Assessment of atmospheric processes driving ozone variations in the subtropical North Atlantic free troposphere

Atmospheric Chemistry and Physics

Volumn 13, Issue 4, 2013, Pages 1973-1998

  Cuevas, E ^a   Gonzalez Y ^a   Rodriguez S ^a   Guerra, J C ^b   Gomez Pelaez A J ^a   Alonso Perez S ^a,c   Bustos, J ^a   Milford, C ^a,d  

^a Izana Atmospheric Research Centre IARC   (Spain)

^b UNIVERSIDAD DE LA LAGUNA   (Spain)

^c INSTITUTE OF ENVIRONMENTAL ASSESSMENT AND WATER RESEARCH   (Spain)

^d UNIVERSITY OF HUELVA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

AIR MASS; BOUNDARY LAYER; CARBON MONOXIDE; CLIMATOLOGY; CORRELATION; DIURNAL ACTIVITY; OZONE; PHOTOCHEMISTRY; POTENTIAL VORTICITY; SEASONAL VARIATION; STRATOSPHERE; SUBTROPICAL REGION; TROPOSPHERE;

ATLANTIC OCEAN; ATLANTIC OCEAN (NORTH);

EID: 84874447030     PISSN: 16807316     EISSN: 16807324     Source Type: Journal    
DOI: 10.5194/acp-13-1973-2013     Document Type: Article

References (115)

