long-term air temperature data from 1960 to 2019, we analyzed the spatial and temporal characteristics of the urban heat island intensity (UHII) in Xiamen city and urbanization effect on the trends of the air temperature at two urban stations. The results showed that the high-value areas of the UHII were primarily distributed in south of central to northern parts of the urban area, with UHIIs >0.60 °C. Affected by the sea breeze, the UHII center tended to be inland during the daytime and on the coast and islands at night. The UHII during the daytime was greater than at nighttime, and the amplitude of the diurnal variation in the mainland urban areas was greater than that on the Xiamen Island. Seasonally, the UHII during spring and summer was typically higher than that of autumn and winter. The two long-sequence urban observational stations at Xiamen and Tongan have recorded obvious enhancement process of the UHII around the observational sites during the past 60 years, with the trend of the annual mean UHII at Xiamen station reaching 0.13 °C/10 yr, which has contributed 38.8% to the overall warming near the station.