October 13, 2004
Dispersion studies in urban areas have classically made use of intentional releases of small quantities of easily-detected trace gases, typically sulfur hexafluoride (SF6). ARL’s Field Research Division in Idaho Falls has been a major player in all recent field studies using SF6. A classical problem has been that urban studies of this kind have been hindered by the background concentrations of SF6, arising from its widespread industrial use in electrical transformers.
Data from a January 2004 study in New York and Washington have cast this “problem” in a new light. Urban sources of SF6 can be easily identified. For example, there are two such sources in the near vicinity of the White House. Surveys of SF6 levels in the streets around the White House indicate the presence of SF6 from these sources, in concentrations that are directly indicative of diffusion through the street canyons. The findings represent a target for dispersion modeling studies that can address more than the short-term intensive data sets of the past.
ARL workers from four Divisions are now addressing the question of how best to make use of data from such sources “of opportunity.”
Contact information: Bruce B. Hicks
Phone: (301) 713-0684