What Have Urban Experiments Taught Us About Atmospheric Flow and Transport?
This page finalized July 26, 2007
Chair’s Air Pollution Seminar
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Wednesday, August 15, 2007
1:30 p.m. - 3:30 p.m.
Sierra Hearing Room, Second Floor
1001 I Street, Sacramento
This
event is being Webcast, click here to view
Webcast viewers: Please send your
questions during broadcast to: sierrarm@calepa.ca.gov
Presentation is available at this link
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What Have Urban
Experiments Taught Us About
Atmospheric Flow and Transport?
(Urban Flow and Transport Model Development and
Evaluation with Field Experiments)
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Julie K. Lundquist, Ph.D.
National Atmospheric Release Advisory Center
Lawrence Livermore National Laboratory
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Releases of hazardous materials such as toxic industrial chemicals or chemical/biological agents, whether due to
industrial accidents or terrorist releases, pose significant risks to civilian populations. Urban areas are the
most consequential locations for such releases due to large populations and difficult evacuation logistics; however,
urban areas often experience complex non-uniform winds which cannot be easily predicted by conventional transport
and dispersion models. For advance planning, for emergency response, and for determining community exposure, observational
and modeling tools designed specifically for urban areas can be used to predict and track the transport and dispersion
of these hazardous materials.
Verification and validation of these tools is possible using data from field experiments. We discuss insights gleaned
from the Joint URBAN 2003 (JU2003) urban dispersion experiment (Oklahoma City, July 2003), the largest urban dispersion
experiment to date. We compare observed dispersion patterns with those predicted with several of the urban modeling
tools utilized by Lawrence Livermore National Laboratory's (LLNL's) National Atmospheric Release Advisory Center
(NARAC). In densely built-up areas, like an urban core, the mechanical production of turbulence, which can be simulated
with a computational fluid dynamics model like NARAC's FEM3MP, dominates the flow and dispersion. FEM3MP simulations
agree quite well with observations in Oklahoma City's urban core, even when using a mixed virtual-explicit building
simulation approach to increase computational efficiency.
Because the source of a release is often unknown during the critical emergency response phase, LLNL has also developed
a methodology for discerning the strength and location of an accidental release from sparse observations. Examples
of this "event reconstruction" based on the JU2003 releases show that our approach can successfully identify
sources of these releases. Both conventional forward simulation tools and this backward event reconstruction methodology
are important components of response to releases of hazardous materials. |
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Julie K. Lundquist, Ph.D., is a staff scientist in the Energy and Environment Directorate
at Lawrence Livermore National Laboratory, where she has been employed since 2002. Dr. Lundquist's research synthesizes
observations of the atmospheric boundary layer with innovative data analysis methods and numerical simulations
in order to improve our understanding and prediction of transport and diffusion in the atmosphere. Her work directly
supports the National Atmospheric Release Advisory Center (NARAC). Dr. Lundquist is particularly interested in
the intermittent and inhomogeneous turbulence observed in urban and stable boundary layers and methods for parameterizing
turbulence in numerical weather prediction models.
Dr. Lundquist obtained her Ph.D. in Astrophysical, Planetary, and Atmospheric Science from the University of Colorado
at Boulder in 2001, following a Bachelors degree in English and Physics at Trinity University and a M.S. degree
from the University of Colorado at Boulder. |
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For more information on this
Seminar please contact:
Eileen McCauley at (916) 323-1534 or send email to: emccaule@arb.ca.gov
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the ARB Chairman's Series and the related documentation for each one of the series please check this page
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