冷却屋顶对北京城市热环境影响的模拟研究

A simulation study on the influence of cooling roof on the thermal environment in Beijing

中文关键词:  高反照率屋顶  绿色屋顶  城市热岛缓解  WRF模式

英文关键词:High reflective roof  Green roof  Urban heat island mitigation  WRF model

中文摘要:

      两种类型冷却屋顶（高反照率屋顶、绿色屋顶）的研究对于北京夏季城市高温的缓解作用具有重要的意义。耦合单层城市冠层模式（SLUCM）与天气研究与预报（WRF3.8）模式，采用北京市及其外围地区158个站点气象资料评估模式对照案例（case1）的模拟性能，并选取7组不同反照率屋顶案例（case2—4）和不同覆盖比例的绿色屋顶案例（case5—8）进行敏感性试验。研究结果表明：（1）在北京城市区域，高反照率为0.85的屋顶（case4）比绿色占比100%的屋顶（case8）具有更好的降温效果，case4的3 d平均降温可达到0.90℃，而case8降温为0.46℃。（2）屋顶反照率每增加0.1，会导致北京城市区域最高气温降低0.27℃；绿色屋顶比例的增大也会导致温度的降低，每增加10%，最高气温降低0.16℃。（3）两种冷却屋顶对城市热岛也存在显著的影响，在13—14时（北京时），case4与case1对比的城市热岛（UHI）降温最大差值为1.47℃，比case8的城市热岛降温更加明显。（4）在城市区域垂直高度上，冷却屋顶的降温作用可达到1.2 km，同时湍流运动存在明显的减弱；在3 d的12—18时，case4、case8与case1对比，边界层高度平均降低了669与430 m。

英文摘要:

      The study of two types of cooling roofs (high reflectivity roofs and green roofs) has important implications for the mitigation of high temperature in the summer in Beijing. This paper has implemented the Weather Research and Forecasting Model (WRF3.8) coupled with the Single-Layer City Canopy Model (SLUCM) to evaluate the simulation performance of the control case (case1) by this coupled model using meteorological data collected at 158 stations in Beijing. Seven cases with roofs of different albedos (cases2-4) and green roofs with different cover ratios (cases5-8) are conducted for sensitivity studies. The results of the study show that:(1) in the urban area of Beijing, the roof whose albedo is 0.85 (case4) has a better cooling effect than the 100% (case8) green roof, the average temperature in case4 drops by 0.90℃ and the cooling in case 8 is 0.46℃; (2) with the albedo increase of 0.1 in the roof, the maximum temperature in Beijing will decrease by 0.27℃. And the increase in the proportion of green roofs will also result in a decrease in temperature. With every 10% increase in the green roof, the maximum temperature will decrease by 0.16℃; (3) the two types of cooling roofs have significant impacts on the urban heat island (UHI). Compared with case1, the maximum UHI in case4 drops by 1.47℃ during the daytime from 13:00 BT to 14:00 BT, which is higher than the cooling effect shown in case8; (4) the cooling effect of the cooling roofs can reach 1.2 km height above the city, and the turbulence is also significantly reduced. During 12:00-18:00 BT of the three days, compared with case1, the height of the planetary boundary layer in case4 and case8 on average are reduced by 669 and 430 m, respectively.