For any modeling effort, the emissions base year and future year are key modeling parameters needed for performing emissions processing. The base year is usually the year for which the air quality model is being run in order to compare modeling results with observed air quality data. Such comparisons allow modelers to tune the emissions data and air quality model, to ensure that the AQM is performing adequately during the modeling episode.
The base year is most often a year for which an emission inventory is available. This is usually the same year for which the meteorology model has been run to prepare input to SMOKE and an AQM and for which air quality observations are available. Of course there are exceptions to this principle, but generally that is how one establishes a base year.
Several different files and settings are used to set the base year in SMOKE, each of which should be consistent with each other for ideal results.
The YEAR setting in the SMOKE Assigns file is the reference point used by the scripts to determine the base year and set the names of various year-specific input files.
The episode and run settings (see Section 2.6.3, “Modeling episodes”) determine the base year that will be used in the model-ready output files. This base year must match the YEAR setting so that the correct input files are used.
The input emissions files should ideally contain data for the same base year, and the #YEAR header setting in those files should be consistent with the YEAR environment variable in the Assigns file. If the years in the annual inventory files are not consistent with each other, SMOKE will determine the year used by the most sources and set that as the base year. If day-specific or hour-specific data are used, all years in those files must be consistent with the base year of the annual emissions.
The MOBILE6 input data, if they are being used, should also be consistent with the base year. SMOKE is capable of running MOBILE6 with inputs from a different year, but certain inputs may not be correct.
Finally, the dates in the I/O API meteorology data from the Meteorology-Chemistry Interface Processor (MCIP) must be consistent with both the base year and the episode and run settings.
The future (or past) year is a chosen year in the future (or past) for which a modeler needs to run an air quality model; for example, to model the future effects of particular emission control strategies. To model a future year with SMOKE, you must have either an inventory that has been computed for a future year, or growth and control factors to project the base-year inventory to the future year. The settings and files that must be considered are as follows:
The setting FYEAR is set in the run script and is used by the script to automatically assign the name of the Cntlmat input file GCNTL, which contains the growth factors. FYEAR must be set to the future year even if a future-year inventory is not being created because it has already been provided to you.
If you already have a future-year inventory and so do not need to use SMOKE to project one from the base year inventory, then the emissions data year must match the future year, and the #YEAR header in the inventory file must match that year as well. In this case, the SMK_BASEYR_OVERRIDE setting must also be used to indicate what the base year is (which will be the same as the year of the meteorology data).
The MOBILE6 input data, if they are being used, must also include the correct settings for the future year of interest.
The episode and run settings, meteorology files, and day- or hour-specific inventories should not match the future year, but rather should use the base-year episode dates.