1. Akritidis, D., Zanis, P., Pytharoulis, I., Mavrakis, A., and Kara-costas, Th.: A deep stratospheric intrusion event down to the earth's surface of the megacity of Athens, Meteorol. Atmos. Phys., 109, 9-18, doi:10.1007/s00703-010- 0096-6, 2010.
2. Alonso-Pérez, S., Cuevas, E., Querol, X., Viana, M., and Guerra, J.: Impact of the Saharan dust outbreaks on the ambient levels of total suspended particles (TSP) in the marine boundary layer (MBL) of the Subtropical Eastern North Atlantic Ocean, Atmos. Environ., 41, 9468-9480, 2007. (Pubitemid 350161356)
3. Alonso-Pérez, S., Cuevas, E., Pérez, C., Querol, X., Baldasano, J., Draxler, R., and de Bustos, J.: Trend changes of African air-mass intrusions in the marine boundary layer over the subtropical Eastern North Atlantic region in winter, Tellus B, 63B, 255-265, 2011.
4. Andrade, C., Trigo, R., Freitas, M., Gallego, M., Borges, P., and Ramos, A.: Comparing historic records of storm frequency and the North Atlantic Oscillation (NAO) chronology for the Azores region, The Holocene, 18, 745-754, 2008.
5. Andrey, J., Gil, M., Alonso-Pérez, S., Parrondo, C., Redondas, A., and Cuevas, E.: Tropospheric ozone under Saharan dust: a statistical study on vertical distribution, in: International Aerosol Conference, number 873, Helsinki (Finland), 29 August-3 September, 2010.
6. Appenzeller, C., Davies, H., and Norton, W.: Fragmentation of stratospheric intrusions, J. Geophys. Res., 101, 1435-1456, 1996.
7. Appenzeller, C., Weiss, A., and Staehelin, J.: North Atlantic oscillation modulates total ozone winter trends, Geophys. Res. Lett., 27, 1131-1134, 2000. (Pubitemid 32035658)
8. Auvray, M. and Bey, I.: Long-range transport to Europe: seasonal variations and implications for the European ozone budget, Geophys. Res. Lett., 110, D11303, doi:10.1029/2004JD005503, 2005. (Pubitemid 41282238)
9. Balkanski, Y. J., Jacob, D., Gardner, G., Graustein, W., and Turekian, K.: Transport and residence times of tropospheric aerosols inferred from a global three-dimensional simulation of 210Pb, J. Geophys. Res., 98, 20573-20586, 1993.
10. Beekman, M., Ancellet, G., and Megie, G.: Climatology of tropo-spheric ozone in southern Europe and its relation to potential vor-ticity, J. Geophys. Res., 99, 12841-12853, 1994.
11. Berkowtiz, C., Daum, P., Spicer, C., and Busness, K.: Synoptic patterns associated with the flux of excess ozone to the western North Atlantic, J. Geophys. Res., 101, 28923-28933, 1996.
12. Bonasoni, P., Evangelisti, F., Bonafe, U., Ravegnani, F., Calzo-lari, F., Stohl, A., Tositti, L., Tubertini, O., and Colombo, T.: Stratospheric ozone intrusion episodes recorded at Mt. Cimone during the VOTALP project: case studies, Atmos. Environ., 34, 1355-1365, 2000. (Pubitemid 30089684)
13. Bonasoni, P., Cristofanelli, P., Calzolari, F., Bonafè, U., Evangelisti, F., Stohl, A., Zauli Sajani, S., van Dingenen, R., Colombo, T., and Balkanski, Y.: Aerosol-ozone correlations during dust transport episodes, Atmos. Chem. Phys., 4, 1201-1215, doi:10.5194/acp-4-1201-2004, 2004. (Pubitemid 39337649)
14. Chiapello, I., Moulin, C., and Prospero, J.: Understanding the long-term variability of African dust transport across the Atlantic as recorded in both Barbados surface concentrations and large-scale Total ozone Mapping Spectrometer (TOMS) optical thickness, J. Geophys. Res., 110, D18S10, doi:10.1029/ 2004JD005132, 2005. (Pubitemid 41582675)
15. Chin, M., Jacob, D., Munger, J., Parrish, D. D., and Dod-dridge, B.: Relationship of ozone and carbon monoxide over North America, J. Geophys. Res., 99, 14565-14573, doi:10.1029/2004JD005132, 1994.
16. Cooper, O. and Parrish, D.: Air Pollution Export from and Emport to North America: Experimental Evidence, The Handbook of Environmental Chemistry, vol. 4G, Springer, New York, 2004.
17. Cooper, O., Moody, J., Parrish, D., Trainer, M., Holloway, J., Ry-erson, T., Hüler, G., Fehsenfeld, F., Oltmans, S., Evans, M., and Evans, M. J.: Air Pollution Export from and Emport to North America: Experimental Evidence, vol. 4G, Springer, New York, 2002.
