The Effect Of Urbanization On Regional Temperature Change In Yangtze River Delta,China

Regional climate was influenced both by global climate change and local urbanization.How to quantify the respective contribution of global climate change and urbanization effects on regional climate is very important.In the paper,twenty-five years air temperature data from twenty ordinary weather stations in Yangtze River Delta region(YRD)from 1988 to 2013,six time-series of land use land cover data in every five years derived from high resolution imageries of Landsat from 1990 to 2015 and demographic cencus data from 1988 to 2013 were used to quantify the contribution of urbanization impact and global climate change on regional climate and further to explore the spatio-temporal pattern of urbanization warming effect.The results are as follows:1.The air temperature in YRD tended to be warmer in the past twenty-five years and the average increasing rate of annual mean temperature is 0.505?/10a.Global climate change and local urbanization both contributed to the regional warming,and accounted for 77.6%and 22.4%to the warming,respectively.2.The impact of urbanization on regional air temperature showed spatio-temporal differences.The regional warming effect synchronized temporally and spatially with the urbanization processes.The urbanization warming effect in the period of 2000 to 2013 is greater than that in the period of 1988 to 1999.Year 2000 was detected as the turning point from which marked air temperature increase was identified.The time of the turning point was well consistent with the initiation of the rapid urbanization process in YRD in 2000.The area with larger warming effect were spatially matched with the Z-shaped urbanization belt of the cities in YRD region.3.The warming effect attributable to urbanization increased with the amount of the area of urban landuse.Binomial relationship existed between the increasing rate of air temperature and the increasing rate of urban landuse at station scale,but a logarithmic relationship at country scale.Linear relationship was also found between the urban population and the regional air temperature increase,every incretment of one million urban population will result in 0.0095 ? increase in annual mean temperature in YRD region.4.The amplitude of the urbanization warming effect depended not only on the speed of urban landuse increase,but also on the size of existed urban area.The warming rate of the air temperature of the highly-and intermediate-developed cities were significantly larger than those of the lower developed cities.