4. Spatial Surrogates
As described in the introduction, Spatial surrogates are most commonly used to map state- or county- level emissions data onto the rectangular grid cells used by an Eulerian air quality model such as the CMAQ modeling system.
Surrogate Tools are used to create and process spatial surrogates used to allocate county-level emissions to grid cells. The Java-based Surrogate tool program was designed to simplify the process of generating dozens of surrogates and to provide clear documentation about how each surrogate is created. For each surrogate it calculates, the Surrogate tool generates documentation that includes the shapefiles and attributes used in the computations, whether the surrogate was created by merging other surrogates, and which surrogates were used for gap-filling. The Surrogate tool program takes input information from five comma-separated-value (.csv) files and a grid description file. The QA tool summarizes quality assurance information for computed surrogates.The Normalization tool is used to normalize a set of surrogates (i.e., make them sum to approximately 1.0). All java programs are packed into the SurrogateTools.jar file.
More information on the SurrogateTools is available at
http://www.ie.unc.edu/cempd/projects/mims/spatial/srgtool/SurrogateToolUserGuide.v3.6.htm
To Section 4.1: Generating Surrogates from Weight Shapefiles