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

Final Report — September 2004
change substantially when data from one or both of the other sites were averaged with the
K-Bar data, so the analysis was continued using data from K-Bar only.
The time period evaluated is September 17 through October 28. Releases of PDCB
and PTCH were begun at San Antonio and Houston on Sept. 17. Tracer release of PTCH
from Houston was stopped on Oct. 25. Emissions for the other three sites continued until
Nov. 1, but release of ocPDCH from Eagle Pass became erratic after Oct. 28. A constant
release of tracers throughout this time period would have been ideal for TrMB analysis. This
was not the case during the BRAVO Study, which will contribute to some error in TrMB
results.
Table 9-6 is a summary of the results of this analysis. TrMB applied with several
trajectory model and wind field combinations is able to reproduce the known attributions of
all three tracers (given in the top part of the table) to within the error in the measured
concentration and the standard errors of the regression coefficients. The combinations
Table 9-6. Results of TrMB attribution of the tracer material that arrived at K-Bar from 9/17
to 10/28/99. The row above the double line gives the percent of the total measured
concentration due to each tracer. The remaining rows give the modeled percent
attributions for several combinations of back-trajectory model, input meteorological data,
and trajectory lengths. Attributions that are accurate within the uncertainty of the
measurement and standard error of the regression coefficients are shown in bold red type.
ocPDCH
Eagle Pass
PTCH
San Antonio
PDCB
Houston
Tracer Measurements
Mean Concentration (ppq) 6.52±0.99 23.47±3.39 2.62±0.33
Mean percentage of total tracer 20±4 72±13 8±1
Attributions of Tracer Material Arriving at K-Bar (%)
ATAD Raw 5-day 35 ± 12 65 ± 14 0 ± 9 0.495
ATAD EDAS/FNL 5-day 16 ± 8 33 ± 9 51 ± 9 0.708
HYSPLIT EDAS/FNL 5-day 28 ± 12 67 ± 13 5 ± 9 0.640
7-day 29 ± 13 68 ± 15 3 ± 11 0.603
10-day 27 ± 13 73 ± 16 0 ± 11 0.612
Monte Carlo EDAS/FNL 5-day 30 ± 9 43 ± 10 27 ± 8 0.721
7-day 33 ± 10 50 ± 10 18 ± 8 0.643
10-day 30 ± 9 39 ± 10 31 ± 8 0.689
ATAD MM5 5-day 34 ± 12 60 ± 13 6 ± 9 0.564
HYSPLIT MM5 5-day 82 ± 18 18 ± 18 0 ± 11 0.484
7-day 81 ± 18 19 ± 19 0 ± 11 0.489
10-day 81 ± 18 19 ± 18 0 ± 12 0.502
Monte Carlo MM5 5-day 23 ± 16 77 ± 19 0 ± 12 0.643
7-day 26 ± 17 74 ± 21 0 ± 13 0.616
10-day 24 ± 17 76 ± 21 0 ± 14 0.626
R 2
9-19