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The Texas Commission on
Environmental Quality (TCEQ)
has implemented emissions processing methods for building Texas emissions
inventory used for the Houston-Galveston Area state implementation
plan modeling studies. In
particular, the inventory data, which include Houston-Galveston Ship Channel
point-source speciated VOC emissions, are processed through the EPS2 (Emissions
Preprocessing System Version 2) system, GloBEIS3, and EPA’s MOBILE6 modified by the Texas Transportation
Institute. The emissions data are used with the CAMx air quality model to
assess the efficacy of the emissions control strategies in the HGA. As an alternative
modeling tool, EPA’s Community Multiscale Air Quality (CMAQ) modeling system,
which includes the Sparse Matrix Operator Kernel Emissions (SMOKE) emissions
processing system (Coats et al, 1995 and Benjey et al., 2001), is expected to
gain more acceptance for air quality studies and eventually for the SIP
process. To evaluate effects of
different physical and chemical processes on air quality, up-to-date Texas emissions
data must be used. However, the current
Texas EI data format and processing steps are tightly linked with the EPS2
system.
While
the system has proven its capability providing necessary emissions input for
CAMx operated by TCEQ, external organizations or university researchers have
been unable to test emissions scenarios because they could not generate
necessary model-ready emissions data for other air quality models. One of the key scientific benefits of using the SMOKE
system over EPS2 is that it allows easy extension of the chemical mechanisms
permitting investigation of the effects of the specific chemical components (e.g., highly reactive C2-C4 olefin species) on ozone production. With some additional effort, the SMOKE system can be extended to include
speciated particulate emissions and air toxic species. The computational benefits of the SMOKE
system include the ability to process emissions much faster than other systems, to minimize redundant data storage for decreased
file sizes, and to provide outputs for the CMAQ modeling system (Byun and
Ching, 1999) and CAMx. Coupled with the
SMOKE Tool which processes emission shape files for area and mobile sources,
SMOKE is a more integrated system than EPS2 and more user-friendly.
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