6.4. Grdmat

6.4.1. Description
6.4.2. Processing Order
6.4.3. Files and Environment Variables

6.4.1. Description

Processing categories: area, mobile, point

The Grdmat program produces the matrix that contains the factors for spatially allocating the emission sources to the modeling domain.

For pre-gridded inventory data, grdmat is used to convert the data from the input data grid (e.g. lat-lon for EDGAR/RCP/HTAP) to the output modeling grid when the user sets IMPORT_GRDNETCDF_YN to Y. Spatial surrogates (AGPRO or MGPRO) are not needed for processing gridded inventory data with SMOKE. The input modeling domain information is obtained from the GRIDMASK input file and the output grid is defined by the IOAPI_GRIDNAME_1 environment variable in the GRID_CRO_2D file.

For inventory data that is not already pre-gridded, point sources are assigned to grid cells using the geographic coordinates that are stored in each point-source record. For area and mobile sources, a cross-reference file matches the gridding surrogates to the source-level emissions. When the gridding cross-reference files are applied, the most-specific matches always override the less-specific ones.

For the current version of SMOKE, a gridding surrogates file must be created for the specific grid of interest. This can be accomplished in a variety of ways:

  • ArcInfo (or other GIS) processing by an expert in creating gridding surrogates.

  • Using the MIMS Spatial Allocation Tool.

  • Extracting surrogate data from a larger gridding surrogates file. National 4-km surrogates are available from the EPA at http://www.epa.gov/ttn/chief/emch/spatial/newsurrogate.html. To use these data for your modeling, you must use the same grid projection as was used to create the gridding surrogates.

For area sources, the gridding cross-reference file provides the following possible combinations, ordered from most specific to least specific:

  1. Country/state/county code and 10-digit SCC

  2. Country/state/county code and 7-digit SCC

  3. Country/state code and 10-digit SCC

  4. Country/state code and 7-digit SCC

  5. 10-digit SCC

  6. 7-digit SCC

  7. Country/state/county code

  8. Country/state code

  9. Ultimate default (country/state/county code = 0, SCC = 0)

For mobile sources, the available combinations and their order are:

  1. Country/state/county code, and 10-digit SCC

  2. Country/state code and 10-digit SCC

  3. Country/state/county code

  4. Country/state code

  5. 10-digit SCC

  6. Ultimate default (country/state/county code = 0, SCC = 0)