基于局地气候分区的武汉建成空间近地面风环境异质特征分析

Heterogeneity Analysis of Near-surface Wind Environment in Wuhan Built-up Areas Based on Local Climate Zone

为厘清不同类型建成空间风环境异质特征,本文根据局地气候分区(Local Climate Zone,LCZ)对武汉建成空间进行分类,利用城市气象站点2019年全年风速风向监测数据,探讨建成空间整体风速特征及LCZ类间风速风向特征。结果表明:1)整体上来讲,建成空间对城市背景风具有较大削减作用,不管在何种背景风速段下武汉市建成空间平均风速仅为背景风速的1/3;2)建成空间类型间风速存在差异且在不同背景风速段下保持稳定的规律,风速大小呈现大型低层(LCZ8)>零散建筑(LCZ9)>开敞低层(LCZ6)>开敞中层(LCZ5)>开敞高层(LCZ4)>紧凑中层(LCZ2)>紧凑低层(LCZ3),其中LCZ3以发生静风为主,且全年静风频率高达72%,其他LCZ静风频率在11%~40%之间,皆以发生软风为主;3)同一类型建成空间局地主导风向异质特征较为显著,易受LCZ内部建筑形态及周边建成环境的影响。研究成果为延伸LCZ理论在城市气候环境评估中的应用提供相关参考。

To unveil the heterogeneity of wind environments in different types of built-up areas,this paper categorized the built-up areas of Wuhan into different types according to the Local Climate Zone(LCZ)and analyzed the overall wind speed characteristics of built-up areas as well as the wind speed and wind direction characteristics between LCZ categories using the observational data of wind speed and wind direction of urban weather stations in 2019.Results showed that:1)The built-up areas significantly reduced background winds,with the average wind speeds in built-up areas being only one-third of background wind speeds regardless of the conditions of background wind speeds.2)There were prominent differences in wind speeds among different types of built-up areas,and this pattern remained stable across different background wind speed conditions.Specifically,the wind speed differences among LCZ types followed the order of Large low-rise(LCZ8)>Sparsely built(LCZ9)>Open low-rise(LCZ6)>Open mid-rise(LCZ5)>Open high-rise(LCZ4)>Compact mid-rise(LCZ2)>Compact low-rise(LCZ3).LCZ3 experienced mainly calm winds,with a high annual frequency of 72%.The other LCZs experienced soft winds with frequencies of calm winds between 11%and 40%.3)The local dominant wind direction showed significant heterogeneity among the same type of built-up areas,which was easily influenced by building morphology surrounding built environments.