Scientists involved in regional-scale measurement and modeling efforts within ACP discussed a number of recent successes. In addition to each group's "stand-alone" successes, the modeling and measurements groups combined to interpret results and to infer key processes involved in the photochemistry for several different locations and their associated field campaigns (the Southern Oxidant Study in Nashville, TN; the NARSTO campaigns of 1995 and 1996; and several NARE fields intensives over the Northeastern U.S., Canada, and the North Atlantic Ocean). Maintaining these collaborations in the future will aid in planning, executing, and analyzing future field campaigns aimed at understanding the effects of energy use on atmospheric processes. Some key successes are described below.

 Argonne National Laboratory (Paul Doskey, Weigang Gao, Marv Wesely). The Argonne group improved their dry deposition module (driven with satellite data) for use in models. The dry deposition velocities of a number of key tropospheric trace gases can be simulated using this approach. The group also developed emission modules using the same database. Their measurements of the PAN dry deposition velocity, 0.1-0.2 cm s^-1, are a welcome addition to the field, and are lower than previously believed. In addition, the group studied the fast chemistry of NO/NO₂/O₃ in the surface layer and the associated flux divergence.

Brookhaven National Laboratory (Larry Kleinman, Sandy Sillman, and many others). This group used a box model driven by observed concentrations to understand O₃ production rates, the sensitivity to NO_x and NMHCs, radical concentrations, and the signatures of NO_x and NMHC limited conditions. They derived analytical equations to describe O₃ production rates and its sensitivity to NO_x and NMHCs. They compared the Eulerian model (Sillman, 5-km resolution, Univ. of Michigan) simulations from the Southern Oxidant Study (Nashville, TN) with observations and looked at the effect of emission controls.

University of Iowa (Greg Carmichael, Mahesh Phadnis). This group has made use of the STEM II and III regional models to study photochemical and aerosol interactions. They have applied the models to East Asia, and will apply them to help plan and/or analyze future field campaigns in the southeastern and southwestern United States. In addition, they have made use of automatic differentiation in conjunction with regional models to understand how changes in total ozone affect UV-fluxes.

Lawrence Livermore National Laboratory/University of Michigan (Cyndi Atherton, Joyce Penner, Sandy Sillman, John Walton). This group applied its three dimensional global model (GRANTOUR) to the NARE region (northeastern U.S. to Europe) to help interpret NARE field campaign measurements. They used chemical signatures (as indicated by O₃/NO_y, O₃/CO, etc.) to show the existence of four distinct photochemical regions. Their predicted seasonality of O₃/CO agreed the measurements reported by Parrish et al., showing a positive slope in summer, and negative in winter. Because their model updates meteorology every six hours, they also showed the transport of O₃ occurred in "episodes" in the NARE region with a 4-7 day frequency, similar to frequencies observed.

Pacific Northwest National Laboratory (Carl Berkowitz, Elaine Chapman, Chris Doran, Jerome Fast). This group used a particle dispersion model to show the origin of O₃ layering, as evidenced in the NARE 92 and 93 campaigns, and the NARSTO 95 field measurements. They also developed a 3-km resolution mesoscale model that uses assimilated meteorology. This model will be used for scoping studies for the Phoenix 1998 measurements. Additionally, they have used a regional-scale chemical model with a 20-km horizontal resolution to simulate regional photochemistry and stratosphere-troposphere exchange.