A Comparison Study in Response to the Proposed Replacement of CALINE3 with AERMOD in Appendix W
1 like1,111 views
This document presents a comparative study evaluating the performance of air dispersion models, specifically aermod and caline3, in response to the U.S. EPA's proposed replacement of caline3 with aermod for mobile source applications. Utilizing a field study conducted in downtown Los Angeles, the evaluation indicates that aermod performs better than caline3 when meteorological data from the study site is used. The findings support the proposed replacement as aermod accounts for air dispersion based on modern turbulence structures and terrain complexities.
A Comparison Study in Response to the Proposed Replacement of CALINE3 with AERMOD in Appendix W
- 1. 1 A Comparison Study in Response to the Proposed Replacement of CALINE3 with AERMOD in Appendix W Extended Abstract # 37 Presented at the conference: Guideline on Air Quality Models: The New Path April 12-14, 2016 Chapel Hill, NC Weiping Dai,1 Qiguo Jing,1 Tiffany Gardner,2 Brian Holland1; 1Trinity Consultants Inc., Dallas, TX, 2Trinity Consultants Inc., Charlotte, NC INTRODUCTION The current version of U. S. EPA’s Guideline on Air Quality Models, published as Appendix W to 40 CFR Part 51 (Appendix W) in 2005, addresses modeling mobile sources using CALINE3- based models (CALINE4 1 , CAL3QHC 2 , and CAL3QHCR 3 ), with specific recommendations for each criteria pollutant, such as CO, Pb, NO2, PM, and SO2. CALINE3 was developed in the late 1970’s using P-G stability classes as the basis for the dispersion algorithms. CALINE3- based models used in quantitative hot-spot analyses have not undergone major updates since 1995 and have limitations in simulating air quality impacts of complex urban roadway networks. Zhang and Gao shows the increased turbulence due to vehicles and roads 4 ; Schulte and Venkatram shows that infinitely long roadside sound barriers increase vertical dispersion, induce vertical mixing and loft the emissions above the barrier 5 , and Schulte et al. indicates the rapid vertical dispersion due to the presence of roadside buildings 6 . The recent proposed revisions to Appendix W include the proposal to remove CALINE3 for mobile source applications and replace it with AERMOD 7 , which incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concepts, and includes treatment of both surface and elevated sources, and both simple and complex terrain. In addition, the LINE and AREA source options in AERMOD implement a full numerical integration of emissions across the LINE and AREA sources. This proposed replacement is supported by two model performance comparison studies conducted by U. S. EPA 8 . One evaluates the CALTRANS 99 field study conducted along Highway 99 outside Sacramento, CA; the other evaluates the Idaho Falls, ID, field study conducted in an open field with a barrier between the line source and receptors. Both evaluations indicate that AERMOD performs better than CALINE4. However, both field studies do not represent either a suburban area with low building density or deep urban canyons with dense urban environments. This paper compares AERMOD with CALINE3-based models and RLINE (a research model specifically for roadway sources developed by U. S. EPA's Office of Research and Development) 9 using a field study conducted in downtown Los Angeles in 2008. The evaluation supports the proposed replacement when AERMOD is executed with onsite meteorological data.
- 2. 2 MODEL EVALUATION Description of Field Study Figure 1 refers to a 400 m × 350 m area in downtown Los Angeles (LA) covering high-rise buildings and skyscrapers. The heights of the buildings vary from 5 to 187 m. The streets are three-lane one-way roadways. There are two street parking lanes on both sides. The street width is about 13 m. The field measurements were conducted during the weekdays from June 19, 2008 to August 1, 2008. Experiments were conducted for three days. Meteorological measurements lasted 12 hours for each day from morning (about 7:00 a.m.) to late afternoon (about 7:00 p.m.). DustTraks covered the morning (7:00 a.m. to ~ 9:00 a.m. local time), evening (5:00 p.m. to ~ 7:00 p.m. local time) commute and lighter mid-day (11:00 a.m. to ~ 1:00 p.m. local time) traffic. DustTraks collected 1 Hz PM2.5 for 6 hours. Traffic flows were recorded using digital cameras and manually counted afterwards.10 The averaged vehicle PM2.5 emission rate among different fleet mixes was calculated based on EMFAC 2014.11 The fugitive PM2.5 emission rate from paved roads was calculated based on CARB’s miscellaneous process methodology 7.9.12 The resulting PM2.5 emission rate is 0.16 g/km. Figure 1. Site Distribution in High-rise Settlement-Los Angeles. The Numbers Marked on Buildings Show Height in Meters. 