CALPUFF View – Choosing Pollutants
March 2018
Last month, we reviewed AERMOD’s pollutant type selection which is natively limited to a single pollutant per model run. The CALPUFF model, on the other hand, is capable of modeling multiple pollutants at a time and includes chemical transformations.
In CALPUFF View selection of pollutants to model is done via the CALPUFF | Species & Deposition settings.
In CALPUFF View selection of pollutants to model is done via the CALPUFF | Species & Deposition settings.
CALPUFF View’s Species & Deposition Window
There are several components involved in the species selection.
Species Library
A default species library (species.lib) accompanies the application. This library includes dry and wet deposition parameters for 21 gas-based species and 25 particle species as well as parent and child ratios for 23 radiological decay species. Depositional parameters for the gases and particles can be modified using the Edit button. Modelers can also supply their own custom species library, if desired.
Modeled Species
The left-hand panel lists the species that will be modeled. Modelers can select their own pollutants or use the provided drop-down list to quick-select standard species for CALPUFF’s integrated chemical transformation schemes. Schemes include:
Modelers can also choose to add additional species to the pre-defined lists. Note that not all defined pollutants must be emitted by sources, but placeholder species are required for the selected chemical transformation process. When modeling the MESOPUFF II scheme, for example, SO4 and NO3 may not be directly emitted but will be formed by the model during its processing.
Also, the specific order of species is important to the model. The Aarow buttons can be used to maintain that order.
Species List
The list of available species is displayed on the right-hand panel. Multiple species can be selected using the Ctrl key. Use the Add button to add the selected species to the Modeled Species list. The Replace button can be used to replace an existing species with a different one without losing any emission rates already defined in the project.
Chemical Transformation
Species Library
A default species library (species.lib) accompanies the application. This library includes dry and wet deposition parameters for 21 gas-based species and 25 particle species as well as parent and child ratios for 23 radiological decay species. Depositional parameters for the gases and particles can be modified using the Edit button. Modelers can also supply their own custom species library, if desired.
Modeled Species
The left-hand panel lists the species that will be modeled. Modelers can select their own pollutants or use the provided drop-down list to quick-select standard species for CALPUFF’s integrated chemical transformation schemes. Schemes include:
- MESOPUFF II: Pseudo-first-order chemical reaction mechanism for conversion of SO2 to SO4 and total NOx to NO3.
- RIVAD: Treats the NO & NO2 conversion process in addition to the NO2 to total NO3 and SO2 to SO4 conversions.
- Secondary Organic Aerosols (SOA): Simulates transformations of aromatic compounds, biogenic hydrocarbons, and relevant mixtures in yielding organic aerosol.
- Fog: Modeling for visible plumes.
- Nuclear Decay: Models radiological decay rates of species defined in the default library.
Modelers can also choose to add additional species to the pre-defined lists. Note that not all defined pollutants must be emitted by sources, but placeholder species are required for the selected chemical transformation process. When modeling the MESOPUFF II scheme, for example, SO4 and NO3 may not be directly emitted but will be formed by the model during its processing.
Also, the specific order of species is important to the model. The Aarow buttons can be used to maintain that order.
Species List
The list of available species is displayed on the right-hand panel. Multiple species can be selected using the Ctrl key. Use the Add button to add the selected species to the Modeled Species list. The Replace button can be used to replace an existing species with a different one without losing any emission rates already defined in the project.
Chemical Transformation
CALPUFF View’s Chemical Transformation Window – MESOPUFF II Method
The Chemical Transformation window is used in concert with the Species & Deposition selections to define the transformation method and any associated information such as conversion rates, background concentrations, and monthly ozone / ammonia / SOA / H2O2 values.
