| Since the reform and opening up,China’s economy has grown rapidly,and the process of urbanization is accelerating.The rapid development of urbanization has brought about economic growth and cultural prosperity in China,but it has also caused a series of problems in the deterioration of the ecological environment.The rapid expansion of the city has led to the replacement of natural vegetation such as ground vegetation,water,and land by buildings,roads,and artificial landscapes.This has resulted in tremendous changes in the underlying structure of the city,which will eventually lead to higher temperatures in the city center than in the surrounding suburbs.This is the "urban heat island" The generation of "urban heat island" has caused great impact on the sustainable development of cities and people’s quality of life.In order to effectively understand the production mechanism,monitoring methods and prevention methods of urban heat islands,we need to conduct corresponding research on urban heat island.In this paper,with the help of GIS and RS,Landsat5TM and Landsat 8 OLI/TIRS data are used as data sources,combined with the improved universal single-channel method the surface temperature of time series remote sensing image of the study area is retrieved.Based on the result,we revealed the temporal and spatial variability of the thermal environment in Xiamen on an interannual and seasonal scale,and quantitatively analyzed the thermal landscape changes in the whole and various regions of Xiamen.The important research results of the paper as follows:(1)"Urban heat islands" is greatly influenced by the underlying surface of the City.According to the data of Xiamen thermal profile,we can see that the different underlying surface structure will lead to large differences in land surface temperature.Artificial buildings such as buildings and roads and large areas of bare soil or fallow land have higher temperatures.Water,greenbelts,and vegetation have a good cooling effect.(2)During the study period,standard deviation and average temperature of’ the normalized surface temperature in the two seasons of summer and winter in Xiamen showed a tendency of fluctuation and decline.Among them,the average temperature in the first 10 years of summer decreased by 3.87%,the average annual growth rate in the last 3 years was 21.16%,the standard deviation between 13 years decreased by 0.0279,and the average winter surface temperature decreased by 0.0074 between 13 years and the standard deviation decreased by 0.0122.In general,the surface temperature fluctuations in Xiamen are getting smaller and smaller,the temperature is relatively stable,and the temperature difference is reduced.(3)During the study period,the temperature rising and cooling areas in the study area in summer accounted for 49.97%and 50.03%,respectively,and in winter accounted for 1 7.21%and 82.79%respectively.The changes of temperature in summer and winter show a certain spatial distribution difference.The distribution of surface temperature and urban development are basically the same,and the center of warming area shifts from coastal to inland areas.(4)The surface thermal landscape index showed that the indicators of thermal patch in Xiamen basically showed a trend of improvement.In terms of patch type index,the NP and PD in summer and winter were reduced by 75,0.0384,1140,and 0.5834,respectively,indicating that the landscape fragmentation was improved;the PAFRAC in summer and winter decreased by 0.0184 and 0.0076,respectively,indicating that the complexity of landscape shape was reduced.From the perspective of landscape types,the CONTAG indices for summer and winter have a decrease of 0.0384 and 0.5834,respectively,indicating that the connectivity between landscape types has decreased;both SHDI and SHEI have a decrease of 0.0053,0.0443,0.0033,and 0.0276 in summer and winter respectively.The increase shows that the distribution of various landscapes in summer and winter has improved.(5)The total area of mutual transformation between thermal and non-thermal patch areas is basically the same.In winter,the area mainly transformed from non-thermal zone to thermal zone,and the conversion area of non-thermal zone to thermal zone is increasing. |
