Seasonal Variation Of Urban Surface Thermal Environment Based On Landscape Pattern

Since 1980 s,with the developing of China's city rapidly,urbanization not only revealed in the area of tension,population growth,but also caused changes in local city climate.City heat island phenomenon is becoming increasingly serious,which brought great trouble to people's life.Urban heat island is an important reaction of urban ecological environment,which is caused by the change of land cover layer and the activity of human production and life.With the economic and social progress,the urban heat island is gradually serious,not only affects people's living environment,health,but also directly or indirectly brings a series of natural disasters.Urban heat island effect is not only affected by the type of land cover,but also affected by landscape pattern.Based on the remote sensing,geographic information systems,statistics,landscape ecology and other professional knowledge,this paper discusses the influence of land cover types on Urban Heat Island,and studies the seasonal changes of urban heat island effect.Changshu City,located in the Yangtze River Delta,China's rapid economic development,has a unique location advantage,compared with developed cities,is still in development.Taking Changshou City as the research object,this paper avoids the phenomenon of saturation of the big cities,in response to the call of the national development of urbanization economy.Changshu as the small cities' representative to study the thermal environment.According to the survey,Changshu City,still retain the characteristics of farming,according to the actual situation,Changshu City land use classified as dry land,paddy fields,woodlands,wetlands,water bodies,construction land.The seasonal variation of urban thermal environment in Changshu city was analyzed by selecting the data of HJ1 A / B in 2013 and the selected Landsat8 data.The main work is as follows:The land surface temperature is retrieved using the Landsat8 thermal infrared band,and the surface types are classified according to the environmental star data and the Google Earth data.The land surface temperature distribution map of the four seasons and the land use type map of the corresponding year were obtained.Based on the inversion results of the surface temperature,the heat island intensity band is divided to obtain the heat island intensity zonation map of four seasons,and the seasonal transfer of land use is analyzed.When the season transfer to autumn and winter,the proportion of the land transferred to the high heat island intensity zone is larger than that transferred to the low temperature zone,and the result is opposite when transfer to spring and summer.From the view of landscape pattern,patch area,shape index,average patch area,type area,maximum patch area,heterogeneity index and patch number were introduced.The results of temperature inversion and surface classification were superimposed,and the correlation between patch temperature and patch area and shape index was statistically analyzed.The results showed that the patch temperature of vegetation and water body was in inverse proportion to patch area and shape index.The patch temperature of construction land was proportional to the patch area,and inversely proportional to the shape index,and there was a threshold so that the plaque temperature tends to a stable value.This shows that it is not without restrictions to change the patch area,shape index can ease urban heat island effect,we can base on the design of the threshold for the class of the design.The results of heat island intensity and land surface classification were superimposed,and the seasonal transition of different types of heat island intensity was calculated.The results show that the intensity of the vegetation is transferred to the low heat island in spring and summer,and the intensity of the construction land is transferred to the high heat island intensity zone.Landscape fragmentation in summer is the largest,In the urban planning layout,attention should be paid to the collocation of water,vegetation and construction land,so as to achieve the effect of alleviating the cold island effect and alleviating the heat island effect in winter.Compared to other types of land,construction land is the most contact,close contact to people.The influence of different land types on the temperature of plots in construction land was analyzed by geography detector model.The data of four seasons are calculated,and the influence of land use in different seasons is different.According to the distribution of land types in the study area,it can be concluded that the influence of dry land and water body on the temperature of construction land is more influential than other areas.The influence of different land-type interactions on the temperature of construction land is greater than that of the single land use.The study is of great reference significance to the ecological environment construction in Changshu City.In the study of urban temperature,it is necessary to consider the influence of surrounding land types comprehensively.