快速城市化区域城市热岛及其环境效应研究

以广州为中心的珠江三角洲区域城市化十分迅速,城市热岛对城市生态环境影响极大。城市热岛及其环境效应的研究有利于城市合理规划和可持续发展。利用中尺度模式MM5模拟广州地区的城市热岛效应,模式采用四重嵌套网格,最高水平分辨率为1km。研究通过数值模拟结果与自动气象站观测的气温和ETM+热红外波段反演的地温的对比,表明该方案能准确模拟地表的温度状况和城市热岛的环境效应。研究还表明城市干岛与热岛相伴而生,02时和11时广州热岛强度较小,相对湿度较高,20时热岛强度达到最大,城区相对湿度则最低;因城市热岛的存在,改变了原盛行风向,减弱了风速,且湿地、绿地、河流廊道等景观分割了城市热岛和干岛,增加了其破碎度,调节了城市气候。

Research on Urban Heat Island and its Environmental Effects of Rapidly Urbanized Regions

The regions were urbanized more and more rapidly in Zhujiang Delta. The Urban Heat Island (UHI) became more and more serious and affected the ecological environment seriously. The research of UHI and its environmental effects was propitious to the city planning and its continuable development. The non-hydrostatic mesoscale model MM5 was used to simulate UHI and its environmental effects in Guangzhou with four-fold nesting and the finest mesh resolution of 1 km. The air temperature from MM5 and automatic weather stations (AWS) was very close at 11:00, and the land surface temperature (LST) from MM5 and the Landsat Enhanced Thematic Mapper Plus (ETM ) had similar characteristic. The result shown the project of MM5 could simulate UHI and its effects well and truly. The UHI appeared with the Urban Dry Island (UDI). The Urban Heat Island intensity (UHII) was less at 02:00 and 11:00 than at 20:00, and the relative humidity had the reverse change characteristic. The prevailing wind directory and speed were changed in the regions of UHI. The result also showed that wetland landscape, urban green-land and river availably divided up the UHI and UDI, and caused their fractions increasing. Therefore, the three landscapes adjusted the urban climate effectively.