18. Creilson, J. K., Fishman, J., and Wozniak, A. E.: Intercontinental transport of tropospheric ozone: a study of its seasonal variability across the North Atlantic utilizing tropospheric ozone residuals and its relationship to the North Atlantic Oscillation, At-mos. Chem. Phys., 3, 2053-2066, doi:10.5194/acp-3-2053-2003, 2003.
19. Cristofanelli, P., Bonasoni, P., Tositti, L., Bonafè, U, Calzolari, F. Evangelisti, F., Sandrini, S., and Stohl, A.: A 6-year analysis of stratospheric intrusions and their influence on ozone at Mt. Ci-mone (2165 m above sea level), J. Geophys. Res., 111, D03306, doi:10.1029/2005JD006553, 2006.
20. Cuevas, E.: Estudio del Comportamiento del Ozono Troposférico en el Observatorio de Izaña (Tenerife) y su Relación con la Dinámica Atmosférica, Ph. D. thesis, Facultad de Ciencias F́sicas, Universidad Complutense de Madrid, 1995.
21. Cuevas, E. and Rodŕguez, J.: Statistics of cutoff lows over the North Atlantic (in Spanish), in: Proceedings Tercera Asamblea Hispano-Portuguesa de Geodesia y Geofisica, Valencia, Spain, 4-8 February, 2002, 1-3, Comision Española de Geodesia y Ge-ofisica, Edited by Editorial UPV, Valencia, Spain, 2002.
22. Cuevas, E., Díaz, A., and Martín, F.: Atmospheric Carbon Dioxide Concentration at Izaña BAPMoN Observatory, Canary Islands, 1984-1990, in: Proceedings 19th ITM on Air Pollution Modeling and its Applications, NATO/CCMS, Ierapetra, Greece, 29 September-4 October 1991, 45-46, edited by: van Dop, H. and Kallos, G., Plenum Press, New York, USA, 1992.
23. Cuevas, E., Diamantino, V., and Sancho, J.: Stratosphere-Troposphere Exchange events over North Atlantic subtropical region, in: Proc. Second Asamblea Hispano Portuguesa de Geode-sia y Geofisica, edited by Instituto Geofisico do Infante D. Luis (Portugal), S11-16, 451-452, Lagos (Portugal), 8-12 February, 2000.
24. Danielsen, E.: Stratospheric-tropospheric exchange based on radioactivity ozone and potential vorticity, J. Atmos. Sci., 25, 502-518, 1968.
25. de Reus, M., Dentener, F., Thomas, A., Borrmann, S. J. S., and Lelieveld, J.: Airborne observations of dust aerosol over the North Atlantic Ocean during ACE 2-indications for heterogeneous ozone destruction, J. Geophys. Res., 105, 15263-15275, doi:10.1029/2000JD900164, 2000.
26. Dickerson, R., Doddridge, B., Kelley, P., and Rhoads, K.: Large scale pollution of the atmosphere over the remote Atlantic Ocean: evidence from Bermuda, J. Geophys. Res., 10, 8945-8952, 1995. (Pubitemid 26439579)
27. Draxler, R. and Rolph, G.: HYSPLIT (Hybrid Single-Particle La-grangian Integrated Trajectory) Model access via NOAA ARL READY, Tech. rep., NOAA Air Resources Laboratory, Silver Spring, MD, available at: http://www.arl.noaa.gov/ ready/hysplit4.html (last access: March 2012), 2003.
28. Duncan, B. N. and Bey, I.: A modeling study of the export pathways of pollution from Europe: seasonal and interan-nual variations (1987-1997), J. Geophys. Res., 109, D08301, doi:10.1029/2003JD004079, 2004. (Pubitemid 38893012)
29. Eckhardt, S., Stohl, A., Beirle, S., Spichtinger, N., James, P., Forster, C., Junker, C., Wagner, T., Platt, U., and Jennings, S. G.: The North Atlantic Oscillation controls air pollution transport to the Arctic, Atmos. Chem. Phys., 3, 1769-1778, doi:10.5194/acp-3-1769-2003, 2003.
30. Evan, A. T., Heidinger, A. K., and Knippertz, P.: Analysis of winter dust activity off the coast of West Africa using a new 24-year over-water advanced very high resolution radiometer satellite dust climatology, J. Geophys. Res., 111, D12210, doi:10.1029/2005JD006336, 2006. (Pubitemid 44687634)
31. Fishman, J. and Balok, A. E.: Calculation of daily tropospheric ozone residuals using TOMS and empirically improved SBUV measurements: application to an ozone pollution episode over the Eastern United States, J. Geophys. Res., 104, 30319-30340, 1999.
32. Fishman, J. and Crutzen, P.: The Origin of ozone in the troposphere, Nature, 274, 855-858, 1978. (Pubitemid 9004048)
