Meteorological Processing for a Models-3 Application in the Lower Fraser Valley, British Columbia, Canada

ng.The National Research Council of Canada (NRCC) is currently in the process of developing a new aerosol module for use within the Models-3 framework. The framework will then be tested for an air pollution episode that occurred in the Lower Fraser Valley of British Columbia, Canada (August 1-7, 1993) and compared to model runs already conducted using UAM-V. The Lower Fraser Valley lies in an area of extremely complex topography, with the Coast Mountains lying to the north, The Cascade Range lying to the east and south, and the Strait of Georgia, Vancouver Island and the Pacific Ocean lying to the west. Vancouver, a city of over one million people, lies at the western end of the valley. The topography is challenging from the standpoint of meteorological modelling. The modelling was performed with MM5, operated with two-way nesting and four-dimensional data assimilation (FDDA) using NCEP objective analyses, hourly data from 27 surface weather stations and three-hourly data from one upper air station within the study area. This paper describes the overall objectives of this study, describes the meteorological episode and then presents the results of the meteorolgical modelli