Air quality models are increasingly used to develop estimates of dry and wet deposition of sulfate and nitrate in watersheds (because of lack of measurements) in an effort to determine the acidifying deposition load into the aquatic systems. These models need to be rigorously evaluated to ensure that one can rely on the modeled quantities instead of the measured quantities. In the United State (U.S.), these models have been proposed for use in establishing national standards based on modeled quantities. The U.S. Environmental Protection Agency (EPA) is considering aquatic acidification as the main ecological endpoint of concern in determining the secondary national ambient air quality standards for nitrogen oxides and sulfur oxides. Acidification is tied to depositions of sulfur and nitrogen, which are linked to ambient concentrations of the elements. As EPA proposes to use a chemical transport model in linking deposition to ambient concentration, it is important to investigate how the currently used chemical transport models perform in predicting depositions and ambient concentrations of relevant chemical species and quantify the variability in their estimates. In this study, several annual simulations by multiple chemical transport models for the entire continental U.S. domain are evaluated against available measurement data for depositions and ambient concentrations of sulfur oxides and reactive nitrogen species. The model performance results vary by evaluation time-scale and geographical region. Evaluation of annualized quantities (annual average ambient concentrations and annual total depositions) suppresses the large variances shown in the evaluation using the observation’s native shorter-term time-scales (e.g., weekly). In addition, there is a large degree of bias and error (especially for deposition fluxes) in the modeling results that brings to question the suitability of using air quality models to provide estimates of deposition loads. Variability in the ratio of deposition to ambient concentration, so-called the Transference Ratio that EPA has proposed to use in linking deposition to ambient concentration, is also examined. Our study shows that the Transference Ratios as well as total reduced nitrogen deposition, another modeled parameter EPA proposed to use in the process of determining the new secondary standard, vary considerably by geographical region and by model simulation.
References
[1]
Environmental Protection Agency (EPA). Integrated Review Plan for the Secondary National Ambient Air Quality Standards for Nitrogen Dioxide and Sulfur Dioxide; EPA-452/R-08-006, December 2007. Available online: http://www.epa.gov/ttnnaaqs/standards/no2so2sec/cr_pd.html (accessed on 29 December 2011).
[2]
Environmental Protection Agency (EPA). Integrated Science Assessment for Oxides of Nitrogen and Sulfur Ecological Criteria (Final Report); EPA/600/R-08/082F, December 2008. Available online: http://www.epa.gov/ttnnaaqs/standards/no2so2sec/cr_isi.html (accessed on 29 December 2011).
[3]
Environmental Protection Agency (EPA). Risk and Exposure Assessment for Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur-Main Content—Final Report; EPA-452/R-09-008a, September 2009. Available online: http://www.epa.gov/ttnnaaqs/standards/no2so2sec/cr_rea.html (accessed on 29 December 2011).
[4]
Environmental Protection Agency (EPA). Policy Assessment for the Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur; EPA-452/R-11-005a, February 2011. Available online: http://www.epa.gov/ttnnaaqs/standards/no2so2sec/cr_pa.html (accessed on 29 December 2011).
[5]
Russell, A.; Samet, J.M. March 2010. Available online: http://yosemite.epa.gov/sab/sabproduct.nsf/264cb1227d55e02c85257402007446a4/0fc13c821ee6181a85257473005ae1ec!OpenDocument&TableRow=2.3#2 (accessed on 29 December 2011).
[6]
Russell, A.; Samet, J.M. December 2010. Available online: http://yosemite.epa.gov/sab/sabproduct.nsf/264cb1227d55e02c85257402007446a4/0fc13c821ee6181a85257473005ae1ec!OpenDocument&TableRow=2.3#2 (accessed on 29 December 2011).
[7]
Byun, D.W.; Ching, J.K.S. Science Algorithms of the EPA Models-3 Community Multiscale Air Quality (CMAQ) Modeling System; EPA-600/R-99-030, March 1999. Available online: http://www.epa.gov/asmdnerl/CMAQ/CMAQscienceDoc.html (accessed on 29 December 2011).
[8]
CAMx. User’s Guide—Comprehensive Air-Quality Model with Extensions, Version 5.40; ENVIRON International Corporation: Novato, CA, USA, 2011. Available online: http://www.camx.com (accessed on 29 December 2011).
