Numerical simulations of the influence of the Vancouver metropolitan area on summertime atmospheric circulations during EPiCC

One of the objectives of the Environmental Prediction in Canadian Cities (EPiCC) project is to use the Canadian Urban Modeling System to investigate the influences of urban environments on mesoscale atmospheric circulation and other meteorological phenomena and processes. Those processes are of particular importance for air quality modeling where people live. In this context, the present study focuses on a 2008 typical summer event occuring in the metropolitan area of Vancouver, Canada. Numerical simulations are performed using three nested grids at 2.5km, 1km and 250m over the urban area. Synoptic forcings and intial conditions are provided by the regional operational weather forecast model at the resolution of 15km. Results are compared with surface measurements (energy fluxes sites) and ground based atmospheric soundings, such as measurements from a ceilometer, a tethered balloon deployed during 24 hours, and from a Lidar. The influence of the city on local circulations (including sea breeze) is analysed and the way those processes are represented in the model are investigated.