Abstract:

 Urbanization process has outstanding influence on the climate change Its very important to analyze the urbanization process comprehensively and accurately The researches in the past often use single index method such as population to represent the process of urbanization But urbanization is a comprehensive process which can reflect the level of regional economic，social and culture developmentIn this paper，a new method was used to calculate the urbanization comprehensive evaluation index，and the relationship between urbanization process and urban heat island was discussedTaken Nanjing as an example，four outstanding urbanization index data from 1985 to 2010 had been selected，including urban population，power consumption，civil car ownership and waste gas emissions Based on the backpropaqation （BP） artificial neural networks，the weight of each index was calculated. Combined with aggregative indicator method，the urbanization comprehensive evaluation index presenting the comprehensive urbanization level was built，and the heat island effect in Nanjing was analyzed by anual average temperature (1985-2007) Meanwhile，in order to discuss the relationship between urbanization process and urban heat island，correlation analysis was conductedThe results show as follows. （1）The weights of evaluation index by BP artificial neural network were all large，especially the civil car ownership reached 2919%It indicated that population，energy，environment and other aspects of urbanization process were of great significance to the urban development level evaluationThus，single index method is not accurate（2） The new method in this paper could present the urbanization prcess betterThe urbanization comprehensive evaluation index had a good perform to present the urbanization process of NanjingIt was divided into two stages in Nanjing One was stable development stage （1985-2000） and another was rapid development stage （2001-2010） The growth rate of urbanization comprehensive evaluation index was 01/10a and 06/10a， respectivelyIn addition，the effect due to rapid development was different from slow development（3）The mean annual temperature showed a fluctuated increase and had sharp distinction between urban and suburban temperature The mean distinction was 03℃The heat island intensity appeared rising trend The growth trend presented obviously，especially after 2000 by 019℃/10a （4）The correlation between heat island intensity and urbanization comprehensive index was remarkable The correlation coefficient was 075 and was significantly related at confidence level of 005Each single index had high correlation to the heat island intensityAmong them，civil car ownership was of the largest correlationIt indicated that the urbanization had great effect on the surface warming，especially in the automobile exhaust，industrial waste gas emissions and energy consumptions