Abstract:

The spatial and temporal variation of urban heat island in summer in Chengdu have been analyzed by using MODIS land surface temperature and DMSP/OLS nighttime light imagery data. The results showed that along with the urbanization process, great changes have taken place in the thermal environment. The temperature field transferred each other and the medium temperature was mainly replaced by the sub-high temperature in the whole area. The urban heat island has a large diurnal variation, the heat island area is increasing during summer daytime in Chengdu, resulting in Chengdu and its surrounding satellite towns integral heat island become a major heat island area. The contribution to regional warming of the urban heat island in 2000 and 2010 were 0.13℃ and 0.29℃ respectively, and the variation reaches 0.16℃. However, there is no existing of a large area of strong heat island in night. Since 2000, the size of the urban heat island in the old city area showed an increasing trend, but the change is not obvious. The scale of urban expansion district heat island had significantly increased, the newly enhanced heat island area reached 166.43 km² and changed in 54% in 2010 comparing with 2000. The decrease of daily temperature range in Chengdu which has a relatively high level of urbanization is completely attributable to the urbanization effect, indicating that changes in surface temperature and urbanization are closely related. The urban heat island and the square root of the population have a good positive correlation. In the non-agricultural population of Chengdu, every increase of 1 million persons is linked to an increase of 0.4℃ of the heat island intensity.

Key words: urbanization process, urban heat island, MODIS, DMSP/OLS