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	<journal>
		<journal_title>Atmospheric Chemistry and Physics</journal_title>
		<journal_url>www.atmos-chem-phys.net</journal_url>
		<issn>1680-7316</issn>
		<eissn>1680-7324</eissn>
		<volume_number>9</volume_number>
		<issue_number>3</issue_number>
		<publication_year>2009</publication_year>
	</journal>
	<doi>10.5194/acp-9-849-2009</doi>
	<article_url>http://www.atmos-chem-phys.net/9/849/2009/</article_url>
	<abstract_html>http://www.atmos-chem-phys.net/9/849/2009/acp-9-849-2009.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys.net/9/849/2009/acp-9-849-2009.pdf</fulltext_pdf>
	<start_page>849</start_page>
	<end_page>864</end_page>
	<publication_date>2009-02-03</publication_date>
	<article_title content_type="html">Contribution of atmospheric processes affecting the dynamics of air pollution in South-Western Europe during a typical summertime photochemical episode</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>M. GonÃ§alves</name>
		</author>
		<author numeration="2" affiliations="2">
			<name>P. JimÃ©nez-Guerrero</name>
		</author>
		<author numeration="3" affiliations="1,2">
			<name>J. M. Baldasano</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Projects Engineering Department, Technical University of Catalonia, Barcelona, Spain</affiliation>
		<affiliation numeration="2" content_type="html">Barcelona Supercomputing Center-Centro Nacional de SupercomputaciÃ³n, Barcelona, Spain</affiliation>
	</affiliations>
	<abstract content_type="html">The southern Mediterranean region frequently experiences critical levels of
photochemical pollutants during summertime. In order to account for the
contribution of different atmospheric processes during this type of
episodes, the WRF-ARW/HERMES/CMAQ modelling system was applied with high
resolution (1 km&lt;sup&gt;2&lt;/sup&gt;, 33 sigma vertical layers, 1 h) to assess the
different dynamics in a coastal environment and an inland-continental zone:
the North-Eastern and Central Iberian Peninsula (NEIP and CIP,
respectively). The former is characterized by a very complex terrain, while
the latter behaves as a flat area, which clearly affects the pattern of
local flows. A representative type of photochemical pollution episode
(occurring over 78% of summer days) which occurred during 17â€“18 June,
2004 is selected as the study period. The CMAQ Integrated Process Rate
provides the hourly contributions of atmospheric processes to net O&lt;sub&gt;3&lt;/sub&gt;,
NO&lt;sub&gt;x&lt;/sub&gt; and NMVOCs concentrations. The O&lt;sub&gt;3&lt;/sub&gt; photochemical formation
occurs mainly in downwind areas from the main NO&lt;sub&gt;x&lt;/sub&gt; emission sources
during midday. At surface level it accounts for 50 to 75 Î¼g m&lt;sup&gt;&amp;minus;3&lt;/sup&gt; h&lt;sup&gt;&amp;minus;1&lt;/sup&gt;.
The urban areas and main roads, as main sources of NO&lt;sub&gt;x&lt;/sub&gt;
emissions, act as O&lt;sub&gt;3&lt;/sub&gt; sinks, quenching up to &amp;minus;200 Î¼g m&lt;sup&gt;&amp;minus;3&lt;/sup&gt; per
hour during the traffic circulation peaks. The O&lt;sub&gt;3&lt;/sub&gt; concentration
gradient generated, larger during daytime, increases the contribution of
diffusion processes to ground-level O&lt;sub&gt;3&lt;/sub&gt; (up to 200 Î¼g m&lt;sup&gt;&amp;minus;3&lt;/sup&gt; h&lt;sup&gt;&amp;minus;1&lt;/sup&gt;
fluxes, mainly from upper vertical layers). The maximum positive
contributions of gas-phase chemistry to O&lt;sub&gt;3&lt;/sub&gt; occur in the coastal domain
at high levels (around 500 to 1500 m a.g.l.), while in the continental domain
they take place in the whole atmospheric column under the PBL. The transport
of ozone precursors by advective flows determines the location of the
maximum O&lt;sub&gt;3&lt;/sub&gt; surface concentrations. The O&lt;sub&gt;3&lt;/sub&gt; chemical formation