[9]
Appel, K.W.; Gilliland, A.B.; Sarwar, G.; Gilliam, R.C. Evaluation of the Community Multiscale Air Quality (CMAQ) model version 4.5: Sensitivities impacting model performance Part I—Ozone. Atmos. Environ. 2007, 41, 9603–9615, doi:10.1016/j.atmosenv.2007.08.044.
[10]
Appel, K.W.; Bhave, P.V.; Gilliland, A.B.; Sarwar, G.; Roselle, S.J. Evaluation of the Community Multiscale Air Quality (CMAQ) model version 4.5: Sensitivities impacting model performance; Part II—Particulate matter. Atmos. Environ. 2008, 42, 6057–6066, doi:10.1016/j.atmosenv.2008.03.036.
[11]
Appel, K.W.; Roselle, S.J.; Gilliam, R.C.; Pleim, J.E. Sensitivity of the community multiscale air quality (CMAQ) model v4.7 results for the eastern United States to MM5 and WRF meteorological drivers. Geosci. Model Dev. 2010, 3, 169–188, doi:10.5194/gmd-3-169-2010.
[12]
Appel, K.W.; Foley, K.M.; Bash, J.O.; Pinder, R.W.; Dennis, R.L.; Allen, D.J.; Pickering, K. A multi-resolution assessment of the Community Multiscale Air Quality (CMAQ) model v4.7 wet deposition estimates for 2002-2006. Geosci. Model Dev. 2011, 4, 357–371, doi:10.5194/gmd-4-357-2011.
[13]
Foley, K.M.; Roselle, S.J.; Appel, K.W.; Bhave, P.V.; Pleim, J.E.; Otte, T.L.; Mathur, R.; Sarwar, G.; Young, J.O.; Gilliam, R.C.; et al. Incremental testing of the Community Multiscale Air Quality (CMAQ) modeling system version 4.7. Geosci. Model Dev. 2010, 3, 205–226, doi:10.5194/gmd-3-205-2010.
[14]
Baker, K.; Scheff, P. Photochemical model performance for PM2.5 sulfate, nitrate, ammonium, and precursor species SO2, HNO3, and NH3 at background monitor locations in the central and eastern United States. Atmos. Environ. 2007, 41, 6185–6195, doi:10.1016/j.atmosenv.2007.04.006.
[15]
Baker, K.; Scheff, P. Assessing meteorological variable and process relationships to modeled PM2.5 ammonium nitrate and ammonium sulfate in the central United States. J. Appl. Meteorol. Climatol. 2008, 47, 2395–2404, doi:10.1175/2007JAMC1648.1.
[16]
Rodriguez, M.A.; Barna, M.G.; Moore, T. Regional impacts of oil and gas development on ozone formation in the western United States. J. Air Waste Manag. Assoc. 2009, 59, 1111–1118, doi:10.3155/1047-3289.59.9.1111.
[17]
Rodriguez, M.A.; Barna, M.G.; Gebhart, K.A.; Hand, J.L.; Adelman, Z.E.; Schichtel, B.A.; Collett, J.L., Jr.; Malm, W.C. Modeling the fate of atmospheric reduced nitrogen during the Rocky Mountain Atmospheric Nitrogen and Sulfur Study (RoMANS): Performance evaluation and diagnosis using integrated processes rate analysis. Atmos. Environ. 2011, 45, 223–234, doi:10.1016/j.atmosenv.2010.09.011.
[18]
Wesely, M.L. Parameterization of surface resistances to gaseous dry deposition in regional-scale numerical models. Atmos. Environ. 1989, 23, 1293–1304, doi:10.1016/0004-6981(89)90153-4.
[19]
Slinn, S.A.; Slinn, W.G.N. Predictions for particle deposition on natural waters. Atmos. Environ. 1980, 24, 1013–1016.
[20]
Pleim, J.E.; Clarke, J.F.; Finkelstein, P.L.; Cooter, E.J.; Ellestad, T.G.; Xiu, A.; Angevine, W.M. Comparison of Measured and Modeled Surface Fluxes of Heat, Moisture and Chemical Dry Deposition. In Air Pollution Modeling and Its Application, XI ed.; Plenum Press: New York, NY USA, 1996.
