2013年专四作文真题附范文:节约花钱

under the background of serious urban heat island phenomenon, the water cool island effect of Changsha is studied in order to find some effective solutions to alleviate the urban high temperature. In this paper, we select 50 water bodies in the main built-up area of Changsha and its surrounding area, and four Landsat8 remote sensing data which represent four seasons of spring, summer, autumn and winter are used to analyze the seasonal variations of the water cooling island effect of Changsha through a number of methods which include surface temperature inversion, correlation analysis and stepwise variable selection. Furthermore, the significant influencing factors of the water cool island effect in Changsha under different seasons can be identified.The final results are as follows: (1) the water cool island effect of Changsha changes significantly with the season. The cool island intensity of water is the largest in summer, followed by spring and autumn, and the smallest in winter. (2)the better cooling effect can be achieved by increasing the vegetation cover within 1,000 meters and reducing the building cover within 900 meters of water bodys. (3)the land use around water bodys are the main factor that affect the cool island effect in any season, and the size of the water area is the main factor that affects the cool island effect in spring, summer and autumn, but elevation and the shape index of water bodys are not the main factors that affect the water cool island effect in any season.