involves the oxidation of less NMVOCs in the NEIP than in the CIP domains,
due to differences in chemical sensitivity between these areas. The dry
deposition is an important sink in the lowest layer of the model, together
with vertical diffusion flows. Finally, the contributions from cloud
processes, wet deposition and heterogeneous chemistry are negligible during
the whole episode, characterized by a high solar radiation and neither
precipitation nor cloudiness. This process analysis provides new
quantitative information about the origin of the peaks of O&lt;sub&gt;3&lt;/sub&gt; and its
precursors, aiding the design of abatement strategies in South-Western
Europe.</abstract>
	<references>
		<reference numeration="1" content_type="text"> % vor jede Referenz ArÃ©valo, G., Salvador, R., Gass´o, S., Millan, M., and Baldasano, J. M.: Application of a high-resolution emission model in Valencia Community (Spain), in: Air Pollution XII, edited by: BREBBIA WITpress, Rhodes, Greece, 14, 31â€“40, 2004. </reference>
		<reference numeration="2" content_type="text"> Baldasano, J. M., Cremades, L., and Soriano, C.: Circulation of Air Pollutants over the Barcelona Geographical Area in Summer, in: Proceedings of Sixth European Symposium Physico-Chemical Behaviour of Atmospheric Pollutants, Varese (Italy), 18â€“22 October, 1993, Report EUR 15609/1 EN, 474â€“479, 1994. </reference>
		<reference numeration="3" content_type="text"> Baldasano, J. M., GÃ¼ereca, P., LÃ³pez, E., GassÃ³, S., and JimÃ©nez-Guerrero, P.: Development of a high resolution (1 km&amp;times;1 km, 1 h) emission model for Spain: the High-Elective Resolution Modelling Emission System (HERMES), Atmos. Environ., 42, 7215â€“7233, 2008. </reference>
		<reference numeration="4" content_type="text"> Barros, N., Borrego, C., Toll, I., Soriano, C., JimÃ©nez, P., and Baldasano, J. M.: Urban Photochemical Pollution in the Iberian Peninsula: Lisbon and Barcelona Airsheds, J. Air Waste Manage., 53, 347â€“359, 2003. </reference>
		<reference numeration="5" content_type="text"> Byun, D. W. and Schere, K. L.: Review of the governing equations, computational algorithms and other components of the Models-3 Community Multiscale Air Quality (CMAQ) Modeling System, Appl. Mech. Rev., 59(2), 51â€“77, 2006. </reference>
		<reference numeration="6" content_type="text"> Colella, P. and Woodward, P. L.: The piecewise parabolic method (PPM) for gas-dynamical simulations, J. Comput. Phys., 54, 174â€“201, 1984. </reference>
		<reference numeration="7" content_type="text"> Coll, I., Pinceloup, S., Perros, P. E., Laverdet, G., and Le Bras, G.: 3D analysis of high ozone production rates observed during the ESCOMPTE campaign, Atmos. Res., 74, 477â€“505, 2005. </reference>
		<reference numeration="8" content_type="text"> Cousin, F., Tulet, P., and Rosset, R.: Interaction between local and regional pollution during ESCOMPTE 2001: impact on surface ozone concentrations (IOP2a and 2b), Atmos. Res., 74, 117â€“137, 2005. </reference>
		<reference numeration="9" content_type="text"> Cros, B., Durand, P., Cachier, H., Drobinski, Ph., FrÃ©jafon, E., Kottmeier, C., Perros, P. E., Peuch, V.-H., Ponche, J.-L., Robin, D., Sa\&quot;&amp;#x0131;d, F., Toupance, G., and Wortham, H.: The ESCOMPTE program: an overview, Atmos. Res., 69, 241â€“279, 2004. </reference>
		<reference numeration="10" content_type="text"> Dufour, A., Amodei, M., Ancellet, G., and Peuch, V.-H.: Observed and modelled chemical weather during ESCOMPTE, Atmos. Res., 74, 161â€“189, 2005. </reference>
		<reference numeration="11" content_type="text"> EC: Directive 2008/50/EC of the European Parliament and of the Council of 21~May 2008 on ambient air quality and cleaner air for Europe, Official Journal of the European Union, 11 June 2008, 44~pp., 2008. </reference>
