Abstract
The quasi-stational reactive diffusion model of NO and NO2 has been be applied to long-term average concentration.
Some diffusion models with conversion of NO to NO2 by chemical reactions have been presented. Among them, the quasi-stational model by Kimura (1978) can be combine with any diffusion model and it does not include emprical parameter, because it is a pure theoretical model. However, the model gives conversion rate only for short-term average concentration, and we need background concentrations of NO2 and 03, which are sometimes difficult to be obtained. In this' report, these short points are improved.
It will be shown that the background concentrations can be estimated from observed long-term average concetration at a few monitoring stations in a large city, and the estimated values do not strongly denpend on the place of the monitoring station. A convertion formura for long-term average concentrations will be introduced. In this formula, we need a new parameter which corresponds to variation coefficient of short-term concentrations. The formula can convert NOX concentration into NO2 concentration with high accuracy without complex calculation.
The convertion rate for anual average concentration can be approximated by a line with slight curvature in a logarithmic chart, and it agrees well with the regression lines of the corventional statistical models. This model is not only as simpl as a statistical model, but also it theoreticall suports the statistical models.
