(BRAVO) Study: Final Report. - Desert Research Institute

Final Report — September 2004
Table 9-10. Source attribution estimates from application of the FMBR method using a set of
REMSAD-predicted sulfate concentrations, and comparison with a sample set of REMSAD source
attributions. Results are shown for three trajectory lengths. Estimated attributions within one
standard error of the REMSAD results are in bold, red type.
SOURCE REGIONS
FMBR % Contribution ± Standard Error
5 day 7 day 10 day *REMSAD Model
Carbón Plant 16.1 ± 4.2 16.5 ± 4.1 15.4 ± 4.2 14.1
Rest of Mexico 13.6 ± 9.6 12.2 ± 10.2 11.6 ± 11.1 10.0
NE Texas 7.8 ± 2.8 9.5 ± 3.0 10.2 ± 3.1 5.4
SE Texas 14.0 ± 4.1 11.9 ± 4.3 11.8 ± 4.6 8.8
Rest of Texas 5.0 ± 4.2 4.0 ± 4.5 3.7 ± 4.8 2.3
LA/MS & MO/IL/AR 33.8 ± 5.6 28.7 ± 7.6 27.6 ± 8.2 22.3
East Central U.S. 0.6 ± 2.1 7.4 ± 4.4 8.8 ± 4.8 13.6
Rest of Eastern U.S. 2.1 ± 2.9 2.7 ± 4.1 4.0 ± 5.1 7.4
Western U.S. 0.0 ± 7.8 0. 0± 8.5 0.0 ± 9.3 9.3
Boundary Conditions 7 7 7 7.2
AGGREGATED REGIONS
Mexico (all) 29.6 ± 10.4 28.8 ± 11.0 27.0 ± 11.8 24.0
Texas (all) 26.8 ± 6.5 25.4 ± 7.0 25.7 ± 7.3 16.5
Eastern U.S. (all) 36.5 ± 6.7 38.8 ± 9.7 40.4 ± 10.8 43.2
Western U.S. (all) 0. 0± 7.8 0.0 ± 8.5 0.0 ± 9.3 9.3
Boundary Conditions 7 7 7 7.2
* REMSAD source attributions were increased by 2.7% to account for missing mass due to nonlinearities in the
apportionment simulations. Note that these attributions are a sample set and do not necessarily represent the findings of
the BRAVO Study, which are presented in Chapter 11.
The FMBR-estimated daily concentrations of sulfate over each of the source regions
compared favorably with the REMSAD sulfate data, with r 2 about 0.8, an RMS error of 40%,
and bias of 4%. Consequently, the sulfur transport from 10 large source regions, multiplied
by a constant, explains 80% of the variance in the REMSAD sulfate daily time series.
The percentages of sulfate attributed by the FMBR approach to each of the source
regions, and for larger aggregate regions, are presented in Table 9-10 for three different
lengths – 5, 7, and 10 days – of the simulated source plumes. REMSAD attributions for the
same source regions are shown for comparison. Each FMBR value is followed by its
standard error; apportionments within one standard error of the REMSAD values are shown
in bold red type. The boundary conditions accounted for about 7% of the total REMSAD
simulated sulfate at Big Bend, which is included in all columns. (Note that the attributions in
Table 9-10 are not the final REMSAD attributions developed by this study, but rather an
earlier set of REMSAD results that provide an artificial reality for evaluating the
performance of the FMBR method. The actual attribution results of the BRAVO Study will
be presented in Chapters 10 and 11.)
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