4.4.10. Use a different speciation mechanism or change speciation inputs

4.4.10.1. Choosing from default mechanisms
4.4.10.2. Setup of new mechanism or changing an existing mechanism
4.4.10.3. Changing speciation assignments
4.4.10.4. Changing the definition of NONHAPVOC or NONHAPTOG

A common change to the SMOKE configuration is to select a speciation approach for an air quality model and chemical mechanism. In Chapter 4, How to Use SMOKE, we noted that many speciation files are available for download from EPA. In this section, we describe how to use the SPC value in the Assigns file to select these.

4.4.10.1. Choosing from default mechanisms

SMOKE provides several chemical mechanisms that one can select for modeling. In the default SMOKE configuration, only a few small changes are necessary to the Assigns file and script to use a different chemical mechanism.

  1. Set the SPC setting in the Assigns file.

    The SPC setting in the Assigns file controls which chemical mechanism is used by the scripts and SMOKE programs. Depending on what source categories you are modeling, the air quality model that you are using, and the chemical mechanism for that air quality model. See the default data files described in Chapter 4, How to Use SMOKE for the actual file names that will be used for each source category. Where different files are needed for different source categories, the Assigns file will automatically detect this and set the GSPRO and GSREF files accordingly.

  2. Determine whether VOC-to-TOG or ROG-to-TOG is needed and set script accordingly.

    If your inventory contains the pollutant VOC or ROG and you are modeling for CMAQ, UAM, or CAMX, then you will need to use SMOKE’s GSCNV file to convert the VOC or ROG mass to TOG mass.

    The SMOKE Spcmat program will use the GSCNV file if the POLLUTANT_CONVERSION setting in the script is Y. This is the default configuration for the CMAQ run scripts.

    If your inventory contains TOG, then the POLLUTANT_CONVERSION setting in the run script should be set to N.

  3. Ensure that the inventory pollutants that need speciation match the inventory pollutants in the speciation profiles and cross-reference files.

    All of the pollutants in your inventory that you wish to include in the outputs must have valid profiles in the GSPRO and GSREF files. If the pollutant is left out of the GSREF file, the pollutant will be dropped from modeling (in some cases, this is desirable, but a warning will be generated by Spcmat). For each pollutant in your inventory check that:

    1. The pollutant has one or more entries in the GSREF file. In some cases, you may have to add entries. For example, not all GSREF files have “ROG” entries, but these can easily be added simply by copying the VOC assignments and changing the VOC label to ROG.

    2. For CMAQ, UAM, and CAMX and the pollutant is VOC or ROG, check that the TOG profiles are in the GSPRO file.

    3. For all models and all other pollutants, check that the profiles are included in the GSPRO file.

  4. Ensure that the correct Assigns file is used in your run scripts.

4.4.10.2. Setup of new mechanism or changing an existing mechanism

  1. Create and install the GSPRO file.

    If only a few changes will be made to a GSPRO file, you can simply copy an existing GSPRO file to a new file. If more extensive changes are needed to create a new mechanism, currently, there is no utility for creating a GSPRO file in SMOKE. For now, users must use the file format in Chapter 8, SMOKE Input Files and a high degree of expertise to develop new GSPRO files.

    Install the GSPRO file in the $GE_DAT directory. For the default GSPRO file for that chemical mechanism (i.e., the one that applies to the most source categories), name the file gspro.$SPC.txt. If your speciation profile is specific to a certain source category, name the GSPRO file as follows:

    • area/non-road mobile: gspro.$SPC.a.txt

    • on-road mobile: gspro.$SPC.m.txt

    • point: gspro.$SPC.p.txt

  2. Create and install the GSREF file.

    You may be able to simply copy a GSREF file to a new name, depending on whether the profile codes are different for your new mechanism. In many cases, the same profile codes are used (e.g., from the SPECIATE database), but the profiles themselves are all that have changed.

    If you need to create a new GSREF from scratch, you will need to ensure that all of the SCCs and all of the pollutants in the inventory have profile assignments. Any pollutant in the inventory that is not included in the GSREF file will be dropped from modeling. Any SCC that is not included will be assigned the default profile, which is the profile assigned to SCC = 0.

    Name the GSREF file using a similar approach as for the GSPRO file, but use the “gsref” prefix instead of the “gspro” prefix. Therefore, the default file for that chemical mechanism (the one that applies to the most source categories) should be named gsref.$SPC.txt. Any source-category-specific files should use the names as follows:

    • area/non-road mobile: gsref.$SPC.a.txt

    • on-road mobile: gsref.$SPC.m.txt

    • point: gsref.$SPC.p.txt

  3. Create the pollutant-to-pollutant conversion file, if necessary.

    If the speciation profiles change or new profiles are added for VOC speciation, a GSCNV file must be created accordingly. This can be accomplished by copying and editing the example GSCNV file or creating a new GSCNV file from scratch. This requires a high degree of expertise and must be closely coordinated with creating the GSPRO file.

