Swamy Gsnvksn, Nagendra S M Shiva, Schlink Uwe
a Department of Civil Engineering , Indian Institute of Technology Madras , Madras , India.
b Department of Urban and Environmental Sociology , Helmholtz Center for Environmental Research-UFZ , Leipzig , Germany.
J Air Waste Manag Assoc. 2017 Oct;67(10):1080-1091. doi: 10.1080/10962247.2017.1325417. Epub 2017 May 16.
The combined action of urbanization (change in land use) and increase in vehicular emissions intensifies the urban heat island (UHI) effect in many cities in the developed countries. The urban warming (UHI) enhances heat-stress-related diseases and ozone (O) levels due to a photochemical reaction. Even though UHI intensity depends on wind speed, wind direction, and solar flux, the thermodynamic properties of surface materials can accelerate the temperature profiles at the local scale. This mechanism modifies the atmospheric boundary layer (ABL) structure and mixing height in urban regions. These changes further deteriorate the local air quality. In this work, an attempt has been made to understand the interrelationship between air pollution and UHI intensity at selected urban areas located at tropical environment. The characteristics of ambient temperature profiles associated with land use changes in the different microenvironments of Chennai city were simulated using the Envi-Met model. The simulated surface 24-hr average air temperatures (11 m above the ground) for urban background and commercial and residential sites were found to be 30.81 ± 2.06, 31.51 ± 1.87, and 31.33 ± 2.1ºC, respectively. The diurnal variation of UHI intensity was determined by comparing the daytime average air temperatures to the diurnal air temperature for different wind velocity conditions. From the model simulations, we found that wind speed of 0.2 to 5 m/sec aggravates the UHI intensity. Further, the diurnal variation of mixing height was also estimated at the study locations. The estimated lowest mixing height at the residential area was found to be 60 m in the middle of night. During the same period, highest ozone (O) concentrations were also recorded at the continuous ambient air quality monitoring station (CAAQMS) located at the residential area.
An attempt has made to study the diurnal variation of secondary pollution levels in different study regions. This paper focuses mainly on the UHI intensity variations with respect to percentage of land use pattern change in Chennai city, India. The study simulated the area-based land use pattern with local mixing height variations. The relationship between UHI intensity and mixing height provides variations on local air quality.
城市化（土地利用变化）和车辆排放增加的共同作用加剧了发达国家许多城市的城市热岛（UHI）效应。城市变暖（UHI）由于光化学反应会增加与热应激相关的疾病和臭氧（O）水平。尽管UHI强度取决于风速、风向和太阳通量，但地表材料的热力学特性可在局部尺度上加速温度分布。这种机制改变了城市地区的大气边界层（ABL）结构和混合高度。这些变化进一步恶化了当地空气质量。在这项工作中，我们试图了解热带环境中选定城市地区空气污染与UHI强度之间的相互关系。使用Envi-Met模型模拟了钦奈市不同微环境中与土地利用变化相关的环境温度分布特征。发现城市背景、商业和住宅用地的模拟地表24小时平均气温（地面以上11米）分别为30.81±2.06、31.51±1.87和31.33±2.1ºC。通过比较不同风速条件下的白天平均气温和日气温，确定了UHI强度的日变化。从模型模拟中，我们发现0.2至5米/秒的风速会加剧UHI强度。此外，还估计了研究地点混合高度的日变化。发现住宅区在午夜时分的最低混合高度估计为60米。同一时期，位于住宅区的连续环境空气质量监测站（CAAQMS）也记录到了最高的臭氧（O）浓度。
已尝试研究不同研究区域二次污染水平的日变化。本文主要关注印度钦奈市UHI强度随土地利用模式变化百分比的变化。该研究模拟了基于区域的土地利用模式以及局部混合高度变化。UHI强度与混合高度之间的关系提供了当地空气质量的变化情况。
