A NEW BOX MODEL TO FORECAST URBAN AIR-QUALITY - BOXURB

This paper presents a model to forecast concentrations of nitrogen dio xide NO2 in urban areas. A box model provides a simple and robust desc ription of air quality in urban areas, especially where emissions data are only available on a fairly coarse grid. BOXURB is a box model wit h some novel features. It can use synoptic observations of the meteoro logy, or numerical forecasts of wind and cloud. Traffic emissions are adjusted by time and day of week, and space heating emissions by degre e hours. The urban heat flux combines an urban heat store adjustment, a space heating term, and the rural heat flux. Pollutants accumulate w ith the onset of light winds. NO2 is forecast by subdividing the NOx i nto its constituents, NO (nitric oxide) and NO2. The subdivision is em pirical for most of the year, but in ozone episodes the photostationar y state is invoked. The forecasts are sent by the Met Office to NETCEN AEA Technology for use in the Department of Environment's Air Quality Bulletin System.