Impact of urban expansion on regional temperature change in the Yangtze River Delta
长江三角洲城市带扩展对区域温度变化的影响

Based on non-radiance-calibrated DMSP/OLS nighttime light imagery from 1992 to 2003, urban land area statistical data, meteorological data and land surface temperature data retrieved by MODIS and NOAA/AVHRR data, the influence of urbanization on regional climatic trend of temperature in the Yangtze River Delta (YRD) was analyzed. Conclusions are as follows: 1) There is a significant urbanization process from 1992 to 2003 in the YRD. Four city clusters of Nanjing-Zhenjiang-Yangzhou, Suzhou-Wuxi-Changzhou, Shanghai and Hangzhou Bay form a zigzag city belt. The increase rate of annual mean air temperature in city-belt is 0.28–0.44°C/10a from 1991 to 2005, which is far larger than that of non-city-belt. 2) The urban heat island (UHI) effect on regional mean air temperature in different seasons is summer>autumn>spring>winter. 3) The UHI intensity and the urban total population logarithm are creditably correlated. 4) The UHI effect made the regional annual mean air temperature increased 0.072°C from 1961 to 2005, of which 0.047°C from 1991 to 2005, and the annual maximum air temperature increased 0.162°C, of which 0.083°C from 1991 to 2005. All these indicating that the urban expansion in the YRD from 1991 to 2005 may be regarded as a serious climate signal. Foundation: Concentrated fund item of national science and technology foundation work, No.2005DKA31700-06-20; Jiangsu Natural Science Foundation, No.BK2005163; Climate change special foundation of China Meteorological Administration, No.CCSF2006-32 Author: Du Yin (1978–), Ph.D Candidate, specialized in climatic changes.