中文摘要：

应用WRF及其耦合的城市冠层模式（UCM,Urban Canopy Model）,对2004年6月底—7月初受副热带高压和台风外围气流影响下发生在广州地区的一次高温天气过程进行了数值模拟。考察了WRF/UCM对＂城市热岛＂及城市高温天气模拟的应用效果。三个不同设计的模拟试验表明,E-UCM试验（新土地利用资料,耦合UCM模式）比E-BPA试验（新土地利用资料,BPA方法）和E-NOU试验（旧土地利用资料,耦合UCM模式）更好地模拟出了城区2 m高度温度的演变,平均绝对误差最小。尤其在夜间,E-UCM试验成功地再现了夜间热岛的形成及分布。城区及郊区地表能量平衡差异的分析表明,日间城区高温与低反射率引起的短波辐射吸收增加有关,由于城区缺少水汽蒸发蒸腾冷却过程,大部分能量收入被分配为感热加热大气。夜间,地表能量收入来自土壤热通量的向上输送,收入能量除部分用于长波辐射之外,由于城区潜热通量小,其余部分仍主要以感热形式加热大气。夜间热岛的形成与感热加热的持续有关,有利于夜间高温的维持。

英文摘要：

By applying the WRF model and its coupling Urban Canopy Model（UCM） to simulate a heat wave event,which occurred around Guangzhou City in late June 2004 into early July in a background of descending airflows at the periphery of a tropical cyclone and subtropical high,this paper evaluated the performance of a coupled WRF/UCM modeling system during its simulation of the heat wave and ＂Urban Heat Island＂（UHI）.Results from three differently designed experiments reveal that the experiment E-UCM（new land-use data,coupling UCM） reproduces a better 2-m temperature evolution in the urban area with minimum absolute average errors when compared with the other two experiments,E-BPA（new land-use data,BPA-Bulk Parameterization Approach） and E-NOU（original USGS land-use data,coupling UCM）.Especially during the night,E-UCM more successfully captures the temporal and spatial distribution of the nighttime UHI.Difference in surface energy balance between the urban and non-urban area shows that lower daytime values of albedo causes the urban area to absorb more solar radiation;due to the lack of vegetation in the urban area,which inhibits cooling by evapotranspiration,most part of the incoming energy is partitioned into sensible heat flux to heat the urban area and enhance the heat waves.During nighttime,the incoming energy in the urban area is mainly from soil heat flux;although some is partitioned as outgoing long wave radiation,most of the soil heat flux is partitioned into sensible heat flux due to the small latent heat flux at night.It contributes to the development of nighttime UHI and increases the magnitude and duration of heat waves within the city.