Research On The Application Of Urban Canopy Parameterization In Wrf

In a rapidly urbanizing world, investigating the effect of urban area to the atmosphere becomes an important problem in the area of numerical modeling. WRF Model provided several option in urban simulation, including slab model and a single layer urban canopy model (UCM). These two approaches are used in simulating weather of Lanzhou between Jan26th and30th in2005. The performance of these two methods in simulating urban effect is compared and analyzed. The default USGS land use data are modified in order to give better description of the real situation in Lanzhou. We found that:(1) In winter, urban canopy acts as a thermal sink, in which way the model using UCM gets more accurate prediction of2m temperature;(2) By including the effect of street canyon on wind, model with UCM gives better prediction of near surface wind,(3) Using UCM can reduce the net downward shortwave and long-wave radiation. Surface sensible heat is also reduced, which may be a result from the lower temperature predicted by UCM,(4) It appears urban canopy tends to suppress the development of turbulance in boudary layer at night, and this effect can be apmlified when cold advection exists.