Urban Heat Island Effect Change Research Based On Multi-indexes In Changsha

In this Thesis we can used city center and surrounding towns of Changsha as research areas,with RS & GIS technology and Landsat TM/ETM+ images as the data sources. Arcgis and ENVI software were used to land surface temperature(LST) inversion and remote sensing index calculation, SPSS were used to analyze the data, and analyzed the relationship between remote sensing index and urban heat island effect,Through this research not only comprehensive analysed of index factor about urban heat island effect in Changsha,but also provide a reference for the construction of two-oriented society and city planning.The main content of this paper include:(1) Based on the remote sensing data in 2003,used four single channel algorithms for LST inversion,Choosed best method for LST inversion in different time.(2) Used Qin’s mono-window algorithm on different time remote sensing image in study area for LST inversion,and compared the results with the actual measurement temperature. Graded LST retrieval results,contrasted analysis of changes in the surface temperature of the three years.(3) ENVI software were used to calculate NDVI (normalized difference vegetation index), NDBI (normalized difference built-up index), MNDWI (modified normalized difference water index), NDISI (normalized difference impervious surface index), and analysis their changes.(4) Correlation analysis was carried out on LST and the remote sensing index,discussed the relationship between remote sensing index and the urban heat island effect change.Through the contrast of LST inversion methods found that Qin’s mono-window algorithm have high inversion accuracy and strong parameter sensitivity,it can be used as the research method of this paper.The result shows surface temperature distribution are quite different of year 1991,2003 and 2015.By dividing the surface temperature rating,statistics heat island area about high-temperature and very high-temperature region are 457.2126km2,506.2815km2 and 483.9255km2,accounting for 11.83%,13.08%,12.50%. From the spatial distribution, the urban heat island distribution is relatively scattered except for the area of Xiangjiang in 1991. In 2015, mainly concentrated in the Changsha municipal districts and Xingsha, Huanghua airport,Gao Tangling, etc.Through calculated remote sensing index of study area and research the relationship between LST and remote sensing index found that water for Changsha municipal districts have great cooling effect,but with the urban area expanded reduced. Vegetation cooling effect in municipal districts is not obvious,with the expanding of city, the cooling effect of vegetation is more and more strong. While buildings and impervious surface has been the main factors of the surface temperature increase.Four indexes correlation with the surface temperature changes from high to low in turn is NDISI, NDBI, MNDWI and NDVI. The establishment of the comprehensive index can accurately distinguish the distribution of the urban heat island and non heat island region. The results showed that the urban heat island area in the study area increased by 440.6382km2 in recent 25 years, the growth rate was 135.81%.