【摘要】 文中在综合国外一些较先进的中尺度模式城市作用参数化方案的基础上 ,从城市下垫面结构对城市边界层大气作用的物理机制及实际应用两方面出发 ,对城市下垫面结构和人为活动等因素对边界层结构的影响及中尺度模式中城市化作用的合理体现等问题进行了较全面的考虑 ,改进和设计出能够较全面、细致地描述城市结构对大气边界层动力、热力结构的影响 ,且适合中尺度模式结构特点的城市冠层参数化方案 (UCP) ,并实现了其与MM5模式的耦合。进行了耦合后的UCP方案及采用原城市作用方案的MM5模式对BECAPEX试验期间北京地区气象条件多重嵌套细尺度进行了模拟试验 ,并与观测结果对比 ,结果表明 :相比于MM 5模式中原有表示城市作用的参数化方案来讲 ,设计的UCP方案在很大程度上提高了MM 5模式对城市边界层热力和动力结构的模拟能力。更多还原

【Abstract】 Based on some advanced urban parameterizations for mesoscale model, a urban canopy parameterization (for abbreviation UCP) is developed, in which the effect of urban infrastructure and anthropogenic activity on UBL and rational representation of urbanization in mesoscale model are considered. UCP takes into account following processes of urban :(1)according to the characteristic of real urban underlying surface, all kinds of urban surface parameter in UCP are presented to embody comprehensively the effect of urban on atmosphere;(2)in dynamical effect of urban on atmosphere, traditional surface layer similarity theory is modified to consider characteristic of no constant turbulent monentum flux in urban canopy, and also consider drag force of building on momentum and turbulent kinentic energy (TKE), meanwhile the effect of urban building on turbulent length scale is taken into account in TKE calculation;(3)in thermal effect of urban on atmosphere, the effect of no contant turbulent heat flux in urban canopy is not only condisered, but vertical change of net radiation flux and anthropogenic heat flux versus time are condisered;(4)in urban surface energy budget, the effect of urban caopy on surface radiation balance and anthropogenic heat flux are involved based on characteristic of mesoscale model. The UCP is implemented in MM5 by modifying memory module, I/O module including nest structure, Geyno-Seaman PBL scheme and SLAB surface scheme. With requirement and foundation of atmospheric study in Beijing area, MM5 coupled UCP(for abbreviation MM5 UCP) is validated and compared with IOP observation and automatic meteorological station data to verify its capability to simulate urban atmosphere. The results illustrate that UCP versus traditional urban parameterization in MM5, it can make MM5 reproduce main characteristic of winter UBL in Beijing, which include urban heat island and its diurnal evolvement , nocturnal elvated inversion in downtown area, and some dynamic stucture such as TKE peak at the top of urban canopy, lower wind speed in urban surface layer and so on. Consequently, MM5-UCP can be used to study furtherly the characteristic and formation of UBL in Beijing area.更多还原