Creating Harmony From Dissonance in Model Development: A Business Approach
Dispersion model development is characterized by a relatively low cost to develop a model, followed by an enormous cost to validate the models under a variety of conditions. Since harmonization in Europe is more of a “bottom up” phenomenon—contrasted to the “top down” approach in the United States— building a framework for model use and development is essential. There will be two essential parts of this framework. First, there should be a hierarchy of models that can be used to analyze situations. Simplistic models are adequate where there is clearly no threat to air quality standards. More refined models are necessary as air quality concentrations approach standards. Second, there needs to be framework to develop a sophisticated model in which various research groups in Europe undertake the development and validation of a specific part of a model. Models for the 21st century will have many subroutines to address specific issues including: point sources, stack tip downwash considerations, building wake effects, convective turbulence, line sources, area sources, volume sources, moving sources, puff sources, stack plume rise—both momentum and buoyancy, plume rise from flares, plume rise from buoyant line sources, buoyancy induced dispersion, particulate matter deposition, computations of concentrations for averaging times specified in each nation’s regulations, processors for meteorological inputs that will include computed data at grid points at several elevations, computation of mixing heights, development of an appropriate scheme for sea breeze situations, and the ability to relate to varying surface roughness and anthropogenic heat sources. The creation of a universally acceptable model will involve the development and validation of dozens of subroutines, each one addressing a special topic. Only when all the parts are well designed and tested, will the finished model withstand the scrutiny and gain acceptance of the many regulatory agencies in Europe. Continuing research to improve the subroutines would assure that the model representing the best science would gradually improve over time.