北京大学校园夏季气象场的数值模拟

Numerical Simulation of Meteorological Fields in the Campus of Peking University in Summer

北京大学校园北部有未名湖等水域和树木冠层绿地,与南部教学、生活区建筑物路面为主的布局在下垫面热力性质上存在显著差异。为定量研究夏季校园内不同区域气象场、舒适度的空间分布和时间变化,为校园活动和游览提供参考,利用北京大学城市冠层模式,结合校园实际下垫面分布情况,进行数值模拟研究。研究结果表明,9月份校园北部温度低于南部,15:00温差可达6.7℃。路面上由于潜热通量小,温度高于其他下垫面,和水面温差最大可达10.6℃。空气湿度北部高于南部。温度分布影响局地风场变化,在15:00产生低温辐散流场。引入表征人体舒适度的温湿指数(THI),路面上有50%时间处于"热"等级,高于其他下垫面的20%。研究结果可以为评估校园环境规划的气象效应提供科学依据。

In the campus of Peking University, there are Weiming Lake, other water body, and agminate green space in the north part, differing significantly on the thermodynamic properties from the south teaching and living part which consist mainly of buildings and roads. In order to study the meteorological and comfort fields in summer, numerical simulation using the city canopy model of Peking University is carried out. In September it is more cool and comfortable in the north of the campus than in the south, and the temperature difference can reach 6.7℃ at 15：00. The temperature of road surface is higher than other surfaces because of the zero latent heat flux. The temperature difference can reach 10.6℃ between road and water. The air specific humidity is higher in the north. The temperature distribution leads to a divergence air flow at 15：00. Thermohygrometric index （THI） is introduced to access human comfort, according to which 50% time of a day is at the ＂hot＂ level above road while above other surfaces only 20% of a day is at this level. This work can provide the scientific basis for assessing the meteorological effect of campus environment designs.