Community Modeling and Analysis System

Speciation Tool

NEW for SPECIATE 5.2! S2S-Tool

U.S. EPA's SPECIATE-to-SMOKE Tool (S2S-Tool) generates GSPRO and GSCNV files that are used by SMOKE to generate gridded emissions for photochemical modeling. All profiles are in the U.S. EPA's SPECIATE database, and the type of GSPRO/GSCNV files generated by the S2S-Tool are dependent on the speciation methods employed for the desired modeling platform.

SPECIATE is a database of organic gas, particle, and mercury speciation profiles. These profiles provide greater specificity than what is needed for a chemical mechanism within a photochemical model. The S2S-Tool, and previously the Speciation Tool, bridges this gap and translates SPECIATE data into a format that is chemical mechanism specific. The S2S-Tool should be used with SPECIATE 5.2 and later versions of SPECIATE.

S2S-Tool is available from the EPA GitHub repository: with more information available here:


Speciation Tool Version 5.1 Features

  • NOTE: To use SPECIATE 5.2, please download the S2S-Tool described above
  • Creates chemical speciation profiles needed to convert emission inventory pollutants (e.g., VOC, PM2.5) to model species for air quality modeling (e.g., using CMAQ and CAMx)
  • Outputs the chemical speciation profiles in formats used by SMOKE (i.e., GSPRO and GSCNV files)
  • NEW! Includes chemical speciation data from the EPA SPECIATE 5.1 database
  • Includes VOC mechanism mappings for several gas-phase mechanisms, namely CB05, CB6, SAPRC07T, CRI and RACM2, as implemented in CMAQ and CAMx. See Table 1 of User's Guide for a complete list and details of supported chemical mechanisms.
  • VOC mechanism mappings consider volatility to determine whether each compound is mapped to reactive model species (e.g. CB6) or intermediate-volatility model species (IVOC) or non-volatile model species (NVOL)
  • Optionally maps IVOC and NVOL compounds to the CMAQ Volatility Basis Set (VBS) scheme
  • Includes mappings of primary PM2.5 and PM10 to the CMAQ (AE6 and AE7) and CAMx (CF2) aerosol schemes
  • Create CMAQ AE6 speciation profiles from raw PM2.5 profiles in SPECIATE
  • Please check out the Speciation Tool Git Repository for more details

This is the official Speciation Tool website hosted by the Center for Environmental Modeling for Policy Development (CEMPD) at the University of North Carolina at Chapel Hill. The Speciation Tool is an active open-source development project developed by the Ramboll, and distributed by the Community Modeling and Analysis System Center.