Models Urban to Regional Scales

Models currently in use for developing control strategy options are grid-based, or Eulerian, models, the 

FIGURE 16.20 Schematic of Lagrangian-type trajectory model (adapted from Wayne et at., 1973). 

FIGURE 16.21 Schematic illustration of the grid used and treatment of atmospheric processes in one Eulerian airshed model (adapted from Ames et al., 1978). 

While such models are becoming increasingly sophisticated and capable of incorporating more detailed emissions, meteorology, and chemistry, there remain a number of important issues and uncertainties in their inputs and, hence, predictions. A few of the important parameters are discussed briefly in the following. 

For example, Kumar and Russell (1996) examined the effect on predicted ozone levels in the Los Angeles area of two different approaches now used for incorporating meteorology into a grid-based Eulerian model. The diagnostic approach is based on field measurements of the needed meteorological variables and in- 

---