Dynamic Monitoring and Evaluation on Urban Heat Island Effects Using Remote Sensing Technology

Land surface temperature (LST) of the Nanchong City in China was retrieved using Landsat TM/ETM+ images, which obtained on September 15, 1988, July 22, 2000, and September 20, 2007 respectively, and then be classified by Mean-standard Deviation method. The spatio-temporal evolution of UHI was analyzed including UHI distribution variation and transformation. Research result are the following: (1) The UHI area in the Nanchong city was continually increasing from 1988 to 2007, and the rate in the later period (from 2000 to 2007) was 1.8 times that in the previous period (from 1988 to 2000). The UHI expansion was synchronous with built-up area, and the expansion form was extending along and outwards the Jialing River. (2) The UHI-in area was far greater than the UHI-out area from 1988 to 2007. In the previous period, the UHI-into rate was 4.0 times that of UHI-out, and in the later period, the UHI-into rate was 2.2 times the UHI-out rate. Comparison of the previous and later period, the UHI-into rate or UHI-out rate was increasing, but the increased scope of UHI-into rate was more 22.42 hm2/a than UHI-out rate. In short, the UHI in the Nanchong City was continuously strengthening from 1988 to 2007, and the rate in the latter period was higher than that in the previous period.