CRC Report No. A-34 - Coordinating Research Council

April 2005
Sunday
3-Aug-97
Monday
4-Aug-97
Tuesday
5-Aug-97
Wednesday
6-Aug-97
Thursday
7-Aug-97
CO
On-road Mobile 6031.2 7015.6 7458.9 7277.2 6918.3
Other surface 2598.8 1157.4 1157.4 1157.4 1157.4
Point source 42.2 45.1 43.4 43.8 44.6
Wildfire 169.7 33.9 1825.7 9018.8 4058.2
Biogenic 0.0 0.0 0.0 0.0 0.0
Total 8841.9 8252.0 10485.4 17497.3 12178.6
Notes:
1. On-road mobile emissions are from EMFAC2001.
2. Other surface emissions include off-road mobile and area sources.
3. CB4-ROG is the sum of CB4 species assuming molecular weights of 16 per Carbon to account for
average carbon/hydrogen/oxygen ratios in VOC.
4. NOx includes HONO emissions.
Reactive Tracer Emission Inventories for PAMS Species
The ARB SCOS97 emissions inventory provides organic emissions as total organic gases
(TOG). The relationships between TOG and other definitions of organic gases are defined to
minimize confusion later on. Reactive organic gases (ROG, equivalent to the EPA term VOC)
are a subset of TOG that excludes methane, ethane, acetone, methyl acetate and many
halogenated compounds. The 55 PAMS species listed in Table 2-1 are a subset of ROG except
for ethane. Consequently:
• Emissions of TOG are always greater than ROG
• Emissions of ROG generally are greater than the sum of PAMS except when ethane is a
significant contributor.
The ARB SCOS97 emissions inventory classifies TOG emissions from thousands of source
categories that are identified by source category codes (SCCs). TOG emissions are chemical
speciated using speciation profiles that apportion TOG to individual organic compounds. The
ARB has a TOG speciation library containing hundreds of source profiles. Many speciation
profiles are assigned by the ARB to multiple SCCs. The SCOS97 emissions inventory was
analyzed to identify a manageable number (~20) of source category groupings that account for
most of the organic gas emissions. The source category groupings were selected to combine
emissions that have similar chemical speciation, or that receptor modelers generally assume can
be represented by a characteristic speciation profile.
The SCOS97 TOG emission data were the starting point for the selection of source categories to
be modeled. The emission inventory for August 5, 1997 contains 170 source categories with at
least 1 ton/day of TOG emissions (Appendix A, Table A-1). These 170 source categories
account for more than 96% of the total TOG emissions in the CAMx modeling domain and are
mapped to 86 different chemical speciation profiles (Appendix A, Table A-2). The 170 ARB
source categories were assigned to the 21 source category groups shown in Table 2-3. An
additional source category was included called “hypothetical industrial operations” as described
below. The top 20 speciation profiles with the highest ROG emissions (excluding wildfires) are
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