| Urban climate is not only an important factor affecting regional and global climate,but also a key factor affecting urban livability.In the process of urbanization,with the rapid increase in the size of cities,the height of buildings,and the increase in building density,microclimate issues such as urban heat islands caused by the city’s unique spatial patterns have attracted increasing attention.With the progress of computer technique,the characteristics of numerical simulation technology with high resolution,predictability and low cost are widely used to study urban thermal environment problems.Researching the correlation between the three-dimensional and the urban thermal condition,it will provide a reference for the urban thermal environment change mechanism and model simulation,and is of great worth to the research process of urban climate condition assessment.In this study,Jinan Gao Xin Zone was used as the research area.Using measured data and ENVI-met4.3 numerical simulation results,the urban morphological parameters(building density,greening rate,greening coverage rate,volume ratio,space ratio,spatial congestion and sky visibility)affect the mechanism of urban thermal environment formation at 10:00 in the summer,and based on Spearman rank correlation coefficient analysis,the correlation between various spatial morphological indicators and urban thermal environment is studied.And by changing the vegetation types in the study area,the comparative analysis of the five common tree species(Golden Maple,Acacia,Sycamore,Pine,and Pagoda)on the cooling,humidification,and energy saving of the outdoor thermal environment in high-rise residential areas,The conclusions of this study are as follows:(1)Comparison of measured data and numerical imitation outcome,it is discover that the RMSE of monitoring point 1 is 0.73℃and MAPE is 1.92%;the errors are within the allowable extent and the simulation outcom are good.The research on the application of ENVI-met simulation analysis of urban microclimate environment has been relatively mature.(2)The results show that in the vertical direction,the three-dimensional morphology of vegetation and buildings have different ranges of influence on air temperature(T_a).The BCR、FAR、cubic index,and SCD indexes are significantly positively correlated with T_a above 12.5m,while greening rate and vegetation fraction are significantly negatively correlated with T_abelow 12.5 m.(3)When the commercial land is below 12.5m,the temperature is main influenced by the shadow of the building,there is no significant correlation between building density and air temperature,and FAR and cubic index are significantly negatively related to the temperature.Due to the spatial layout rules of residential land,the correlation of UMPs reached a confidence level of 0.05 when it was less than 22.5 m.(4)The spatial scale and the grid resolution simulated by the model are have a great influence on the relationship between urban form and urban thermal environment.The optimal spatial scale depends on the grid resolution and the specific overview of the study area.Among the seven UMPs,the FAR and cubic indexes are most affected by the spatial scale.In comparison,the SVF is less affected by the spatial scale.(5)The cooling and humidification concequents of different tree species are different.From 7:00 am to 18:00 pm,the cooling and humidification ranges of the 5 tree species are0.06～1.21℃ and 1.99～7.22%,respectively.At 14:00 in the afternoon,the cooling and humidifying concequent of the phoenix tree is the best.The highest degree of temperature reduction and humidification can reach 2.6℃and 18.34%,and the acacia has the worst cooling and humidifying effect.(6)The 3D cumulative energy saving benefits of different tree species are different.Under the vertical space of 2 m from the ground,the 3D cumulative cooling and energy saving range of the five tree species are 5.16～8.48℃ and 30.92～50.89 k Wh,respectively.Among them,Indus has the best energy-saving benefits,with a cumulative energy saving of 50.89kWh. |
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