Home Page:  Speciation Profiles Used in ARB Modeling

This page last reviewed December 12, 2012


This is the HOME page for access to the speciation data used by the ARB in its various emissions modeling programs.  Please read this page, before navigating the site using the SPECIATION links column at the left of this page.

Speciation profiles provide estimates of the chemical composition of emissions, and are used in the emission inventory and air quality models. ARB maintains and updates estimates of the chemical composition and size fractions of particulate matter (PM) and the chemical composition and reactive fractions of total organic gases (TOG), for a variety of emission source categories. 

From the SPECIATION links column to the left, you can choose the INTERACTIVE OPTION, which allows the scanning, printing and download of all or selected portions of data files.  The interactive option allows you to search/filter on a variety of data fields. You can also choose the DOWNLOAD OPTION, to simply download selected data files. 

There are multiple "versions" of the speciation profiles that are available both from the DOWNLOAD OPTION and the INTERACTIVE OPTION. A version refers to a complete set of speciation profile tables, which is frozen at a particular time. The version may be a default version (also referred to as a "main" version) , or it may be specific to a particular modeling/inventory use. The versions can be selected from tables accessible from the DOWNLOAD OPTION and INTERACTIVE OPTION pages. Once a profile version has been selected, it will remain selected regardless of where you navigate within this speciation website. The main tracking identification for the versions is termed a "version ID." The version ID numbers start at 10000, and increment up by one as new versions are added to the database. . 

The DOWNLOAD OPTION is included here since there are some data that are not included in the interactive files. The DOWNLOAD OPTION files use slightly different terms and data breakdowns than does the INTERACTIVE OPTION portion of this web site.  Be sure you understand the differences between the two approaches, before attempting to combine data from the two approaches.  You are probably best to work with one approach or the other, at least until you are familiar with the two sets of data.

The SPECIATION links column at the left of this page also provides background information describing how the speciation data were developed, what the terms used in conjunction with the data mean, and how the data can be used to calculate single compound concentrations from nonspeciated total organic gas (TOG) or particulate matter (PM) emission estimates. The WHAT'S NEW  link allows you to see recent changes to the speciation profiles. The USING DATA link shows example calculations.  The SOURCE CODES link explains how the SCC and/or EIC codes are assigned to the speciation profiles.  These SCC and/or EIC codes are also assigned to the emission inventory, providing the link between the emissions and the speciation profiles.  

The DEFINITIONS link explains terms used to describe the profiles and their chemical groupings.  The REFERENCES link allows access to consolidated listings of the references used for the speciation profiles.  The references can also be accessed, through the profiles that use them, using the INTERACTIVE OPTION portion of this web site.

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