September 2004

The code for computing deposition velocities for secondary organic aerosols and their precursors was generalized to facilitate additions of model species that are not part of either the gas-phase or aerosol mechanisms. All documentation relative to this and other model changes was also finalized for inclusion in the model archive and model release notes. (Gerald L. Gipson, 919 541 4181)

Improvements to the CMAQ aerosol module during FY-2004 include computational efficiency improvements in the coagulation and secondary organic aerosol routines, numerical stability improvements in the inorganic thermodynamic routine, and extensive in-line documentation enhancements throughout the aerosol code. (Prakash Bhave, 919 541 2194)

Community Multiscale Air Quality (CMAQ) Modeling System - Mercury Modeling. The first simulation of an entire annual cycle using the CMAQ mercury model was completed during September. This simulation was performed in two segments, one beginning in January 2001 and the other beginning in July 2001. A 10-day model spin-up period was used for each time segment and continuity between time segments at the June 30 - July 1 interface has been demonstrated. The simulated annual total wet deposition of mercury has been compared to observations from the Mercury Deposition Network. A Pearson correlation of 0.80 was found between the simulated and observed values of total mercury wet deposition at 52 sites across the United States and Canada. Dry deposition was also simulated by the CMAQ mercury model. It showed that in many areas of the model domain, dry deposition represents a significant fraction of the total deposition of atmospheric mercury. Analysis of these results is continuing to refine the model evaluation to a seasonal basis and to identify any relationships that might exist between model accuracy and climatic variation. (Russell Bullock, 919 541 1349)

NOAA/EPA Air Quality Forecast Model Developments. Results from three modeling streams being run this summer at the NOAA National Centers for Environmental Prediction are being assessed: ozone forecasts over the northeast United States, ozone forecasts over the eastern United States, and ozone and PM forecasts over the eastern United States have been continually analyzed on a daily basis. Guided by these analyses, diagnostic simulations to test alternate model formulations to improve the representation of the effects of clouds on photolysis attenuation have been performed. The specification of below-cloud attenuation of the photolysis rates based on radiation fields from the meteorological model was explored. In this approach, the attenuation factor was derived as the ratio of the radiation reaching the surface to the clear sky value. Simulations with this alternate formulation result in improvements in model predictions (reductions in model high bias) at the low O₃ range. Refinements to the methodology and testing over a wider range of conditions is underway. (Rohit Mathur, 919 541 1483)

Emission Inventory Assessment Readied for NARSTO Review. NARSTO’s Emission Inventory Assessment has progressed through numerous preliminary drafts and is available for review by the NARSTO community. Motivated by recommendations in NARSTO’s PM and Ozone Assessments as well as by findings from the October 2003 Emission Inventory Workshop in Austin, Texas, this Assessment’s primary goals are to set the stage for future inventory development, as well to facilitate efficient and reliable inventory application for atmospheric-process evaluation and for pollution management. Intended for a diverse audience of planners, policy makers, and scientists, the Assessment provides a staged presentation, which:

• describes a "vision," in the form of a desired future state of emission-inventory science and applications;
• provides a location and access resource for all important, currently existing North American inventories;
• analyzes deficiencies and uncertainties in current inventories;
• establishes the foundations of a rigorous approach to quantifying and reporting uncertainties in emission estimates;
• describes evolving measurement and interpretive technologies, which are potentially applicable for future emission-inventory development and/or verification; and
• outlines findings and recommendations for advancing from the present state of emission-inventory development to the visionary state described above.

This Assessment’s review schedule will be similar to those of the earlier NARSTO documents. The current draft is intended primarily for review by members of the NARSTO community; but comments are welcome from any interested individual, regardless of NARSTO affiliation. Comments, which should be sent electronically to Diane Fleshman (diane@owt.com), will be compiled and used to prepare a subsequent draft, which will be subjected to an extended review by a smaller number of selected, independent scientists. The resulting comments will be processed into a final draft, which will be published as a NARSTO document subsequent to approval by the Executive Assembly. This version contains essentially all of the technical material intended by its authors; however, it does not include an executive summary. Based on past experience with the PM and Ozone Assessments, we anticipate substantial modifications to occur as a result of the review process.

