Study On The Current Situation Of Heat Island Effect In Beijing And The Influencing Factors Of Greenbelt On Mitigating Heat Island Effect

In the process of urbanization,the temperature of urban area is higher than that of suburban area because of the change of underlying surface environment.This phenomenon is called heat island effect.Although the urban heat island effect does not directly cause economic losses and casualties,it indirectly affects the production and life of citizens.In this study,the current situation of heat island effect in the main urban area of Beijing's Fifth Ring Road in summer of 2017 was studied,and 65 urban greenbelts of different sizes and types in Beijing's Fifth Ring Road were selected to study the influencing factors of urban greenbelts' internal temperature,the quantitative range of greenbelts' cooling and its influencing factors through a large number of data linear fitting and control variable method.The following conclusions were drawn:At present,there is a significant heat island effect in the main urban area of Beijing.From the second ring to the fifth ring,the proportion of high temperature region decreases gradually,while the proportion of low temperature region increases gradually.The highest proportion of high temperature was found in the southwest and Southeast quadrants,and the highest was in the northeast and northwest quadrants.Large areas of high temperature heat island areas are mostly old cottage residential areas,factories,wholesale markets,railway stations and so on.The cold island distributes in a large area from the Fourth Ring to the Fifth Ring,and the distribution in the Fourth Ring is mostly large urban parks.(2)The analysis of influencing factors of greenbelt interior temperature concludes that the smaller the area of greenbelt,the higher the interior temperature.When the area of green space is 1-10 hectares,the average temperature inside the green space will decrease with the increase of the area.When the area is larger than 10 hectares,the average temperature inside the green space does not change much.There is no significant correlation between the temperature inside the green space and the circumference and shape index of the green space.The degree of vegetation coverage in green space is negatively correlated with the temperature inside the green space.When the vegetation coverage increases by 1%,the average temperature inside the green space will decrease by 0.158 C.(3)The analysis of the influencing factors of the cooling range of green space concludes that the smaller the green area is,the smaller the cooling range is.When the area of green space is between0-7ha or the circumference of green space is between 0-1.5km,the cooling range of green space willincrease with the increase of green space area.When the area of green space exceeds 7ha or the circumference of green space is larger than 1.5km,the cooling range of green space no longer increases with the increase of green space area.The cooling range of green space generally stays between 150 m and 250 M.When the green space area is the same,the cooling range of green space decreases with the increase of green space circumference,and decreases with the increase of shape index.(4)The proportion of impervious surface in the surrounding land of urban green space also has obvious influence on the cooling range of urban green space.When the proportion of impervious surface area around green space increases by 1%,the cooling range of green space will decrease by4.01 m under the same green area.The conclusions provide some data and theoretical support for the future development of Beijing and urban green space planning.At the same time,other cities in urban green space planning can provide scientific basis for urban spatial structure and green space layout according to the research results of this paper,in order to achieve the goal of providing a low-heat comfortable living environment for the city to provide a reference basis.