  4. Edit the INVTABLE file.

    Particularly for toxics modeling, changes to the GSPRO file must be coordinated with changes to the INVTABLE file in the following ways:

    • If the definition of NONHAPVOC changes, the INVTABLE definition of NONHAPVOC must change as well.

    • If there are new explicit model species, these must be identified in the INVTABLE file.

    • If there are new model species that are not part of the chemical mechanism, these must be identified in the INVTABLE file.

    • If there are new pollutants, these must be included in the INVTABLE file (as well as the raw inventories, of course).

  5. Coordinate with MOVES inputs.

    When processing using on-road mobile emissions and SMOKE running MOVES, users need to create the MEPROC file that contains a list of MOVES pollutants by emissions processes created by MOVES. This SMOKE input need to be coordinated so that the pollutants expected by the chemical mechanism are all created by SMOKE/MOVES. This requires that the MEPROC file have all pollutant/process combinations for the required pollutants and that the MOVES inputs are configured to generate emissions for those pollutants. The MEPROC file is documented in Section 8.9.2.1.3, “MEPROC: List of mobile emission processes and associated activities and pollutants”. The MOVES inputs are documented in the MOVES manual, and the limitations placed on these files by SMOKE are documented in Section 4.4.12, “Use MOVES for on-road mobile sources”.

  6. Edit the Assigns file and scripts

    Make sure to change the SPC variable in your Assigns file to the one for your new chemical mechanism. Also make sure that your run scripts use the Assigns file with the correct SPC setting.

4.4.10.3. Changing speciation assignments

Speciation assignments can be changed so that different speciation profiles are used for certain SCCs and pollutants or to add SCCs and pollutants. You will need to ensure that all of the SCCs and all of the pollutants in the inventory have profile assignments. Any pollutant in the inventory that is not included in the GSREF file will be dropped from modeling. Any SCC that is not included will be assigned the default profile, which is the profile assigned to SCC = 0.

  1. Adding entries to an existing cross-reference file.

    Edit an existing cross-reference file or copy it to a new file for editing. Insert the new speciation assignments based on the format of the file, described in Chapter 8, SMOKE Input Files.

  2. Create new speciation cross-reference file(s) for your case.

    Copy the speciation cross-reference (GSREF) file for the chemical mechanism that you are using (or a chemical mechanism that is most similar to the one you have created). Edit the speciation profile assignments using the file format, described in Chapter 8, SMOKE Input Files. The naming convention for the new file must be consistent with the convention described in the previous subsection.

  3. Change the pollutant-to-pollutant conversion file.

    If different SCCs get different profiles, then the GSCNV file must be changed as well. The VOC-to-TOG factor in the GSCNV depends on the profile that has been assigned to an SCC. So, the factor must be consistent with the profile assigned. Calculating the VOC-to-TOG factor requires some expertise, and this is outside the scope of this manual. However, if you change an SCC to use an existing profile, you can determine the correct VOC-to-TOG factor by first finding another SCC that uses that profile and then setting the VOC-to-TOG factor to be the same as the one for that other SCC.

  4. If any new files are created, ensure that the Assigns file uses all new files.

    Make sure that the SPC setting in the Assigns is correct and that the Assigns file will set the GSPRO, GSREF, and GSCNV files so that any new files will be used by the programs.

4.4.10.4. Changing the definition of NONHAPVOC or NONHAPTOG

The definition of NONHAPVOC and NONHAPTOG simply must be consistent between the GSPRO file and the INVTABLE file. This change applies only to chemical mechanisms that use VOC model species and can therefore benefit from the integration of toxics and criteria VOC. This includes all models that SMOKE supports.

  1. Edit the INVTABLE file.

    You can add pollutants and change their NONHAPVOC status using the INVTABLE file format provided in Chapter 8, SMOKE Input Files.

  2. Create new speciation profiles.

    The speciation profiles must use the same definition of NONHAPVOC or NONHAPTOG. The header of the file must be updated to reflect the new definitions. The profiles for NONHAPVOC and NONHAPTOG must also be updated to be consistent. Finally, all other TOG profiles must be updated to be consistent with the definition.

  3. Coordinate with MOVES inputs.

    When processing using on-road mobile emissions and SMOKE running MOVES, users need to create the MEPROC file that contains a list of MOVES pollutants by emissions processes created by MOVES. This SMOKE input need to be coordinated so that the pollutants expected by the chemical mechanism are all created by SMOKE/MOVES. This requires that the MEPROC file have all pollutant/process combinations for the required pollutants and that the MOVES inputs are configured to generate emissions for those pollutants. The MEPROC file is documented in Section 8.9.2.1.3, “MEPROC: List of mobile emission processes and associated activities and pollutants”. The MOVES inputs are documented in the MOVES manual, and the limitations placed on these files by SMOKE are documented in Section 4.4.12, “Use MOVES for on-road mobile sources”.