		<reference numeration="12" content_type="text"> Gipson, L. G.: Science Algorithms of the EPA Models-3 Community Multiscale Air Quality (CMAQ) Modeling System: process analysis, EPA/600/R-99/030, US-EPA, online available at: http://www.epa.gov/asmdnerl/CMAQ/CMAQscienceDoc.html, 37~pp., 1999. </reference>
		<reference numeration="13" content_type="text"> Gery, M. W., Whitten, G. Z., Killus, J. P., and Dodge, M. C.: A photochemical kinetics mechanism for urban and regional scale computer modeling, J. Geophys. Res., 94(12), 925â€“956, 1989. </reference>
		<reference numeration="14" content_type="text"> Hauglustaine, D. A. and Brasseur, G. P.: Evolution of tropospheric ozone under anthropogenic activities and associated radiative forcing on climate, J. Geophys. Res., 106, 32337â€“32360, 2001. </reference>
		<reference numeration="15" content_type="text"> Hertel, O., Berkowicz, R., Christensen, J., and Hov, O.: Test of two numerical schemes for use in atmospheric transport-chemistry models, Atmos. Environ., 27A, 2591â€“2611, 1993. </reference>
		<reference numeration="16" content_type="text"> Hogrefe, C., Lynn, B., Rosenzweig, C., Goldberg, R., Civerolo, K., Ku, J.-Y., Rosenthal, J., Knowlton, K., and Kinney, P. L.: Utilizing CMAQ process analysis to understand the impacts of climate change on ozone and particulate matter, in: 4th Annual CMAS Models-3 Users&apos; Conference, 26â€“28 September 2005, Chapel Hill, NC, USA, 2005. </reference>
		<reference numeration="17" content_type="text"> Huang, J. P., Fung, J., Zhang, Y., Lau, A., and Qin, Y.: Process analysis of different synoptic patterns of O3 episodes in Hong Kong, in: 86th Annual Meeting of AMS, 28 Januaryâ€“3 February 2006, Atlanta, GA, USA, 2006. </reference>
		<reference numeration="18" content_type="text"> Jang, J. C., Jeffries, H. E., Byun, D., and Pleim, J. E.: Sensitivity of ozone to model grid resolution â€“ I. Application of high-resolution regional acid deposition model, Atmos. Environ., 21, 3085â€“3100, 1995a. </reference>
		<reference numeration="19" content_type="text"> Jang, J. C., Jeffries, H. E., and Tonnesen, S.: Sensitivity of ozone to model grid resolution â€“ II. Detailed process analysis for ozone chemistry, Atmos. Environ., 29, 3101â€“3114, 1995b. </reference>
		<reference numeration="20" content_type="text"> Jeffries, H. E. and Tonnesen, S.: A comparison of two photochemical reaction mechanisms using mass balance and process analysis, Atmos. Environ., 28, 2991â€“3003, 1994. </reference>
		<reference numeration="21" content_type="text"> Jiang, G., Lamb, B. and Westberg, H.: Using back trajectories and process analysis to investigate photochemical ozone production in the Puget Sound region, Atmos. Environ., 37, 1489â€“1502, 2003. </reference>
		<reference numeration="22" content_type="text"> JimÃ©nez, P., Baldasano, J. M., and Dabdub, D.: Comparison of photochemical mechanisms for air quality modelling, Atmos. Environ., 37, 4179â€“4194, 2003. </reference>
		<reference numeration="23" content_type="text"> JimÃ©nez, P., Jorba, O., Parra, R., and Baldasano, J. M.: Evaluation of MM5-EMICAT2000-CMAQ performance and sensitivity in complex terrain: High-resolution application to the northeastern Iberian Peninsula, Atmos. Environ., 40, 5056â€“5072, 2005. </reference>
		<reference numeration="24" content_type="text"> JimÃ©nez, P., Lelieveld, J., and Baldasano, J. M.: Multiscale modelling of air pollutants dynamics in the northwestern Mediterranean basin during a typical summertime episode, J. Geophys. Res., 111, D18306, doi:10.1029/2005JD006516, 2006. </reference>
		<reference numeration="25" content_type="text"> JimÃ©nez-Guerrero, P., Jorba, O., Baldasano, J. M., and GassÃ³, S.: The use of a modeling system as a tool for air quality management: Annual high-resolution simulations and evaluation, Sci. Total Environ., 390, 323â€“340, doi:10.1016/j.scitotenv.2007.10.025, 2008. </reference>
