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Title: A case study of the Weather Research and Forecasting model applied to the Joint Urban 2003 tracer field experiment. Part 2: Gas tracer dispersion

Abstract

Here, the Quick Urban & Industrial Complex (QUIC) atmospheric transport, and dispersion modelling, system was evaluated against the Joint Urban 2003 tracer-gas measurements. This was done using the wind and turbulence fields computed by the Weather Research and Forecasting (WRF) model. We compare the simulated and observed plume transport when using WRF-model-simulated wind fields, and local on-site wind measurements. Degradation of the WRF-model-based plume simulations was cased by errors in the simulated wind direction, and limitations in reproducing the small-scale wind-field variability. We explore two methods for importing turbulence from the WRF model simulations into the QUIC system. The first method uses parametrized turbulence profiles computed from WRF-model-computed boundary-layer similarity parameters; and the second method directly imports turbulent kinetic energy from the WRF model. Using the WRF model’s Mellor-Yamada-Janjic boundary-layer scheme, the parametrized turbulence profiles and the direct import of turbulent kinetic energy were found to overpredict and underpredict the observed turbulence quantities, respectively. Near-source building effects were found to propagate several km downwind. These building effects and the temporal/spatial variations in the observed wind field were often found to have a stronger influence over the lateral and vertical plume spread than the intensity of turbulence. Correcting the WRF modelmore » wind directions using a single observational location improved the performance of the WRF-model-based simulations, but using the spatially-varying flow fields generated from multiple observation profiles generally provided the best performance.« less

Authors:
 [1];  [1];  [1];  [2];  [3];  [2];  [4]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Aeris, Louisville, CO (United States)
  3. Citadel, Chicago, IL (United States)
  4. Science and Technology in Atmospheric Research (STAR) LLC, Boulder, CO (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1331258
Report Number(s):
LA-UR-14-29367; LA-UR-17-27317
Journal ID: ISSN 0006-8314
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Boundary-Layer Meteorology
Additional Journal Information:
Journal Name: Boundary-Layer Meteorology; Journal ID: ISSN 0006-8314
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Quick Urban and Industrial Complex modelling system; Transport and dispersion; Weather Research and Forecasting model

Citation Formats

Nelson, Matthew A., Brown, Michael J., Halverson, Scot A., Bieringer, Paul E., Annunzio, Andrew, Bieberbach, George, and Meech, Scott. A case study of the Weather Research and Forecasting model applied to the Joint Urban 2003 tracer field experiment. Part 2: Gas tracer dispersion. United States: N. p., 2016. Web. doi:10.1007/s10546-016-0188-z.
Nelson, Matthew A., Brown, Michael J., Halverson, Scot A., Bieringer, Paul E., Annunzio, Andrew, Bieberbach, George, & Meech, Scott. A case study of the Weather Research and Forecasting model applied to the Joint Urban 2003 tracer field experiment. Part 2: Gas tracer dispersion. United States. doi:10.1007/s10546-016-0188-z.
Nelson, Matthew A., Brown, Michael J., Halverson, Scot A., Bieringer, Paul E., Annunzio, Andrew, Bieberbach, George, and Meech, Scott. 2016. "A case study of the Weather Research and Forecasting model applied to the Joint Urban 2003 tracer field experiment. Part 2: Gas tracer dispersion". United States. doi:10.1007/s10546-016-0188-z. https://www.osti.gov/servlets/purl/1331258.
@article{osti_1331258,
title = {A case study of the Weather Research and Forecasting model applied to the Joint Urban 2003 tracer field experiment. Part 2: Gas tracer dispersion},
author = {Nelson, Matthew A. and Brown, Michael J. and Halverson, Scot A. and Bieringer, Paul E. and Annunzio, Andrew and Bieberbach, George and Meech, Scott},
abstractNote = {Here, the Quick Urban & Industrial Complex (QUIC) atmospheric transport, and dispersion modelling, system was evaluated against the Joint Urban 2003 tracer-gas measurements. This was done using the wind and turbulence fields computed by the Weather Research and Forecasting (WRF) model. We compare the simulated and observed plume transport when using WRF-model-simulated wind fields, and local on-site wind measurements. Degradation of the WRF-model-based plume simulations was cased by errors in the simulated wind direction, and limitations in reproducing the small-scale wind-field variability. We explore two methods for importing turbulence from the WRF model simulations into the QUIC system. The first method uses parametrized turbulence profiles computed from WRF-model-computed boundary-layer similarity parameters; and the second method directly imports turbulent kinetic energy from the WRF model. Using the WRF model’s Mellor-Yamada-Janjic boundary-layer scheme, the parametrized turbulence profiles and the direct import of turbulent kinetic energy were found to overpredict and underpredict the observed turbulence quantities, respectively. Near-source building effects were found to propagate several km downwind. These building effects and the temporal/spatial variations in the observed wind field were often found to have a stronger influence over the lateral and vertical plume spread than the intensity of turbulence. Correcting the WRF model wind directions using a single observational location improved the performance of the WRF-model-based simulations, but using the spatially-varying flow fields generated from multiple observation profiles generally provided the best performance.},
doi = {10.1007/s10546-016-0188-z},
journal = {Boundary-Layer Meteorology},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 7
}

