The Layalloc program calculates 3-D emissions from a 2-D pre-gridded emissions file. Layalloc is used to reallocate single layer 2-D surface layer emissions into multiple model layers. This approach is useful for processing pre-gridded or industrial area source inventories that do not contain stack information for plume rise treatment but represent elevated sources.

Layalloc reads in a gridded 2-D pre-gridded emissions file (either output from the Smkmerge program or from a pregridded global emission inventory (EDGAR/RCP/HTAP)) and redistributes the emissions into multiple model layers based on a user-defined vertical profile. The vertical profiles that are input to Layalloc consist of a layer bottom height, layer top height, and the fraction of emissions to allocate to the layer. SMOKE willl interpolate from the layer heights (in meters) to the model layers (in sigma-pressure). This approach assumes that the vertical factors are uniformly applied over all horizontal grid cells. The resulting hourly, gridded, speciated 3-D emissions data are output to a new I/O API file with the same temporal resolution and the same model species as the original 2-D emissions file.

This optional program can be run after Smkmerge and before either Mrggrid (if it is being used to merge several Smkmerge output files together) or the AQM of interest.