		<reference numeration="26" content_type="text"> Jonson, J. E., Simpson, D., Fagerli, H., and Solberg, S.: Can we explain the trends in European ozone levels?, Atmos. Chem. Phys., 6, 51â€“66, 2006. </reference>
		<reference numeration="27" content_type="text"> Jorba, O., PÃ©rez, C., Rocadenbosch, F., and Baldasano, J. M.: Cluster Analysis of 4-Day Back Trajectories Arriving in the Barcelona Area (Spain) from 1997 to 2002, J. Appl. Meteorol., 43(6), 887â€“901, 2004. </reference>
		<reference numeration="28" content_type="text"> Lawrence, M. G., Crutzen, P. J., Rasch, P. J., Eaton, B. E., and Mahowald, N. M.: A model for studies of tropospheric photochemistry: description, global distributions and evaluation, J. Geophys. Res., 104, 26245â€“26277, 1999. </reference>
		<reference numeration="29" content_type="text"> Lawrence, M. G., Rasch, P. J., von Kuhlmann, R., Williams, J., Fischer, H., de Reus, M., Lelieveld, J., Crutzen, P. J., Schultz, M., Stier, P., Huntrieser, H., Heland, J., Stohl, A., Forster, C., Elbern, H., Jakobs, H., and Dickerson, R. R.: Global chemical weather forecasts for field campaign planning: predictions and observations of large-scale features during MINOS, CONTRACE, and INDOEX, Atmos. Chem. Phys., 3, 267â€“289, 2003. </reference>
		<reference numeration="30" content_type="text"> Lelieveld, J., Berresheim, H., Borrmann, S., Crutzen, P. J., Dentener, F. J., Fischer, H., Feichter, J., Flatau, P. J., Heland, J., Holzinger, R., Korrmann, R., Lawrence, M. G., Levin, Z., Markowicz, K. M., Mihalopoulos, N., Minikin, A., Ramanathan, V., de Reus, M., Roelofs, G. J., Scheeren, H. A., Sciare, J., Schlager, H., Schultz, M., Siegmund, P., Steil, B., Stepahanou, E. G., Stier, P., Traub, M., Warneke, C., Williams, J., and Zieris, H.: Global air pollution crossroads over the Mediterranean, Science, 298, 794â€“799, 2002. </reference>
		<reference numeration="31" content_type="text"> Michalakes, J., Dudhia, J., Gill, D., Henderson, T., Klemp, J., Skamarock, W., and Wang, W.: TheWeather Research and Forecasting Model: software architecture and performance, in: Proceedings of the Eleventh ECMWF Workshop on the Use of High Performance Computing in Meteorology, edited by: Zwiefhofer, W. and Mozdzynski, G., World Scientific, European Centre for Medium-Range Weather Forecasts, UK, 156â€“168, 2004. </reference>
		<reference numeration="32" content_type="text"> MillÃ¡n, M., Salvador, R., Mantilla, E., and ArtÃ­Ã±ano, B.: Meteorology and photochemical air pollution in southern Europe: Experimental results from EC research projects, Atmos. Environ., 30, 1909â€“1924, 1996. </reference>
		<reference numeration="33" content_type="text"> MillÃ¡n, M., Salvador, R., Mantilla, E., and Kallos, G.: Photo-oxidant dynamics in the Mediterranean basin in summer: results from European research projects, J. Geophys. Res., 102, 8811â€“8823, 1997. </reference>
		<reference numeration="34" content_type="text"> O&apos;Neil, S. and Lamb, B.: Intercomparison of the Community Multiscale Air Quality Model and CALGRID using Process Analysis, Environ. Sci. Technol., 39, 5742â€“5753, 2005. </reference>
		<reference numeration="35" content_type="text"> Ortega, S., Soler, M. R., Beneito, J., and Pino, D.: Evaluation of two ozone air quality modelling systems, Atmos. Chem. Phys., 4, 1389â€“1398, 2004. </reference>
		<reference numeration="36" content_type="text"> Parra, R., GassÃ³, S., an Baldasano, J. M.: Estimating the biogenic emissions of non-methane volatile organic compounds from the North western Mediterranean vegetation of Catalonia, Spain, Sci. Total Environ., 329, 241â€“259, 2004. </reference>
		<reference numeration="37" content_type="text"> Parra, R., JimÃ©nez, P., and Baldasano, J. M.: Development of the high spatial resolution EMICAT2000 emission model for air pollutants from the north-eastern Iberian Peninsula (Catalonia, Spain), Environ. Pollut., 140, 200â€“219, 2006. </reference>