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  • We found that numerical-weather-prediction models are often used to supply the mean wind and turbulence fields for atmospheric transport and dispersion plume models as they provide dense horizontally- and vertically-resolved geographic coverage in comparison to typically sparse monitoring networks. Here, the Weather Research and Forecasting (WRF) model was run over the month-long period of the Joint Urban 2003 field campaign conducted in Oklahoma City and the simulated fields important to transport and dispersion models were compared to measurements from a number of sodars, tower-based sonic anemometers, and balloon soundings located in the greater metropolitan area. Time histories of computed windmore » speed, wind direction, turbulent kinetic energy (e), friction velocity (u* ), and reciprocal Obukhov length (1 / L) were compared to measurements over the 1-month field campaign. Vertical profiles of wind speed, potential temperature (θ ), and e were compared during short intensive operating periods. The WRF model was typically able to replicate the measured diurnal variation of the wind fields, but with an average absolute wind direction and speed difference of 35° and 1.9 m s -1 , respectively. Then, using the Mellor-Yamada-Janjic (MYJ) surface-layer scheme, the WRF model was found to generally underpredict surface-layer TKE but overpredict u* that was observed above a suburban region of Oklahoma City. The TKE-threshold method used by the WRF model’s MYJ surface-layer scheme to compute the boundary-layer height (h) consistently overestimated h derived from a θ gradient method whether using observed or modelled θ profiles.« less
  • An atmospheric tracer dispersion study known as Joint Urban 2003 was conducted in Oklahoma City, Oklahoma during the summer of 2003. As part of this field program, vertical concentration profiles were measured at approximately 1 km from downtown tracer gas release locations. These profiles indicated that the urban landscape was very effective in mixing the plume vertically. The height of the plume centerline (as determined by the maximum concentration over the depth of the measurements) for any specific 30 min period varied over the 65 m measurement range. Most of the variations in tracer concentration observed in the profile timemore » series were related to changes in wind direction as opposed to changes in turbulence. As a simple analysis tool for emergency response, maximum normalized concentration curves were developed with 5-minute averaged measurements. These curves give the maximum concentration (normalized by the release rate) that would be observed as a function of downwind distance in an urban area. The 5-min data resulted in greater concentrations than predicted with a simple Gaussian plume model. However, the curve compared well with results from a computational fluid dynamics simulation. This dispersion dataset is a valuable asset not only for refining air quality models, but also for developing new tools for emergency response personnel in the event of a toxic release.« less
  • In the Spring of 2003, a series of dispersion field experiments (Joint Urban 2003) were conducted at Oklahoma City. These experiments were complimentary to the URBAN 2000 field studies at Salt Lake City (Allwine, et. al, 2002) in that they will provide a second set of comprehensive field data for evaluation of CFD as well as for other dispersion models. In contrast to the URBAN 2000 experiments that were conducted entirely at night, these new field studies took place during both daytime and nighttime thus including the possibility of convective as well as stable atmospheric conditions. Initially several CFD modelingmore » studies were performed to provide guidance for the experimental team in the selection of release sites and in the deployment of wind and concentration sensors. Also, while meteorological and concentration measurements were taken over the greater Oklahoma City urban area, our CFD calculations were focused on the near field of the release point. The proximity of the source to a large commercial building and to the neighboring buildings several of which have multi-stories, present a significant challenge even for CFD calculations involving grid resolutions as fine as 1 meter. A total of 10 Intensive Observations Periods (IOP's) were conducted within the 2003 field experiments. SF{sub 6} releases in the form of puffs or continuous sources were disseminated over 6 daytime and 4 nighttime episodes. Many wind and concentration sensors were used to provide wind and SF{sub 6} data over both long and short time-averaging periods. In addition to the usual near surface measurements, data depicting vertical profiles of wind and concentrations adjacent to the outside walls several building were also taken. Also of interest were observations of the trajectory of balloons that were released closed to the tracer release area. Many of the balloons released exhibit extremely quick ascents up from ground level to the top of buildings, thus implying highly convective conditions. In this paper we will present some simulations that were performed during the planning of the field experiments. The calculations were based on two possible release sites at the intersections of Sheridan and Robinson, and Broadway and Sheridan. These results provided initial information on flow and dispersion patterns, which were used to guide optimal placement of sensor at appropriate locations. We will also discuss results of more recent simulations for several releases in which reliable data is available. These simulations will be compared with the near field data taken from the wind sensors as well as the time-averaged data from the concentration sensors. Among the other topics discussed are initial and boundary conditions used in the simulations, adaptation of building GIS data for CFD modeling and analysis of field data.« less