Microclimate Prediction Method Development Base On Impact Assessment Of Urban Park Design Elements

Rapid urbanization is an inevitable factor leading to urben environmental problems such like urban heat island,which is attracting more and more attentions from scholars.Urban greening is one of the important contents of urban development,which is of great significance to urban micro-environment,contributes to reduce urban heat island.This research focus on the urban green park space,which is of great significance to affect the urban microclimate from the perspective of urban planning and design,to comprehensively analyze the design elements and influencing mechanism of the microclimate change caused by the urban green park space,in order to quantitatively evaluate the microclimate effects from green park space and provide a theoretical basis for the city park green space micro climate impact assessment,to support scientific planning and design.This research selected Xingqing Palace Park-the largest comprehensive park in Xi’an city as an example.Firstly,field measurements was carried out in a typical summer day at different levels(inside and outside the park and in different areas of the park),so as to obtain typical summer meteorological parameters(air temperature,relative humidity,wind speed,wind direction).The microclimate changes in different spatial locations around the waterbody of the park were analyzed,and the diurnal variation of the correlation between the distance from the waterbody of the park and the microclimate changes was explored.Based on the design elements within different buffer radius of measuring points,the correlation analysis and multiple regression analysis were used to study the correlation between design elements and the daily variation of microclimate in summer,and the evaluation and prediction model of the impact of urban green park space design elements on microclimate change was further established.This research provides a theoretical basis for microclimate impact assessment and scientific planning and design of urban green park spaces.The main conclusions are as follows:1.Environmetal effects from the park was measured,and the microclimate effects in the park varies at different time periods and spatial directions.The air temperature in the east and north directions was higher than that in the west and south directions,and the relative humidity in the west and south directions was higher than that in the east and north directions.The microclimate changes around the upper and lower wind directions of the waterbody show that the temperature of the measuring point at the lower wind direction is more significantly correlated with the distance from the waterbody in the large range in summer(R~2=0.7765).The temperature of the measuring point at the upper wind direction is more significantly correlated with the distance from the waterbody in the small range(R~2=0.6374),and has an obvious cooling effect in the daytime.At a large scale,the relationship between distance from the waterbody and temperature change is complicated.There is no significant correlation between relative humidity and distance from the waterbody during the whole day.2.Each measuring point of different underlying surface factors make a significant difference was found in the local microclimate,Through the comparison of different underlying surface types,it is found that soil,trees and other underlying surface have significant differences in temperature and humidity,which are the main cooling source types.During the night,trees,soil and grassland has significant differences compare to the other underlying surface types,and hard paving and buildings are the main heating release sources.The composition of underlying surface design elements has a significant impact on local microclimate change,and the influence of waterbody and grassland on temperature and humidity is different in different periods,the influence from design elements on microclimate change is mainly daytime humidification and nighttime cooling,and the greening coverage has a significant effect throughout the day.Based on multiple regression analysis and ten-fold cross-validation method,the temperature and humidity prediction models based on the design elements of green park space and the regression prediction models of the intensity of cooling and humidification in different periods were constructed,and the verification of the accuracy was carried out in this research.