Comments for this review stage are due by October 29, 2004. The document, "Improving Emission Inventories for Effective Air-Quality Management Across North America," can be downloaded from http://www.cgenv.com/narsto/ . (J. David Mobley, 919-541-4676)

SCIENTIFIC ACCOMPLISHMENTS

Community Multiscale Air Quality (CMAQ) Modeling System - Air Toxics Modeling. On September 7, a briefing was presented to EPA/Office of Air Quality Planning and Standards (OAQPS) management and staff on applications of the Community Multiscale Air Quality (CMAQ) aerosol module for toxic air pollution modeling. The objective of the briefing was to let OAQPS know that CMAQ can be used to predict the concentrations of toxic air pollutants across the continental United States, in support of EPA’s National Air Toxics Assessment. We noted several major findings on the behavior of toxic pollutants, including the overwhelming role of atmospheric production on the concentrations of some hazardous air pollutants ( HAPs) (such as the aldehydes) as opposed to emissions, and the large variations in concentrations between seasons. (Deborah Luecken, 919 541 0244)

Work has begun on starting an annual CMAQ model simulation for specific air toxics based on the SAPRC99 mechanism for atmospheric chemistry. Results will be compared to an earlier simulation based on the CB-IV mechanism. For the SAPRC99 simulations, all emission files have been produced after correcting errors that omitted emissions from biogenic sources. Current efforts are producing the meteorological inputs by using version 2.3 of the Meteorology-Chemistry Interface Program in the CMAQ modeling system. Remaining efforts will upgrade the CMAQ chemical transport model to the version released in October 2004. Additional work was started to better interpret the SAPRC99 simulations by investigating the role of biogenic emissions in formaldehyde and acetaldehyde predictions. (William T. Hutzell, 919 541 3425)

CONFERENCES, WORKSHOPS, AND PRESENTATIONS

Air Quality Forecast Focus Group Meeting. Several ASMD personnel attended the Air Quality Forecast Focus Group Meeting held in Silver Spring, Maryland, during September 8-9, 2004. The intent of the meeting was to obtain feedback on this summer’s forecast results from state and local forecasters who comprise the Focus Group. At the meeting, Rohit Mathur gave a presentation on CMAQ enhancements and diagnostic analysis of the 2004 AQF applications, and Brian Eder gave a presentation on performance evaluation of the 2004 AQF results. Following the Focus Group meeting, a day long meeting with National Centers for Environmental Prediction involved discussions on further enhancements to the air quality forecasting system. (Rohit Mathur, 919 541 1483)

R. Mathur, J. Pleim, K. Schere, J. Young, T. Otte, G. Pouliot, B. Eder, D. Kang, S. Yu, H.-M. Lin. The Community Multiscale Air Quality (CMAQ) Model: Model configuration and enhancements for air quality forecasting. Presentation at the 2004 Air Quality Forecasting Focus Group Meeting, Silver Spring, Maryland, September 8-9, 2004

Texas Commission on Environmental Quality. On October 14 - 15, 2004, the Texas Commission on Environmental Quality is hosting a planning meeting for the Texas Air Quality Field Study called TexAQS II. Staff from EPA Region 6, EPA Office of Research and Development, and National Exposure Research Laboratory are participating. The participants at the workshop will further develop a draft field study plan for TexAQS II and the workshop will include presentations on workgroup activities that have taken place over the summer and since the February 2004 planning meeting. The study will build on the TexAQS 2000, which opened new doors to understanding air pollution and pollution controls in the Houston area during August and September 2000. The field study will be conducted from May 2005 through October 2006 and will focus on air quality topics in the eastern half of the state. The study will look at a larger area over a longer time than TexAQS 2000. A higher level of participation and contributions is also expected from researchers around the country. The TexAQS II Air Quality Field Study will include over 200 national experts from universities, state, federal and local agencies, private industry and environmental organizations to find air quality solutions for Texas. Details of the TexAQS II effort can be found at the Texas Commission on Air Quality website http://www.tceq.state.tx.us/policy/ta/am/TexAQS_II.html. (J. David Mobley, 919 541 4676)

PUBLICATIONS

Bowker, G.E., S.G. Perry, and D.K. Heist. A comparison of airflow patterns from the QUIC model and an atmospheric wind tunnel for a two-dimensional building array and a multi-city block region near the World Trade Center site. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. Joint Session J5: Fast Response Urban Dispersion Models (Joint between the Fifth Symposium on the Urban Environment and the 13th Conference on the Applications of Air Pollution Meteorology with the A&WMA). American Meteorological Society, Boston, Paper J5.4 (2004).

