I agree that the steady-state model would not be great when used for distances extending greater than a few kilometres. And that more advanced models such as CALPUFF air model would work better.
- Correct, Rush. As the decades progress, the models shall continue to improve.
At one point considered state-of-the-art, CALPUFF goes a few steps beyond the traditional (steady state) models such as ISC and AERMOD. CALPPUFF allows users to select several species (polluting substances) simultaneously and build an output database of those contaminants.
This model treats the atmosphere in a more realistic fashion:
one that has many independent layers rather than just one. Each has its own stability, turbulence and wind characteristics for one thing.
Equally as important, this model treats an emission parcel as a puff. That means the transport that occurs during a particular time increment in the meteorological data file, typically an hour, uses the end point of the previous hour as its own starting point.
Again, this treatment is far more realistic than the steady state prediction, where each hour the effluent stream is transported under the initial conditions ad infinitum. Until ground impact or advection (transport) off of the modelling domain.
CALPUFF also handles deposition (with and without the help of precipitation) more realistically. This model contains a suite of algorithms for handling other long-range long-term effects, such as chemical transformations after initial release. CALPUFF handles terrain impact more precisely than earlier models.
If you`re interested in the subject, it`s worth learning more about this model. Search
this website for more model information now.