The purpose of SMOKE is to convert the resolution of the data in an emission inventory to the resolution needed by an air quality model. Emission inventories typically have an annual-total emissions value for each emissions source, or perhaps an average-day emissions value. The AQMs, however, typically require emissions data on an hourly basis, for each model grid cell (and perhaps model layer), and for each model species. Consequently, to achieve the input requirements of the AQM, emissions processing must (at a minimum) transform inventory data by temporal allocation, chemical speciation, spatial allocation, and perhaps layer assignment.

In addition to changing the resolution of the data, SMOKE must also provide the AQM input files in the correct file format. SMOKE can create the Input/Output Applications Programming Interface (I/O API) Network Common Data Form (NetCDF) output format needed by the CMAQ model. It can also create the Fortran binary format for the 2-D emissions needed by UAM, and CAM_X, and the ASCII elevated-point-source format used by the Ptsrce preprocessor to these models. File format is also important for the input files used by SMOKE, most of which are ASCII files, but some of which are I/O API NetCDF or CF-compliant NetCDF format files.

In this chapter, we introduce you to various concepts that are critical to understanding the technical description of emissions processing, as well as provide more detail about the processing capabilities of SMOKE. (Later, Chapter 3, SMOKE Utility Tools, Chapter 4, SMOKE Core Programs, Chapter 5, SMOKE Quality Assurance, Chapter 6, SMOKE Input Files, Chapter 7, SMOKE Intermediate Files, and Chapter 8, SMOKE Output Files give more specifics about each program’s capabilities and each file’s format.) This chapter provides the context and framework for the rest of the user’s manual. To assist you in reading and using this chapter, we provide Appendix A. Glossary for definitions of emissions inventory and emissions modeling terminology.