基于城市街谷尺度大气污染物扩散的街谷格局优化策略研究

Urban street canyon is one of the important characteristics and spatial forms of cities. It is characterized by serious automobile pollution and the highest daily population density. The 3-dimensional pattern and composition of urban street canyons affect the distribution of atmospheric pollutants inside. What kind of street canyon pattern is conducive to the diffusion of atmospheric pollutants has become an urgent issue to be studied. In this proposal, we will simulate the diffusion of atmospheric pollutants in relation to different street canyon aspect ratios (H/W) and different types of street trees. The ideal three-dimensional street canyons pattern for the diffusion of atmospheric pollutants will be proposed according to the simulation. Then, the typical sites will be selected and the concentration of atmospheric pollutants will be monitored. The street canyon aspect ratio (H/W) will be interpreted with RS images. The atmospheric environments will be simulated by model ENVI-met and OSPM. This proposal will analyze the process and mechanism of the influence of 3-dimensional street canyons pattern on atmospheric pollutant diffusion, will propose an urban architecture pattern conducive to urban atmospheric pollutant diffusion. This proposal is meaningful in revealing the impact of urban 3-dimensional landscape pattern on the atmospheric environment, putting forward scientific support and optimization programs for the control of increasingly urban air pollutants from the perspective of urban planning and landscape pattern optimization.

城市街谷是现代城市的重要空间形式与特征之一，是城市各种公共空间中使用频率最高、汽车尾气污染最严重、日常人口密度最大的公共空间类型之一。街谷的三维格局和构成可改变近地风场进而影响大气污染物的分布，何种街谷格局有利于大气污染物的扩散成为亟待研究的课题。本研究拟通过情景模拟的方法模拟大气污染物扩散与街谷高宽比、行道树配置的关系，提出适宜大气污染物扩散的理想街谷三维格局。在此基础上，选取沈阳市典型的几种街谷类型，现场监测大气污染物的浓度及气象条件，解译街谷三维结构特征，通过大气环境模型ENVI-met和OSPM模拟，分析街谷尺度的三维结构对大气污染物扩散的影响过程和机理，提出适宜城市大气污染物扩散的城市建筑模式。该项研究对揭示城市三维景观格局对大气环境的影响机理，从城市规划和格局优化的角度为日益严重的城市大气污染物的减控提出科学支撑和优化方案有重要意义。

城市街谷是现代城市的重要空间形式与特征之一，是城市各种公共空间中使用频率最高、汽车尾气污染最严重、日常人口密度最大的公共空间类型之一。城市街谷不合理的空间配置和结构会造成城市通风自净能力的降低，大气污染物浓度增高。本项目采用实地观测的方法分析了城市街谷内大气颗粒物分布的影响因素，得出街谷形态和相对湿度的影响大气颗粒物浓度的两个主要因素，且深窄街谷内大气颗粒物的浓度显著低于中宽街谷内的浓度；分析了不同季节行道树对大气污染物的调控作用，行道树对大气颗粒物的削减作用在展叶季较高，尤其对粗颗粒物的削减作用显著高于细颗粒物；比较了不同街谷类型下行道树对大气污染物的削减作用，窄街谷中种植行道树有利于细颗粒物的削减，而宽街谷中种植行道树有利于粗颗粒物的削减。本研究提出适宜城市大气污染物扩散的城市街谷构建模式，为城市下垫面大气污染物的减控提出科学支撑和优化方案。