Airborne Toxic Release/Emergency Response Sub-component.

Plume dispersion over N. Dallas simulated using the HOTMAC - RAPTAD - GASFLOW modeling system.

As part of the first-year pilot project, the dispersion of a toxic vapor spill was simulated in north Dallas. The simulation involved modeling flow and plume dispersion around two buildings and then tracking the plume over several kilometers. The microscale modeling was performed using a computational fluid dynamics model called GASFLOW and the mesoscale modeling was done with the HOTMAC-RAPTAD system. The toxic plume concentration fields were then used along with transportation simulations performed by the TRANSIMS team to compute exposures to the cars traveling through the plume.

Reports & Talks:

Summary of the Airborne Toxic Release/Emergency Response Sub-component, Brown, LA-UR-97-3931 (1997).
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The effect of microscale urban canyon flow on mesoscale puff dispersion, Brown and Muller, LA-UR-97-1143 (1997) - presented at the 12th AMS Symposium on Bound. Layers and Turb., Vancouver.
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See the Toxic Plume demo (sorry, no sound yet)

Urban Air-Water Pathways Sub-component.

Nitrogen dioxide deposition simulated over the Santa Monica Bay Watershed using the CIT air chemistry code.

We are attempting to simulate the transport of pollutants from their source through air and water pathways in an urban environment by linking cross-disciplinary subsystem models, tailoring them for urban applications, and writing interface physics modules. We are focusing on the transport and fate of nitrates because 1) they track through both the air and water pathways, 2) the physics, chemistry, and biology of the complete cycle is not well understood, 3) nitrates have important health, local ecosystem, and global climate implications, and 4) the problem requires us to stretch our capabilities in non-traditional areas, including several relating to urban infrastructure and security. Currently, we are simulating the fate of nitrates in the Los Angeles basin from their beginning as nitrate-precursors produced by auto emissions and industrial processes, tracking their dispersion and chemistry as they are transported by regional winds and eventually wet or dry deposit on the ground, tracing their path as they are entrained into surface water runoff and the stormwater system during rain events and then carried into a receiving water body where dispersion and biologically-mediated chemical reactions take place.

We have developed collaborations with leaders in different fields to complement our research efforts, including Carnegie-Mellon and Georgia Tech Universities (size-resolved particulate chemistry modeling), the UCLA Dept. of Civil Engineering (urban runoff modeling and water quality datasets), the LA Stormwater Bureau and LA Public Works Dept. (stormwater datasets and end-user expertise), the Univ. of Alabama Dept. of Civil Engineering (stormwater modeling), and the UCLA School of Public Health (biologically-mediated chemistry). Currently we are supporting five graduate students, two of whom are working at LANL on their Ph.D. dissertations. The team includes members from the EES, D, and CST divisions.

Reports & Talks:

Slides containing an overview of the Urban Air-Water Pathways research task.
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Modeling the atmospheric deposition and stormwater washoff of nitrogen compounds, Burian, Streit, McPherson, Brown, and Turin, Env. Mod. & Soft., v 16, pp 467-479, LA-UR-99-6256 (2001).
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Evaluation of land use/land cover data sets for urban watershed modeling, Burian, Brown, and McPherson, IWA 5th Int. Conf. Diffuse/Nonpoint Poll. & Watershed Management, Milwaukee, WI, LA-UR-01-4549 (2001).
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View the presentation on Evaluation of land use/land cover data sets for urban watershed modeling.
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Pollutant transfer through air and water pathways in an urban environment, Brown, Burian, McPherson, Streit, Costigan and Greene, 2nd AMS Urban Env. Conf., Albuquerque, NM, LA-UR-98-3527 (1998).
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View quicktime movies of storm water flow (0.8 Mb) and storm water quality (0.7 Mb) in one of the Santa Monica Bay sub-watersheds.

Environmental modeling and assessment using detailed urban databases, Burian, S., T. McPherson, M. Brown, G. Streit, and H.J. Turin, Earth Sciences in the Cities, AGU Monograph, eds. Heiken, Fakundiny, and Sutter, LA-UR-01-2393 (2001).

Integrated Environmental Modeling of the Urban Ecosystem, T. McPherson, S. Burian, M. Brown, G. Streit, and H. Turin, Earth Sciences in the Cities, AGU Monograph, eds. Heiken, Fakundiny, and Sutter, LA-UR-01-2348 (2001).

Development of a stormwater model for the Ballona Creek Watershed, Burian, McPherson, Brown, and Turin, LA-UR-00-1849 (2000).
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Air and water quality modeling system: application to the Los Angeles metropolitan area, Brown, Burian, McPherson, Streit, Costigan, and Turin, 2nd AMS Conf. on Env. Appl., Long Beach, CA, Jan 2000, LA-UR-99-5468 (1999).
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Modeling the Atmospheric Contribution of Nitrogen Compounds in Stormwater Runoff, Burian, Streit, McPherson, Brown, and Turin, 11th AMS Appl. Air Poll. Meteor. Conf., Long Beach, CA, Jan 2000, LA-UR-99-5218 (1999).
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