Grantee Research Project Results
1999 Progress Report: Development and Evaluation of Modeling Techniques for the Study of Interactions between Urban and Point Source Plumes and Regional Atmospheres in the Formation of Secondary Pollutants
EPA Grant Number: R827028Title: Development and Evaluation of Modeling Techniques for the Study of Interactions between Urban and Point Source Plumes and Regional Atmospheres in the Formation of Secondary Pollutants
Investigators: Odman, Mehmet Talat , McRae, D. Scott
Institution: Georgia Institute of Technology , North Carolina State University
Current Institution: Georgia Institute of Technology
EPA Project Officer: Hahn, Intaek
Project Period: January 15, 1999 through January 14, 2002 (Extended to March 31, 2002)
Project Period Covered by this Report: January 15, 1999 through January 14, 2000
Project Amount: $468,324
RFA: Air Pollution Chemistry and Physics (1998) RFA Text | Recipients Lists
Research Category: Air , Air Quality and Air Toxics , Safer Chemicals
Objective:
The purpose of the study is to develop new modeling techniques and build on existing ones to improve the representation of emission sources in air quality models (AQMs). The interaction of point and urban source plumes with the surrounding atmosphere involves processes of critical importance to the formation, long-range transport and fate of secondary pollutants such as ozone. Various reactive plume models were imbedded in AQMs to better resolve point source plumes, but no real benefits were reported other than those in the immediate vicinity of the sources. It is suspected that this is due to underestimating the magnitude of numerical diffusion at grid scales where information is typically transferred from the subgrid scale plume model to the grid model. Hand-over criteria will be designed considering chemical state as well as the potential numerical diffusion of the plume. Modeling techniques will be developed that can better resolve urban plumes and provide local grid refinements for a better interface with subgrid scale models.Progress Summary:
In the first year, research focused on the development of mass conservative techniques for coupling AQMs with meteorological models (MMs), design of hand-over criteria for subgrid scale reactive plume models, and the development of an adaptive grid AQM. Three methods for making the meteorological fields consistent were implemented and incorporated into an AQM. Comparisons showed that the wind fields produced by the three methods were very similar to each other but they differed from those supplied by the MM. The differences were not large enough to significantly affect any transport trajectories though, just sufficient to assure conservation of mass. A formal analysis of numerical diffusion introduced during the hand-over of the plume from the subgrid scales of the reactive plume model to the grid scales of AQM has been started. The frequencies present in the plume at each scale are being analyzed in order to formalize criteria for accurate hand-over of the plume. The development of adaptive grid AQM also has started. First, the adaptor was tested using complex terrain elevation fields, which, in terms of variability, are similar to secondary air pollutant fields. Starting with a uniform grid with four times less resolution than the original data, the grid was adapted with the objective of recovering the resolution of the original data as much as possible. The adaptor displayed very slow convergence in an application to the terrain of the United States-Mexico border. Investigations showed that this was due to significant terrain features near the boundary of the domain. The adaptor requires that the domain boundaries be placed far away from important features in the fields. A second application used elevation data for a domain with the boundaries over the ocean and the island of Hawaii in the center. This time, the adaptor performed well but required several modifications to improve its convergence characteristics. Among the most important components of the adaptive grid AQM are the processors for emissions and meteorological inputs. Since the processing must be performed after each grid adaption during the simulation, it is critical to design efficient processors that consume very little computational time. We have started to develop efficient intersection and search algorithms for input data processing. These algorithms take advantage of the fact that the topology of the grid is maintained during adaption, although the location and shape of the grid cells change. Finally, we acquired very high-resolution (4 x 4 km) meteorological data for a region that covers Northern Alabama and Southern Tennessee. The presence of large power plant plumes makes this region ideal for evaluating the performance of the adaptive grid AQM. We also have started gathering the emissions data for this domain.Future Activities:
During the next year, we expect to: (1) continue the development of adaptive grid AQM and its emissions and meteorological data processing components; (2) continue the design of criteria for adaption; (3) finish data preparation for simulations with AQM; (4) perform preliminary simulation of an ozone episode with AQM; and (5) verify the adaptive grid AQM results.Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 14 publications | 7 publications in selected types | All 4 journal articles |
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Type | Citation | ||
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Srivastava RK, McRae DS, Odman MT. An adaptive grid algorithm for air-quality modeling. Journal of Computational Physics 2000;165(2):437-472. |
R827028 (1999) R827028 (2001) |
Exit Exit |
Supplemental Keywords:
tropospheric, oxidants, nitrogen oxides, mathematics, analytical, Northeast., RFA, Scientific Discipline, Air, Geographic Area, Environmental Chemistry, Physics, Chemistry, mobile sources, tropospheric ozone, Engineering, Chemistry, & Physics, East Coast, air quality standards, fate and transport, Fourier Transform Infrared measurement, urban air, subgrid scale models, air quality models, air modeling, air pollution models, point source effluents, regional atmospheres, troposphere, mathematical formulations, nitrogen removal, urban air , measurement methods , plume dispersion modelsRelevant Websites:
http://environmental.gatech.edu/~odman/Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.