An application of a simple urban canopy model for meso-scale simulation (SUMM) to Tokyo metropolitan area

The meso-scale meteorological simulations using Regional Atmospheric Modeling System (RAMS) were conducted to reproduce the meteorological fields of a high pollutant concentration episode typically seen at Tokyo Metropolitan Area (TMA) in winter time. Although RAMS was used as the basic software, the following improvements of the model were done in order to consider the complex surface condition in towns; (1) detail dataset of anthropogenic heat and water vapor emissions (about 300m mesh) at TMA were produced and incorporated into RAMS surface sub-model, (2) GIS-based dataset of plane area index, frontal area index and mean building height at TMA were produced, and (3) a simple urban canopy model for meso-scale simulation (SUMM) was incorporated. The model geometry of SUMM is assumed to be an infinitely extending regular array of a uniform building composed of six faces (roof, floor, and four vertical walls) with the prefixed urban geometry. SUMM theoretically predicts the energy balance at each face without time-consuming iterations. Compared with the previous models, the improved model provided better results of temperature and wind fields in the high pollutant concentration episode investigated.