Modeling Temporal and Spatial Characteristics of Nitrogen dry Deposition in the Phoenix Metropolitan Area

1. Annual fluxes: The simulated annual NOx dry deposition fluxes for the year 1998 (Table 1) show that N deposition in the urban core area was significantly elevated above deposition at the nonurban Palo Verde site. Since the land use characteristics around the urban stations are similar we conclude that differences in the simulated deposition fluxes were caused mainly by differences in the measured pollutant concentrations. The Greenwood station is close to a major highway and therefore characterized by very high deposition rates, which are not representative for a larger area. The simulations showed a marked seasonal pattern for the NOx dry deposition fluxes, peaking over the winter months and declining during the summer (Figure 2).