南京地区下垫面变化对城市热岛效应影响的数值模拟

Numerical simulation of the impact of land cover change on the urban heat island effect in Nanjing

利用新一代中尺度研究和预报模式(Weather Research and Forecasting Model,简称WRF)分别耦合多冠层、单冠层和平板模式三种情况进行南京地区2007年8月1日的天气过程模拟,分析不同城市冠层方案对南京气象场的模拟效果。在此基础上,结合模拟效果最好的城市冠层方案,研究南京城市下垫面的变化对其热岛的影响。结果表明:多冠层方案对近地面气温、10 m风场的模拟效果最好;城区的扩张使南京地区近地面气温升高,主要表现为城市区域夜间升温显著,并且导致热岛强度明显增强;城市扩张后,城区白天风速大范围地减小,同时热岛环流更加显著,且具有明显的城市热岛的"下游效应"。

In this paper,the Weather Research and Forecast Model( WRF) is coupled with Surface-Layer Scheme,Single-Layer Urban Canopy Model and Mingle-Layer Urban Canopy Model respectively to evaluate the simulation effect of various parameterizations on the weather conditions on 1 August 2007 in Nanjing. The best urban parameterization scheme is coupled into WRF to study the impact of land cover change on the Urban Heat Island( UHI) effect in Nanjing. Results show that the Mingle-Layer Urban Canopy Model shows the best simulation effect for surface temperature and 10 m wind field. Urbanization makes surface air temperature increase over the region,especially at night and thus intensifies the UHI effect. After urbanization,the wind speed in the downtown area decreases obviously while the Urban Heat Circulation occurs more apparently. There also exists the downstream effect of UHI in Nanjing.