Homeland Security and Defense
Both intentional and accidental releases of harmful particles or gases into the atmosphere can have devastating effects on human health and welfare through overwhelming impacts on the economy, environment, and critical infrastructure. Prevention of airborne releases is, of course, the first order of defense, but in the case of an actual release, effective preparedness and response are critical through the initial phases (days), and solid methods of characterization, restoration, and recovery are critical through the months to perhaps years of returning to usual activities.
Our primary research area for the U.S. Department of Homeland Security (DHS) is in advancing the scientific foundations and analysis tools for addressing the dispersion and fate of airborne materials in complex environments such as urban areas, coastal regions, and mountainous areas. Specific focus areas include:
- Advance our understanding of airborne dispersion through the outdoor, indoor, and underground (e.g., subway) spaces in urban areas by conducting field and modeling studies. This results in improved guidance and tools to enable planners and responders to better prepare for responding to and recovering from airborne releases.
- Advance, evaluate, and validate operational atmospheric dispersion and fate models used in planning for, responding to, characterizing, and recovering from airborne releases of harmful particulate and gaseous materials. Areas for model improvement include treating deposition to urban surfaces, resuspension of deposited material, exchanges between outdoors, indoors, and subways, and effects of urban processes on meteorology and atmospheric dispersion.
- Continue to serve as the national resource for DHS needs in evaluating, characterizing, and improving the use of national meteorological resources in effective planning for, responding to, and recovering from airborne releases. This includes developing, evaluating, and improving guidance and tools (including wind field models) for addressing atmospheric dispersion, and evaluating and improving meteorological networks for properly measuring winds, turbulence, and the structure of the atmospheric boundary layer.
- Develop, evaluate, and improve guidance and tools for placement of air samplers measuring harmful airborne materials, and the interpretation of air sampling results.
Our scientists have led and are currently leading and participating in several research projects for DHS focused on improving our understanding and modeling of meteorology and dispersion in and around urban areas and improving our preparedness for responding to threats from harmful airborne materials. We have led three major national urban tracer and meteorological studies with large multi-agency, multi-laboratory, and university teams: Urban 2000 (Salt Lake City); Urban 2003 (Oklahoma City); and Urban Dispersion 2005 (New York City). These studies gathered unique and valuable data for improving our understanding and modeling of dispersion in urban areas. The recently-conducted New York City field studies are part of the DHS Urban Dispersion Program, led by our staff, to provide improved models, an improved meteorological network, and detailed first-responder guidance for application in New York City.
In addition, our staff provide improved meteorological and dispersion formulations for the DHS Biological Warning and Incident Characterization (BWIC) system and the Rapidly Deployable Chemical Defense System (RDCDS). For both systems, the proper treatment of complex meteorological flows (e.g., land-sea breezes, mountain-valley winds) is critical for effective emergency response and post-event characterization. For RDCDS, we designed and integrated a portable meteorological network into RDCDS for the proper interpretation of positive measurements on the chemical sensors. We also provide on-site meteorological expertise during deployment of RDCDS to special national events.
A key element to improving response capabilities in the event of airborne releases of harmful materials is in improving meteorological networks and enhancing the use of existing National Weather Service products, such as information from the national network of weather radars. PNNL researchers are leading an effort for DHS to extract three-dimensional fields of horizontal wind from weather radars and to provide these wind fields to atmospheric dispersion models. These radar-derived wind fields will considerably improve the amount of wind data above the surface, thus better-defining wind-direction shears above the surface. As part of the New York City Urban Dispersion Program, our scientists are leading the improvement of a meteorological network there by installing remote wind sensing instruments to better describe the vertical variation of horizontal winds above the city. Additionally, as part of the installation of the BWIC system at cities, we are leading the identification and evaluation of existing meteorological resources in and around the cities for their reliability in properly representing wind transport of airborne materials.
