南京地区高温天气下城市化影响的模拟研究
投稿时间: 2017-06-07  最后修改时间: 2017-08-19  点此下载全文
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马红云 南京信息工程大学 气象灾害预报预警与评估协同创新中心/气象灾害教育部重点实验室, 江苏 南京 210044 mhypony@126.com 
董轩 南京信息工程大学 大气科学学院, 江苏 南京 210044  
孙岑霄 南京信息工程大学 大气科学学院, 江苏 南京 210044  
基金项目:江苏省大学生创新创业训练计划平台资助项目(201510300045Z);国家自然科学基金资助项目(41641046)
中文摘要:利用WRF(Weather Research and Forecasting)模式耦合单层城市冠层模式,研究了南京地区一次高温热浪过程(2013年8月5—10日)中气溶胶的辐射效应、城市扩张对边界层的影响和它们间的相互作用。结果显示,由于气溶胶的直接辐射效应,在白天,南京近地面温度平均降低约0.11 ℃,净辐射平均降低约12 W/m2;城市扩张使近地面温度增加约1.7 ℃,在本次试验过程中,城市扩张的增暖效应明显强于气溶胶冷却效应。另外,由于城市扩张后产生了较强的增暖作用,加强了周围气流的辐合运动,城市区域风速平均增加约0.8 m/s。白天潜热通量的减少与感热通量的增加导致城市边界层内温度升高,并且城市增暖引起的上升运动将气溶胶抬升至更高层,使边界层更不稳定,气溶胶与城市边界层稳定性之间可能存在正反馈。
中文关键词:数值模拟  城市扩张  气溶胶辐射 效应  反馈
 
Numerical simulations of urbanization impacts under hot weather conditions in Nanjing
Abstract:Nanjing is one of the most important industrial cities in China,and its local land cover and environment have been modified over the past several decades.In this paper,with three scenarios(URBA,NURBA,URBNA) integrated by the WRF model,we investigate the effects of aerosol and urban expansion to boundary layer meteorology over Nanjing,China,with the aim of comparing the effects of aerosol and urban expansion during a heat wave,and discuss the feedback between them.Through the observed data validating the variable 2 m temperature and 2 m relative humidity from the model,the WRF model is capable of capturing the features of urban meteorological variables in the Nanjing region during a hot weather episode.Based on the Aerosol-Aware Thompson microphysical scheme and two types of aerosol(ice-friendly aerosol NIFA and water-friendly aerosol NWFA),the cooling effect caused by aerosol is apparent and dominate at daytime.The radiative forcing leads to a decrease of -0.11 ℃ in 2 m temperature and -12 W/m2 in net radiation at daytime,both of which peak at 0800 LST and 1800 LST.The surface air temperature of Nanjing increases by 1.7 ℃ due to urban expansion.This in turn leads to an increase in wind speed of around 0.8 m/s,for which the increase due to heat island effect is greater than the decreased due to surface roughness.As for the 2 m temperature,the urbanization-warming effect is stronger than the aerosol-cooling effect under a hot weather episode.The latent heat flux decreases and sensible heat flux increases in the daytime,resulting in a warmer atmospheric temperature(below 1.6 km) in the daytime than in the nighttime.Urban-induced local updraft brings the aerosol to a greater height,especially in the daytime.As a result,a positive feedback may exist between the aerosol and the stability of the urban boundary layer.It is important to note that the warming effect of black carbon is not considered in this paper.
keywords:numerical simulation  urban expansion  aerosol radiative effect  feedback
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