Comparison And Analysis Of Urban Thermal Environment Changes Between Wuhan And Hangzhou

In recent years,the acceleration of urbanization has led to significant changes in urban surface morphology,resulting in increased impervious water surface,construction land area,and building density,which have negative impacts on urban energy consumption,air quality,and human health.These changes in urban form have significantly affected local urban thermal environment and microclimate,with the urban heat island effect becoming increasingly significant and the differences in urban internal thermal environment becoming more pronounced.Therefore,studying the changes in urban thermal environment and exploring the factors causing these changes is of great significance.This study focused on Wuhan and Hangzhou,two cities with significant urban heat island effects,and used the classification system of local climate zones along with the random forest classification method to classify the local climate zones of the two cities in 2000,2010,and 2020.The atmospheric correction method was used to perform surface temperature inversion and obtain the surface temperature of each LCZ category by superposition analysis of the local climate zone classification map and surface temperature map.Based on land use type,stepwise regression analysis was used to explore the effect of land use type proportion on LCZ land surface temperature.The main research results included the following aspects:(1)From 2000 to 2020,the LCZ area of built types in Wuhan and Hangzhou was constantly expanding,while the LCZ area of natural types was constantly decreasing;In2020,LCZ1 dense high-rise buildings occupy the highest area in both Wuhan and Hangzhou.(2)The LCZ8,LCZ10,and LCZE had the highest LST,while LCZA and LCZG had the lowest LST,and LCZ8 and LCZ10 had greater heat island intensity.Among the land use types of Wuhan and Hangzhou,man-made surfaces had a great influence on LCZ surface temperature by 2020.(3)From 2000 to 2010,the land cover types of Wuhan and Hangzhou showed that the cultivated land area decreased and the construction land area increased in Hangzhou,while the water and cultivated land area decreased and the construction land area increased in Wuhan.The contribution degree of land cover type to the thermal environment of Wuhan is the highest for artificial surface,and the lowest for water,which is negative,which has cooling effect on the urban thermal environment.The contribution degree of man-made surface and cultivated land in Hangzhou is higher,and the lowest is forest land,which is negative,which plays an important role in cooling the urban thermal environment.(4)Based on land cover type and stepwise regression analysis,it can be concluded that water and cultivated land are the most influential factors on LCZ of building types in Wuhan City from 2000 to 2010,while forest land and water are the most influential factors on LCZ of building types in Hangzhou City.However,by 2020,The man-made surface has the largest impact ratio on LCZ of building types in Wuhan and Hangzhou,which may be an important reason for the increase of surface temperature in Wuhan and Hangzhou.