		<reference numeration="38" content_type="text"> PÃ©rez, C., Sicard, M., Jorba, O., ComerÃ³n, A., and Baldasano, J. M.: Summertime re-circulations of air pollutants over the north-eastern Iberian coast observed from systematic EARLINET lidar measurements in Barcelona, Atmos. Environ., 38, 3983â€“4000, 2004. </reference>
		<reference numeration="39" content_type="text"> Roelofs, G. J., Scheeren, H. A., Heland, J., Ziereis, H., and Lelieveld, J.: A model study of ozone in the eastern Mediterranean free troposphere during MINOS (August 2001), Atmos. Chem. Phys., 3, 1199â€“1210, 2003. </reference>
		<reference numeration="40" content_type="text"> San JosÃ©, R., PÃ©rez, J. L., Pleguezuelos, C., Camacho, F., and GonzÃ¡lez, R. M.: MM5-CMAQ air quality modeling process analysis: Madrid case, Air pollution X, Ecology and the Environment vol. 53, ISBN:1-85312-916-X., C. A. BREBBIA, Wessex Institute of Technology, UK and University of the West of England, Bristol, UK, 2002. </reference>
		<reference numeration="41" content_type="text"> Skamarock, W. C., Klemp, J. B., Dudhia, J., Gill, D. O., Barker, D. M., Wang, W., and Powers, J. G.: A Description of the Advanced Research WRF Version 2, NCAR Technical note NCAR/TN-468+STR, NCAR, 2005. </reference>
		<reference numeration="42" content_type="text"> Sillman, S. and He, D.: Some theoretical results concerning O&lt;sub&gt;3&lt;/sub&gt;-NO&lt;sub&gt;x&lt;/sub&gt;-VOC chemistry and NO&lt;sub&gt;x&lt;/sub&gt;-VOC indicators, J. Geophys. Res., 107(D22), 4659, doi:10.1029/2001JD001123, 2002. </reference>
		<reference numeration="43" content_type="text"> Soriano, C., Baldasano, J. M., Buttler, W. T., and Moore, K.: Circulatory Patterns of Air Pollutants within the Barcelona Air Basin in a Summertime situation: Lidar and Numerical Approaches, Bound.-Lay. Meteorol., 98(1), 33â€“55, 2001. </reference>
		<reference numeration="44" content_type="text"> Taghavi, M., Cautenet, S., and Foret, G.: Simulation of ozone production in a complex circulation region using nested grids, Atmos. Chem. Phys., 4, 825â€“838, 2004. </reference>
		<reference numeration="45" content_type="text"> Toll, I. and Baldasano, J. M.: Modeling of photochemical air pollution in the Barcelona area with highly disaggregated anthropogenic and biogenic emissions, Atmos. Environ., 34, 3060â€“3084, 2000. </reference>
		<reference numeration="46" content_type="text"> US-EPA: Guideline for Regulatory Application of the Urban Airshed Model, US EPA Report No. EPA-450/4-91-013, Office of Air and Radiation, Office of Air Quality Planning and Standards, Technical Support Division, Research Triangle Park, North Carolina, USA, 1991. </reference>
		<reference numeration="47" content_type="text"> US-EPA: Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM$_2.5$, and Regional Haze, EPA-454/B-07-002, US Environmental Protection Agency Office of Air Quality Planning and Standards Air Quality Analysis Division Air Quality Modeling Group Research Triangle Park, North Carolina, USA, April 2007, 262~pp., 2007. </reference>
		<reference numeration="48" content_type="text"> Vautard, R., Bessagnet, B., Chin, M., and Menut, L.: On the contribution of natural Aeolian sources to particulate matter concentrations in Europe: Testing hypotheses with a modelling approach, Atmos. Environ. 39, 3291â€“3303, 2005. </reference>
		<reference numeration="49" content_type="text"> Zhang, Y., Vijayaraghavan, K., Huang, J., and Jacobson, M. Z.: Probing into Regional O&lt;sub&gt;3&lt;/sub&gt; and PM Pollution: A 1-year CMAQ Simulation and Process Analysis over the United States, in: 14th Joint Conference on the Applications of Air Pollution Meteorology with the Air and Waste Management Association, 28 Janauryâ€“2 February 2006, Atlanta, GA, USA, 2006. </reference>
	</references>
</article>

