THE DESIN OF URBAN CANOPY PARAMETERIZATION OF MM5 AND ITS’ NUMERICAL SIMULATIONS

Based on some advanced urban paramet erizations 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 inmesoscale model are considered. UCP takes into account following processes of urban: (1) according to the charact eristic 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 charact eristic 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 turbulentlengt hscale is taken into account in TKE calculation; (3) in thermal effect of urban on atmosphere, the effect of nocontant turbulentheat 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 com pared with IOP observation and automatic met eorological 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 charac-teristic 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.