Abstract: Simulation of air pollutants depends on the correct representation of both atmospheric emissions and the urban weather. To represent the urban atmosphere in WRF-Chem, the urban physics option needs to be activated. Nevertheless, the correct configuration required updating the default values of the geomorphological and radiative properties of the urban classes inside the simulated domain. In this work, we gather global and local databases to create the domain urban classification, and to estimate the building height, the anthropogenic heat, the urban fraction, the albedo, and the road-width parameters of this new urban classification. We performed simulations using the Urban Canopy Model (UCM) in WRF-Chem for a week in August 2022. The simulation domain is centered in the Metropolitan Area of Sao Paulo and has a spatial resolution of 1 km. Two simulations are carried out, a scenario without UCM and a second scenario with UCM activated and with updated urban parameters values. Meteorological parameters are compared against observations from CETESB air quality network. Preliminary results showed an improvement in the spatial variation of meteorological parameters. In the case of air temperature, despite both scenario simulations being close, the updated scenario presents a better representation of nocturnal temperature. Analysis of planetary boundary layer height, relative humidity, wind speed and direction are being analyzed and will be presented. The database is useful for urban studies and the methodology is suitable to estimate different properties for other urban classification like Local Climate Zones (LCZ) or other urban physics models such as Building Environment Parameterization (BEP) or Building Energy Model (BEM), not only in São Paulo but in other cities of the region.

Keywords: WRF-Chem, UCM, Urban climate, São Paulo.