Modeling SF{sub 6} plume dispersion in complex terrain and meteorology with a limited data set

Comparison of ARAC calculations with surface and airborne measurements for the ACE field trials

“…Three different tracers (sulfur hexaflouride and two particulate tracers) were released simultaneously for each experiment. This document extends the discussion found in Schalk (1996) by providing a brief summary of the sulfur hexaflouride (SF6) modeling results for three of the remaining four ACE trials (the tracer plume from the fifth trial was not located by the monitoring teams and provided no tracer measurements for model comparison). This summary is followed by a discussion of model results for the two particulate tracers which were co-released with SF6.…”

“…The wind flow patterns as a function of time and comparison of model results with surface and elevated SF6 measurements are described here for releases 1-3, while release 4 is described in detail in Schalk (1996).…”

“…During this release the aircraft was approximately over the truck location for only a single measurement (at 1719 UTC). As Schalk (1996) shows, the modeled plume failed to move far enough to the east to reflect either the 25 ppt SF6 truck measurement or corresponding aircraft measurements. The truck sample is however consistent with the SF6 "hot spots" apparently being measured at that time by the aircraft a few kilometers to the east, which recorded concentrations of 17 and 44 ppt interspersed with several plume misses (e.g.…”

“…Table 1 lists the four ACE releases for which ARAC model calculations have been generated. For a detailed description of the modeling methodology, general experiment parameters, and detailed comparison results for the SF6 tracer dispersed in release number four, the reader is referred to Schalk (1996). The following discussion first summarizes SF6 results corresponding to releases one through three by presenting depictions of the pertinent modeled surface and upper level wind patterns, contoured SF6 concentrations, and a discussion of the comparison between modeled and measured minimum SF6 detectable concentrations (10 ppt) for each of the three experiments.…”