张凯,赵天良,曹乐,胡小明,郑小波,杨清健,于超.街道峡谷对近地层风场影响的观测和模拟分析[J].环境科学学报,2019,39(12):4187-4195
街道峡谷对近地层风场影响的观测和模拟分析
- Observation and simulation analyses on influence of street canyon on near-surface winds
- 基金项目：国家重点研发计划试点专项项目（No.2016YFC0203304）；国家自然科学基金（No.41830965，91744209）；江苏省研究生科研与实践创新计划项目（No.KYCX18_1027）
- 张凯
- 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210000
- 赵天良
- 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210000
- 曹乐
- 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210000
- 胡小明
- 俄克拉荷马大学气象学院, 俄克拉荷马州 诺曼 73072
- 郑小波
- 贵州省山地环境气候研究所, 贵阳 550000
- 杨清健
- 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210000
- 于超
- 南京信息工程大学大气物理学院, 气象灾害教育部重点实验室, 气候与环境变化国际合作联合实验室, 气象灾害预报预警与评估协同创新中心, 中国气象局气溶胶与云降水重点开放实验室, 南京 210000
- 摘要：城市街道峡谷结构对近地面边界层的风场环流等气象要素具有重要影响，可导致城市局地空气污染分布发生变化.随着城市化发展及城市空气质量变化，街道峡谷的城市空气污染影响日益突出，分析街道峡谷内部风场成为认识和治理我国城市空气污染的一条重要途径.鉴于目前我国鲜有城市街道尺度大气边界层精细气象观测研究，本文分析了美国俄克拉荷马大学的街道峡谷精细气象观测数据及其FLUENT模拟.结果表明：街道峡谷内风场结构变化依赖大气背景风向，当背景风向平行于街道峡谷走向时，街谷两岸风速几乎没有差异，而在背景风向垂直于街道峡谷走向时，由于高空风进入街谷形成的涡旋气流对街道峡谷风场有补充作用，峡谷两侧中层高度风场差异变大，风速差值大约为0.5 m·s-1，且街道峡谷两岸风速差异得到了FLUENT模式的验证，但模式对迎风岸的风速模拟存在高估，模拟的中层高度处两岸风速差值为1.6 m·s-1.观测资料分析揭示大气边界层稳定度条件对街道峡谷内风场分布也有很大影响，中性稳定条件下街道峡谷两岸近地层风速差异最大，输送进入峡谷空间的风速增量比原峡谷内风速大约高1倍，其它稳定度条件下街谷两岸风速差异被削弱.
- Abstract：The structures of urban street canyon play an important role in the near-surface meteorological elements such as wind field circulation, which can affect the distribution of urban air pollutants. With the development of urbanization and changes in atmospheric environmental quality, the impact of street canyons on urban air pollution has become increasingly prominent. Analyzing the structure of wind field inside street canyons has become an important way to understand and solve the problem of air pollution. In view of the lack of fine meteorological observation in the atmospheric boundary layer at urban street scale, this paper analyzes the fine observation data of the street canyon in the University of Oklahoma and conducts the FLUENT simulation. Results show that the distribution of the wind field within the street canyon is largely dependent on the atmospheric background wind direction. When the background wind direction is parallel to the street canyon, there is almost no difference in wind speed between the south and north sides of street canyon. While perpendicular, the difference of wind speed between two sides at mid-level height becomes the largest because of the supplement of vortex flow caused by the high-altitude wind entering the street canyon, the wind speed difference is about 0.5 m·s-1. The wind speed differences between two sides of the street canyon are verified by FLUENT. However, the modeling provides an overestimation of wind speed on the windward shore, the simulated mid-level difference is about 1.6 m·s-1. The stability of atmospheric boundary layer also has a great influence on the wind field by analyzing the observation data, the difference of wind speed between two sides of street canyon reach maximum under neutral conditions of stability in the near-surface layer. The increment of wind speed by delivery into the street canyon is about twice as high as the normal winds in the canyon. The differences in wind speed between the two sides of street canyon decline under other stability conditions.
