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.
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:
Country/state/county code and 10-digit SCC
Country/state/county code and 7-digit SCC
Country/state code and 10-digit SCC
Country/state code and 7-digit SCC
10-digit SCC
7-digit SCC
Country/state/county code
Country/state code
Ultimate default (country/state/county code = 0, SCC = 0)
For mobile sources, the available combinations and their order are:
Country/state/county code, and 10-digit SCC
Country/state code and 10-digit SCC
Country/state/county code
Country/state code
10-digit SCC
Ultimate default (country/state/county code = 0, SCC = 0)