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

Final Report — September 2004
REMSAD simulates this initial plume rise. Tracer releases at the other two locations were
released directly in the ambient air and thus did not have any plume rise. An example of a
REMSAD simulation of the transport and dispersion of the four tracers is illustrated in
Figure 9-13.
Figure 9-13. Example of the
REMSAD-simulated dispersion of
the four tracer plumes on 28
September 1999. The colored
areas in this 3-dimensional view
of the REMSAD modeling
domain represent concentrations
above 0.1 ppq. The wind is
generally toward the north, so the
southern ends of the colored
regions are in the vicinity of the
release locations. The plumes
represent the tracer released
from (from left to right across the
bottom) Eagle Pass, San
Antonio, Houston and (the green
area) northeast Texas.
Because of the coarse grid scale of the model and the complex topography in the Big
Bend region, both modeled estimates and measured tracer concentrations were averaged over
all three measurement sites in Big Bend National Park. (San Vicente, K-Bar, and Persimmon
Gap). These three-site averages of 24-hr measurements and modeled estimates are compared
for each tracer in Figures 9-14 through 9-17. Results for the Eagle Pass and northeast Texas
tracers are shown for the entire four month BRAVO period, while results for the San Antonio
and Houston tracers are shown for those last six weeks of the BRAVO period when the
tracers were released from these sites. Note that the vertical scales of these figures are not all
the same. The “mixing ratio” is equivalent to the tracer concentration in ppq by volume.
Performance statistics corresponding to these figures are tabulated in Table 9-11.
9-35