Specification of boundary values and source characteristics for ozone prediction in a complex airshed

The National Institute for Environmental Studies, Tsukuba, Japan, has carried out a series of summer-time field studies in urban and rural settings which include detailed measurements of meteorology and pollution concentrations both at the surface and aloft. The purpose of such studies is to better understand the medium and long range interaction of weather with pollutant emissions. And from this understanding develop appropriate models to predict pollutant levels, particularly those such as ozone which are formed in the atmosphere. One such model is the three-dimensional Urban Air-Shed Model which has been adapted to calculate ozone concentrations in the Tokyo area. However, accurate calculations require proper specification of boundary conditions and of emission characteristics. This study is directed towards determining the sensitivity of the ozone prediction procedure to variation in boundary values; and to variation in the (speciated) source fingerprints which chemically characterize the emission of organics. The effects of using different boundary assumptions are compared. All calculated results are also compared, using actual meteorology, with a large data set of ambient concentrations (NO, NO₂, O₃, and 17 hydrocarbons) collected both aloft and at ground-level in the Tokyo region in the summer of 1981.