Burian, S.J., M.J. Brown, J.K.S. Ching, M.L. Cheuk, M. Yuan. W.S. Han, and A.T. McKinnon. Urban morphological analysis for mesoscale meteorological and dispersion modeling applicatons: current issues. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. American Meteorological Society, Boston, Paper 9.1 (2004).

Burian, S.J., S.W. Stetson, W.S. Han, J.K.S. Ching, and D.W. Byun. High-resolution dataset of urban canopy parameters for Houston, Texas. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. American Meteorological Society, Boston, Paper 9.3 (2004).

Ching, J.K.S., S. Dupont, R. Gilliam, S. Burian, and R. Tang. Neighborhood scale air quality modeling in Houston using urban canopy parameters in MM5 and CMAQ with improved characterization of mesoscale lake-land breeze circulation. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. American Meteorological Society, Boston, Paper 9.2 (2004).

Ching, J.K.S., T.E. Pierce, T. Palma, W.T. Hutzell, R. Tang, A. Cimorelli, and J. Herwehe. Linking air toxic concentrations from CMAQ to the HAPEM5 exposure model at neighborhood scales for the Philadelphia area. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. Joint Session J4: Human Biometeorology: Air Quality (Joint between the 16th Conference on Biometeorology and Aerobiology and the Fifth Symposium on the Urban Environment). American Meteorological Society, Boston, Paper J4.4 (2004).

Dupont, S., T.L. Otte, and J.K.S. Ching. Simulation of meteorological fields within and above urban and rural canopies with a mesoscale model (MM5). Boundary-Layer Meteorology 113:111-158 (2004).

Etyemezian, V., S. Ahonen, D. Nickolic, J. Gillies, H. Kuhns, D. Gillette, and J. Veranth. Deposition and removal of fugitive dust in the arid Southwest: Measurements and model results. Journal of Air & Waste Management Association 54:1099-111 (2004).

Heist, D.K. S.G. Perry, and G.E. Bowker. Evidence of enhanced vertical dispersion in the wakes of tall buildings in wind tunnel simulations of lower Manhattan. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. Joint Session 7: Special Session in Honor of Dr. E. Plate. American Meteorological Society, Boston, Paper 7.5 (2004).

Herwehe, J.A., J.K.S. Ching, and J. Swall. Quantifying subgrid pollution variability in Eulerain air quality models. 13th Conference on the Applications of Air Pollution Meteorology with the Air & Waste Management Association, Vancouver BC, Canada, August 23-26, 2004. Session 7: Variability and Uncertainty. American Meteorological Society, Boston, Paper 7.5 (2004).

Huber, A., and W. Tang, A. Flowe, B. Bell, K. Kuehlert, and W. Schwartz. Development and applications of CFD simulations in support of air quality studies involving buildings. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. Joint Session J2: Urban Scale Dispersion and Air Quality (Joint between the Fifth Symposium on the Urban Environment and the 13th Conference on the Applications of Air Pollution Meteorology with the A&WMA). American Meteorological Society, Boston, Paper J2.2 (2004).

Lee, S.-M., H.J.S. Fernando, D.W. Byun, and J.K.S. Ching. CFD modeling of fine scale flow and transport in the Houston Metropolitan Area, Texas. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. American Meteorological Society, Boston, Paper 9.12 (2004).

Okin, G.S., and D. Gillette. Modeling wind erosion and dust emission on vegetated surfaces. In Spatial Modeling of the Terrestrial Environment. Kelly, R.E., N.A. Drake, and S.L. Barr, (Eds.). John Wiley & Sons Ltd., Chichester, England, 127-156 (2004).

William, D.J., and J.K.S. Ching. A federated partnership for urban meteorological and air quality modeling. Fifth Symposium on the Urban Environment, Vancouver BC, Canada, August 23-26, 2004. American Meteorological Society, Boston, Paper 9.6 (2004).

Yu, S., R.L. Dennis, P.V. Bhave, and B.K. Eder. Primary and secondary organic aerosols over the United States: estimates on the basis of observed organic carbon (OC) and elemental carbon (EC), and air quality modeled primary OC/EC rations. Atmospheric Environment 38:5257-5268 (2004).

Prepared by:

Evelyn M. Poole-Kober, Librarian
October 19, 2004

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