Current Project Information Page

Development of an Improved Chemical Speciation Database for Processing Emissions of Volatile Organic Compounds for Air Quality Models

William P. L. Carter
College of Engineering, Center for Environmental Research and Technology (CE-CERT)
University of California, Riverside, CA 92521

Database last updated March 9, 2023
Programs or input files last updated November 20, 2014
Page last updated March 9, 2023


This database gives model species assignments for various chemical mechanisms for for use with various emissions profile database for organic compounds emitted into the atmosphere. This database can be used to assign model species in (currently) 15 different chemical mechanisms to total organic gas (TOG) speciation profiles in 5 different profile databases. A manuscript describing the database and its assignments for various emissions and profile databases has been published in the Journal of the Air & Waste Management Association (W. P. L. Carter, "Development of a database for chemical mechanism assignments for volatile organic emissions," J. Air & Waste Management Association, Volume 65, Issue 10, pages 1171-1184, 2015, DOI: 10.1080/10962247.2015.1013646) and is also available upon request. A users manual also describing this database and associated programs and files and discussing how to install and use them is available here. The assignments are incorporated in two Excel spreadsheets, one of which has macros to output the assignments in files for use with existing speciation processing systems. Fortran programs were developed to use the assignments to make GSPRO files for SMOKE, and files output by the system can be imported directly into the Speciation Tool. Developing these assignments required creating a unified organic compound and mixture classification system, assigning compounds to mixtures, assigning model species to compounds for the various mechanisms, and developing procedures for processing these assignments and also making assignments for unknown, unassigned, or nonvolatile mass. The database files and associated programs and documentation can be downloaded from this location. 

In addition, ozone reactivity values in the MIR, MOIR, and EBIR scales have been estimated for all the gas-phase organic speciation profiles in the Speciate 4.3 database. These include upper, lower, and best-estimate reactivity estimates in each scale. The report consists of a document (Speciate-Reactivity.pdf) describing the objectives and methodology employed and a spreadsheet (Speciate-Reactivity-Appendix.xls) containing the tables with the results. The report is dated November 21, 2013.

Note that the database structure and associated programs and documentation were revised and made available on 2/10/14. See the web page for the previous version for a discussion of the previous version of the database and the programs and a list of updates prior to that date.

What's New (updates after 2015)
Documentation and Database files
  • SpecDB.pdf (Dated January 21, 2015): Documentation and users manual for the current database and files
  • (March 9, 2023): All files and programs discussed in SpecDB.pdf. (Note that these do not contain the SAPRC-16 and MOZART assignments)
  • SpecDB.xls (March 9, 2023): Spreadsheet with speciation assignments and macros to output files for speciation processing by SMOKE and the Speciation Tool
  • MechDB.xls (March 9, 2023): Spreadsheet listing model species and related information for the supported mechanisms. Needed by the macros in SpecDB.xls.

Update History
  • Added and then updated assignments for a preliminary version of SAPRC-22. More information about that version will be available when the mechanism is finalized.
  • Added assignments for a preliminary version of SAPRC-18, an update to SAPRC-16. This will be superceded by SAPRC-22.
  • Added assignments assignments for the SAPRC-16 mechanims, a major update to the SAPRC mechanisms. This will be superceded by SAPRC-22.
  • Assignments have been added by the MOZART-T1 mechanism.  These were made by Geoff Tyndall, John Orlando and Christoph Knote and provided by Christoph Knote on 8/17/15.
  • A few assignments to NROG or NVOL were made for compounds assigned for MOZART that weren't previously assigned for other mechanisms.
  • Updated the users manual document to include an improved discussion of how to install the files and test the installation and how to add new mechanisms or support for additional profile databases.
  • Updated the documentation sheet to be more constent with the currrent database.
  • Deleted mechanisms that are still under development or whose assignmets are incomplete.
  • Made various corrections to assignments and categories
  • Added new categories and compounds found in Speciate 4.4.
  • Added Smiles strings for many compounds and a few new CAS numbers using the SmileCas database.
  • Added CO as an explicit species for all mechanisms. Was previously assigned as unreactive.
  • Renamed some SAPRC07 model species to be consistent with emissions surrogate names currently used in CMAQ.
  • Added BENZENE and SESQ to CB05, since these are used for SOA modeling for CB05 in CMAQ.
  • Redid category numbers for uncertain mixture categories and changed assignments categories refering to salts, elements, and PM to nonvolatile.
  • Model species for SAPRC-99 and SAPRC-07T changed to be consistent with implementation of these mechanisms in CMAQ. Note that this means that SAPRC-99 now has separate model species for benzene and sesquiterpenes.
  • Programs and macros changed to allow for more than 8-character model species names (except for Carbon Bond-type mechanisms).
  • Format of GSPRO files output by SpecDB.xls and ProfAsn.exe changed from fixed width to CSV.
  • Macro to output BEIS 3 emissions replaced by a general GSPRO output macro. (The previous macro did not output NROG in mass units.)
  • Assignments for BEIS 3 biogenic emissions categories updated and macros to output GSPRO for BEIS3 has been added.
  • MEGAN 2.1 biogenic emissions assignmnets for the 18 biogenic VOC categories
  • A number of biogenic VOCs have been added to the list of compounds
  • Preliminary model species assignments have been made for BEIS 3 biogenic organic emissions categories. These are subject to change.
  • SAPRC-11D model species added for cis-3-hexen-1-ol and cis-3-hexenyl acetate.

Related links
  • Current SAPRC Mechanism page ( This has links to SAPRC reactivity scales and to files and programs for implemeting SAPRC mechanisms and the SAPRC box and chamber modeling software.

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