CMU Ammonia Emission Inventory for the Continental United States

Cliff Davidson
Peter Adams
Ross Strader
Rob Pinder
Natalie Anderson
Marian Goebes
Josh Ayers

Numerous computer models have been developed to predict airborne particle concentrations given source emissions and meteorology data as inputs. The models have become somewhat sophisticated, with high-resolution outputs, although the accuracy of the predictions from these models is only as good as the quality of the input data. The quality of the meteorological data is generally good, as is the quality of source emissions data for regulated species such as sulfur oxides and nitrogen oxides. However, there are some chemical species that are not federally regulated and thus emissions data are far less abundant. One such species is ammonia, which plays a major role in the formation of airborne particles. Knowledge of ammonia emissions is important in that an accurate characterization of airborne ammonia concentrations is vital to the choice of control strategies.

Cliff Davidson's research group has developed a software application that generates an ammonia emission inventory for the continental United States based on user- defined input. Emission factors and activity levels are kept in easily modifiable input files. This structure makes it easy to perform sensitivity analyses and to update the inventory when new data become available.

Version 3 of the CMU Ammonia Model has been completely rewritten in order to add several new features. Among these new features are:

  • the model now has a graphical user interface in the form of a windows application that makes it much easier to run; the user no longer has to edit ASCII text files to change run parameters
  • the user can choose which states and sources to include in the model run
  • the model now permits the use of monthly resolution for all sources, for both activity levels and emission factors. This will enable the model to take advantage of new work currently underway at CMU to estimate emission factors for dairy cattle that are county and month specific
  • there are now several different choices for output, including NIF 3.0 formatted output, GIS ready output, and summary tables that permit easy viewing of the results.
  • the default emission factor dataset included with the model has been updated
To download the model, please click here.

The Environmental Institute