Search On Study On The Heat Island Effect And Its Temporal And Spatial Changes In The Process Of Urban Expansion In Shenyang

Along with the development of the cities in our country,in order to meet the needs of urban construction,urban soil,water,and between vegetation and land cover types by cement,asphalt,metals gradually replaced with opaque surface,speed up the resulting surface water evaporation,runoff,water quality decline and a series of ecological environment problems,the most obvious feature is the decrease of surface vegetation,the appearance of heat island effect.Therefore,it is of great significance to study the changes of its thermal environment to optimize urban functional zoning and sustainable urban development.In this paper.taking Shenyang as an example,Landsat remote sensing images of the third period in 2001,2006 and 2014 were selected,and mixed pixel decomposition model of linear spectrum was used to extract impermeable water surface in each period,and surface temperature was retrieved based on the radiation equation method.Spatial statistics and mean standard difference were used to study the evolution rules and characteristics of urban expansion and thermal environment in the above-mentioned space and time.On the basis of the above analysis,the coupling relation between urban expansion and heat island effect is explored by means of superposition analysis and regression analysis.After that,the Ca-Markov model of urban thermal environment simulation and prediction was constructed to predict the urban thermal environment distribution pattern of Shenyang in 2022.The following conclusions are mainly drawn:(1)From 2001 to 2014,the impermeable water surface area of the city increased continuously,the urban space continued to expand,and the expansion intensity presented a certain non-linear metric(2)The heat island effect of Shenyang is obvious,and the overall situation is deteriorating.The area proportion of the high-temperature area gradually expands,and its landscape index shows certain rules.(3)The green patch area is in the range of 2-2.2 hectares,and the effect of reducing the heat island effect is the most "economic".Therefore,appropriately increasing green space and controlling urban construction to expand will play a positive role in alleviating urban heat island effect.(4)The impervious coverage value is in good agreement with the spatial layout of thermal environment.Areas with a higher impervious coverage value have a higher surface temperature value,and the urban heat island effect is obvious,and vice versa.If other conditions remain unchanged,for every 0.1 increase of impermeable surface coverage value,the normalized surface temperature will rise by 0.01 to 0.02.(5)The predicted results show that the overall situation of thermal environment in Shenyang tends to be stable in 2022,and the thermal environment in some regions tends to be intensified.The predicted results provide important basis for Shenyang city to control heat island effect.