10 LA6 LA2 LA3 LA4 LA1 LA5 104 44 14 15 53 46 951 48 72 97 13 5052 52 50 1916 25 5 5 20 28 11 45 47 12 50 48 46 58 48 52 11 44 14 43 39 10 125 1219 11 1015 36 106 101 46 52 35 33 7 422015 4651 52 29 7077 50 7 9 14 38 41 60 43 30 22 28 18 17 54 4648 10 14 187 124 119 104 24 21 112 51 43 2421 26 155 7 21 DustTrak Sonic Anemometer Camera
- 3. 3 Model Performance Figure 2 shows the Quantile-Quantile (Q-Q) plot for the downtown LA field study. Q-Q plots are typically used to show model performance for ranked concentrations, which do not pair in time and location. It can be seen from Figure 2 that CALINE4 with onsite meteorological data generally overestimates the PM2.5 concentrations for all concentrations ranges. This could be an indication that CALINE4 does not provide enough vertical mixing since CALINE4 does not require an input for standard deviation of vertical wind speed (σw). AERMOD with onsite meteorological data, especially the measured σw, appears to perform the best of all the dispersion models, being closest to the 1:1 line. AERMOD with nearby airport (LAX) meteorological data, however, has the worst performance over all concentration ranges. RLINE with onsite meteorological data has similar performance to AERMOD with onsite data, but it overestimates the highest concentration substantially. All dispersion models with onsite data tend to overestimate the high-end concentrations. Figure 2. Q-Q Plot for Downtown LA Field Study SUMMARY In response to the proposed replacement of CALINE3 with AERMOD in Appendix W, this paper compares air dispersion models’ performance using a field study conducted in downtown
- 4. 4 LA, a typical high-rise unban environment. The results support the proposed replacement when onsite meteorological data is used as inputs to AERMOD. ACKNOWLEDGEMENTS We thank Professor Marko Princevac and his research team for providing us with the data collected in downtown LA. REFERENCES 1. Benson, P. CALINE4--a dispersion model for predicting air pollutant concentrations near roadways; California Department of Transportation, Sacramento, CA, 1984: FHWA-CA-TL- 84-15. 2. U. S. EPA. User's guide to CAL3QHC version 2.0: A modeling methodology for predicting pollutant concentrations near roadway intersections (revised); OAQPS, RTP, NC, 1995: EPA-454/R-92-006R. 3. Eckhoff, P.; Braverman, T. Addendum to the User's Guide to CAL3QHC Version 2.0 (CAL3QHCR User's Guide); OAQPS, RTP, NC, 1995. 4. Zhang, K. M.; Gao, H. O. Development of Advanced Modeling Tools for Hotspot Analysis of Transportation Emissions; Report No. 49777-22-19. University Transportation Research Center, Region 2, 2009. 5. Schulte, N.; Venkatram, A. Effects of Sound Barriers on Dispersion from Roadways; South Coast Air Quality Management District, 2013 6. Schulte, N.; Tan, S.; Venkatram A. The ratio of effective building height to street width governs dispersion of local vehicle emissions; Atmospheric Environment: 2015, 112, 54-63. 7. Cimorelli, A. J.; Perry, S. G.; Venkatram, A.; Weil, J. C.; Paine, R.; Wilson, R. B.; Lee, R. F.; Peters, W. D.; Brode, R. W. AERMOD: A Dispersion Model for Industrial Source Applications. Part I: General Model Formulation and Boundary Layer Characterization; Journal of Applied Meteorology: 2005, 44, 5:682-693. 8. U. S. EPA. Technical Support Document (TSD) for Replacement of CALINE3 with AERMOD for Transportation Related Air Quality Analyses; OAQPS, RTP, NC, 2015: EPA- 454/B-15- 002. 9. Snyder, M. G.; Heist D. K. User’s Guide for R-Line Model Version 1.2: A Research Line Source Model for Near-Surface Releases; U. S. EPA/ORD/NERL, RTP, NC, 2013: MD-81. 10. Pan, H.; Bartolome, C.; Gutierrez, E.; Princevac, M.; Edwards, R.; Boarnet, M. G.; Houston, D. Investigation of roadside fine particulate matter concentration surrounding major
- 5. 5 arterials in five Southern Californian cities; Journal of the Air & Waste Management Association, 2013, 63, 4: 482-498. 11. CARB. EMFAC 2014 User Guide; Mobile Source Analysis Branch, Air Quality Planning & Science Division, 2014. 12. CARB. Miscellaneous Process Methodology 7.9 – Entrained Road Travel, Paved Road Dust; 2014.