Roles of Urban Tree Canopy and Buildings in Urban Heat Island Effects: Parameterization and Preliminary Results
Roles of Urban Tree Canopy and Buildings in Urban Heat Island Effects: Parameterization and Preliminary Results
复制标题
DOI：
10.1175/jamc-d-11-0228.1
复制
发表时间：
2012-10-01
影响因子：
3
通讯作者：
Landry, Laura
中科院分区：
文献类型：
--
作者：
Loughner, Christopher P.;Allen, Dale J.;Landry, Laura
城市热岛（UHI）效应会加剧热浪和空气污染。在这项研究中，通过将树木、土壤和草纳入耦合的天气研究和预报模型以及城市冠层模型 (WRF-UCM)，研究了华盛顿特区和马里兰州巴尔的摩大都市区极端热浪期间城市树木对城市热岛的抑制影响。通过对道路和建筑物旁边的这些自然表面的影响进行参数化，修改后的 WRF-UCM 可用于研究城市树木、土壤和草地如何抑制城市热岛效应。修改后的模型运行时，城市道路上的树木覆盖率为 50%，城市街道的宽度减少了 10%，以便为道路和建筑物旁边的土壤和草地腾出空间。结果表明，平均所有城市地区，由于树木遮荫和蒸散，增加的植被使城市街道峡谷的表面空气温度降低了 4.1 K，路面和建筑墙壁温度分别降低了 15.4 和 8.9 K。这些温度变化顺风传播并改变与切萨皮克湾微风相关的温度梯度，从而改变海湾微风的强度。建筑高度对城市热岛效应的影响表明，商业建筑高度降低 8 m，住宅建筑高度降低 2.5 m，会导致白天地表和近地表气温升高 0.4-K，因为建筑物遮阳较少，而夜间温度会降低 1.2-K，因为城市街道峡谷中的长波辐射捕获较少。
Urban heat island (UHI) effects can strengthen heat waves and air pollution episodes. In this study, the dampening impact of urban trees on the UHI during an extreme heat wave in the Washington, D. C., and Baltimore, Maryland, metropolitan area is examined by incorporating trees, soil, and grass into the coupled Weather Research and Forecasting model and an urban canopy model (WRF-UCM). By parameterizing the effects of these natural surfaces alongside roadways and buildings, the modified WRF-UCM is used to investigate how urban trees, soil, and grass dampen the UHI. The modified model was run with 50% tree cover over urban roads and a 10% decrease in the width of urban streets to make space for soil and grass alongside the roads and buildings. Results show that, averaged over all urban areas, the added vegetation decreases surface air temperature in urban street canyons by 4.1 K and road-surface and building-wall temperatures by 15.4 and 8.9 K, respectively, as a result of tree shading and evapotranspiration. These temperature changes propagate downwind and alter the temperature gradient associated with the Chesapeake Bay breeze and, therefore, alter the strength of the bay breeze. The impact of building height on the UHI shows that decreasing commercial building heights by 8 m and residential building heights by 2.5 m results in up to 0.4-K higher daytime surface and near-surface air temperatures because of less building shading and up to 1.2-K lower nighttime temperatures because of less longwave radiative trapping in urban street canyons.