城市中水体布局对大气环境的影响

Impacts of Water Layout on the Atmospheric Environment in Urban Areas

城市下垫面状况在很大程度上决定城市大气物理环境的特征。在城市区域增加湿地等自然地表有利于城市的减温增湿,促使局地流场发生变化,改善局地微气象条件以及大气物理环境。城市规划大气物理环境多尺度数值模拟系统为城市规划大气物理环境定量评估提供了有效的模拟工具。利用该系统中的城市尺度模式模拟了水体布局为集中型和分散型,水体面积占有率分别为4%、8%、12%和16%条件下,城市大气温度、湿度、风速、城市大气扩散条件的变化及其对城市大气环境的影响,利用北京市城市水体气象观测数据,分析了水体周边和商业区、交通区温、湿度的差异,并对模式模拟结果进行了验证,揭示了城市水体布局对城市大气物理环境影响的可能机制。模拟和观测结果显示,城市水体布局会对城市微气象环境产生一定影响。无论分散型或集中型布局,城市水体面积的增加,都在一定程度上使城市气温降低、湿度增加、平均风速增大。比较而言,分散型水体布局对城市区域微气象环境的影响更为显著。

The characteristics of atmospheric physical environment in urban areas are to a large extent determined by the status of underlying surface.An increase in the urban natural surface such as wetlands may help decrease surface temperature,increase humidity,change local flow field,and improve local micrometeorological conditions and atmosphere physical environment.The multi-scale numerical modeling system provides an effective method for assessing quantitatively the atmospheric physical environment in urban planning.In this paper an Urban Scale Model in the system is used to simulate the variability of surface air temperature,humidity,wind velocity,atmospheric diffusion conditions and their effect on urban atmospheric environment on condition of the dispersed or converged water layout with the proportion of urban water area in urban area being 4%,8%,12%and 16%,respectively.Based on meteorological observation data at urban water body sites in Beijing,the differences of air temperature and humidity among the area surrounding water body,commercial areas and traffic zones are analyzed and the simulated results are compared.The results reveal that the layout of urban water body has an obvious effect on urban micrometeorological environment.No matter whether the layout is dispersed or converged,the increase of urban water body area to a certain extent leads to the decrease of surface air temperature,increase of humidity, and enlargement of wind velocity.But water body in the dispersed distribution has a more significant effect on the urban micrometeorological environment than that in the converged distribution.