[21]
Pleim, J.E.; Xiu, A.; Finkelstein, P.L.; Clarke, J.F. Evaluation of a Coupled Land-Surface and Dry Deposition Model through Comparison to Field Measurements of Surface Heat, Moisture, and Ozone Fluxes. In Proceedings of the 12th Symposium on Boundary Layers and Turbulence, Vancouver, BC, Canada, 28 July-1 August 1997.
[22]
Morris, R.E.; Koo, B.; Piyachaturawat, P.; Stella, G.; McNally, D.; Loomis, C.; Chien, C.-J.; Tonnesen, G. Technical Support Document for VISTAS Emissions and Air Quality Modeling to Support Regional Haze State Implementation Plans (Final Report), March 2009. Available online: http://www.metro4-sesarm.org/vistas/data/RHR/Modeling/Reports/VISTASII_TSD_FinalReport_3-09.pdf (accessed on 29 December 2011).
[23]
Morris, R.E.; Kemball-Cook, S.; Sakulyanonyvittaya, T.; Parker, L.; Shah, T.; Nopmomngcol, U.; Piyachaturawat, P. Uinta Basin Air Quality Study (UBAQS) Technical Report (Final Report), June 2009. Available online: http://westernenergyalliance.org/wp-content/uploads/UBAQS_Final_Report_Jun30_2009.pdf (accessed on 29 December 2011).
[24]
Karamchandani, P.; Vijayaraghavan, K.; Bronson, R.; Chen, S.-Y.; Knipping, E.M. Development and application of a parallelized version of the Advanced Modeling System for Transport, Emissions, Reactions and Deposition of Atmospheric Matter (AMSTERDAM): 1. Model performance evaluation. Atmos. Poll. Res. 2010, 1, 260–270.
[25]
Morris, R.E.; Tai, E.; Sakulyanonyvittaya, T.; McNally, D.; Loomis, C. Model Performance Evaluation for the June-July 2006 Ozone Episode for the Denver 8-Hour Ozone State Implementation Plan (Final Report), August 2008. Available online: http://www.colorado.gov/airquality/documents/deno308/Denver_2006MPE_DraftFinal_Aug29_2008.pdf (accessed on 29 December 2011).
[26]
Stoeckenius, T.E.; Emery, C.A.; Shah, T.P.; Johnson, J.R.; Parker, L.K.; Pollack, A.K. Air Quality Modeling Study for the Four Corners Region (Final Report), June 2009. Available online: http://www.nmenv.state.nm.us/aqb/4C/Documents/FinalRepRev20090806.pdf (accessed on 29 December 2011).
[27]
Clarke, J.F.; Edgerton, E.S.; Martin, B.E. Dry deposition calculations for the clean air status and trends network. Atmos. Environ. 1997, 31, 3667–3678, doi:10.1016/S1352-2310(97)00141-6.
[28]
Meyers, T.P.; Finkelstein, P.; Clarke, J.; Ellestad, T.G.; Sims, P.F. A multilayer model for inferring dry deposition using standard meteorological measurements. J. Geophys. Res. 1998, 103, 22645–22661.
[29]
Environmental Protection Agency (EPA). Ambient Air Monitoring Strategy for State, Local, and Tribal Air Agencies, December 2008. Available online: http://www.epa.gov/ttn/amtic/monstratdoc.html (accessed on 29 December 2011).
[30]
Foken, T.; Dlugi, R.; Kramm, G. On the determination of dry deposition and emission of gaseous compounds at the biosphere-atmosphere interface. Meteorol. Z. 1995, 4, 91–118.
[31]
Kramm, G.; Dlugi, R. Modelling of the vertical fluxes of nitric acid, ammonia, and ammonium nitrate. J. Atmos. Chem. 1994, 18, 319–357, doi:10.1007/BF00712450.
[32]
Kramm, G.; Dlugi, R.; Dollard, G.J.; Foken, T.; Molders, N.; Muller, H.; Seiler, W.; Sievering, H. On the dry deposition of ozone and reactive nitrogen species. Atmos. Environ. 1995, 29, 3209–3231.
[33]
Wesely, M.L.; Hicks, B.B. A review of the current status of knowledge on dry deposition. Atmos. Environ. 2000, 34, 2261–2282, doi:10.1016/S1352-2310(99)00467-7.
