Research On Cold Island Effect Of Urban Park Based On ENVI-met ——A Case Study Of The Downtown Area Of Jinan

The high-speed development of the city has gradually changed the original characteristics of the city,and the urban heat island has been greatly changed.Increasing urban green space area is the most effective solution to improve urban heat island effect.As an important part of urban green space,urban park is an important carrier to improve urban heat island effect,increase urban cold island and optimize urban climate.The research on the cold island effect of urban parks is a new breakthrough for improving the urban thermal environment,promoting urban development and future urban park green space planning.Firstly,this study studies and analyzes the previous literature on the cold island effect of urban parks by using the information visualization software city space.Then,the location distribution of urban parks in the central urban area of Jinan is determined by Arc GIS,and the urban surface temperature is inversed to obtain the relationship between the distribution law of urban parks in the central urban area of Jinan and the surface temperature.In the central urban area of Jinan,four urban parks with different sizes and types and strong cold island effect are selected for field monitoring,and the data of 1.5m high atmospheric temperature and relative humidity,vegetation type,proportion of water body and built environment are extracted.The temporal and spatial laws affecting the cold island effect of urban parks are summarized and summarized,and the relevant data of thermal environment are used as the boundary conditions of later ENVI-met simulation.The characteristics of urban built environment and park in the central urban area of Jinan are extracted,the physical experimental model is constructed,and the thermal environment simulation software ENVI-met is used to simulate the spatial thermal environment.By changing the design parameters such as the shape,vegetation,water body,pavement and surrounding built environment of urban Park,the effects of different influencing factors on the internal and surrounding thermal environment of urban park are compared and analyzed,Summarize the best mode to improve the cold island effect of urban parks.Combined with the urban green space system planning of Jinan and the urban land use characteristics of the central urban area of Jinan,this paper puts forward the optimization strategy of the cold island effect of urban parks,in order to provide theoretical basis and method support for the planning and design of urban parks in the central urban area of Jinan and optimize the urban parks and their surrounding thermal environment in this area.Based on the above analysis,the main research results and conclusions of this study are as follows:(1)Changing the internal elements of urban parks in the central urban area of Jinan and the built environment around the park will have an impact on the cold island effect of urban parks,which has obvious seasonal differences,and the characterization of winter simulation results is more obvious.(2)In the planning and design of the park in the central urban area of Jinan,setting the tree coverage rate to 40% and the water coverage rate to 15 ? 30% can maximize the benefits of the cold island effect of the urban park.(3)Different vegetation types have different cooling and humidifying effects on urban parks.The results are evergreen trees > deciduous trees > grassland.When selecting tree species,trees with cylindrical crown shape and high leaf density should be selected as far as possible.When the conditions for large-area arbor planting cannot be met,appropriate grass and local cover plants can be selected to greening the park.The difference of hard pavement material and proportion will have an impact on the cold island effect of urban parks.(4)Regular park boundaries can more effectively reduce the internal atmospheric temperature of urban parks and improve air humidity.(5)The cold island effect of urban parks is more obvious in the areas with medium and high density and medium and high plot ratio in the central urban area of Jinan.The location and planning of urban parks in their areas can more effectively alleviate the urban heat island effect.