33. Fishman, J., Wozniak, A. E., and Creilson, J. K.: Global distribution of tropospheric ozone from satellite measurements using the empirically corrected tropospheric ozone residual technique: Identification of the regional aspects of air pollution, Atmos. Chem. Phys., 3, 893-907, doi:10.5194/acp-3-893-2003, 2003.
34. Fleming, Z., Monks, P., and Manning A.: Untangling the influence of air-mass history in interpreting observed atmospheric composition, Atmos. Res., 104-105, 1-39, 2012.
35. Font, I.: El Tiempo Atmosférico de las Islas Canarias, Servicio Me-teorológico Nacional, Serie A, no. 26, INM, Madrid, 1956.
36. Gerasopoulos, E., Zanis, P., Stohl, A., Zerefos, C., Papastefanou, C., Ringer, W., Tobler, L., Hübener, S., Gäggeler, H., Kanter, H., Tositti, L., and Sandrini, S.:A climatology of 7Be at four high-altitude stations at the Alps and the Northern Apennines, Atmos. Environ., 35, 6347-6360, 2001. (Pubitemid 33070512)
37. Gilge, S., Plass-Duelmer, C., Fricke, W., Kaiser, A., Ries, L., Buch-mann, B., and Steinbacher, M.: Ozone, carbon monoxide and nitrogen oxides time series at four alpine GAW mountain stations in central Europe, Atmos. Chem. Phys., 10, 12295-12316, doi:10.5194/acp-10-12295-2010, 2010.
38. Gillett, N., Graf, H., and Osborn, T. J.: The North Atlantic Oscillation: climatic significance and environmental impact, in: Geophys. Monogr. Ser., edited by: Hurrell, J., Kushnir, Y, Ot-tersen, G. and Visbeck, M., vol. 134, AGU, Washington, DC, 193-210, 2003.
39. Gómez-Peláez, A., Ramos, R., and Pérez-delaPuerta, J.: Methane and Carbon Dioxide Continuous Measurements at Izaña GAW station (Spain), in: 13th WMO/IAEA Meeting Experts on Carbon Dioxide, other Greenhouse gases, and Related Tracer Measurements Techniques, edited by: Miller, J., World Meteorological Organization (TD No. 1359), Boulder, Colorado, USA, 19-22 September, 2005, World Meteorological Organization, available at: ftp://ftp.wmo.int/Documents/PublicWeb/arep/gaw/gaw168.pdf (last access: February 2013), 180-184, 2006.
40. Gómez-Peláez, A. J., Ramos, R., Cuevas, E., and Gómez-Trueba, V.: 25 years of continuous CO2 and CH4 measurements at Izaña Global GAW mountain station: annual cycles and interannual trends; Proceedings of the "Symposium on Atmospheric Chemistry and Physics at Mountain Sites (ACP Symposium 2010, 8-10 June 2010, Interlaken, Switzerland)", available at: http://www.maiolica.ch/publications/ACP- Symposium-Abstracts.pdf (last access: February 2013), 157-159, 2010.
41. Gómez-Peláez, A. J., Ramos, R., Gomez-Trueba, V., Novelli, P. C., and Campo-Hernandez, R.: A statistical approach to quantify uncertainty in carbon monoxide measurements at the Izaña global GAW station: 2008-2011, Atmos. Meas. Tech. Discuss., 5, 6949-6989, doi:10.5194/amtd-5-6949- 2012, 2012.
42. Graustein, W. and Turekian, K.: 7Be and 210Pb indicate an upper troposphere source for elevated ozone in the summertime subtropical free troposphere of the Eastern North Atlantic, Geophys. Res. Lett., 23, 539-542, 1996.
43. Güsten, H., Heinrich, G., Mönnich, E., Sprung, D., Weppner, J., Ramadan, A. B., Ezz El-Din, M. R. M., Ahmed, D. M., and Hassan, G. K. Y.: On-line measurements of ozone surface fluxes, II, surface level ozone fluxes onto the Sahara desert, Atmos. Environ., 30, 911-918, 1996. (Pubitemid 26038719)
44. Hegarty, J., Mao, H., and Talbot, R.: Synoptic influences on springtime tropospheric O3 and CO over the North American export region observed by TES, Atmos. Chem. Phys., 9, 3755-3776, doi:10.5194/acp-9-3755-2009, 2009.
45. Honrath, R. E., Owen, R. C., and Val Martin, M. E. A.: Regional and hemispheric impacts of anthropogenic and biomass burning emissions on summertime CO and ozone in the North Atlantic lower free troposphere, J. Geophys. Res., 109, D24310, doi:10.1029/2004JD005147, 2004. (Pubitemid 40345253)
46. Hopke, P., Zhou, L., and Poirot, R.: Reconciling trajectory ensemble receptor model results with emissions, Environ. Sci. Technol., 39, 7980-7983, 2005.
47. Hoskins, B. J., McIntyre, M., and Robertosn, A.: On the use and significance of isentropic potential vorticity maps, Q. J. Roy. Me-teorol. Soc., 111, 877-946, 1985.
48. Hurrell, J. W. and Dickson, R. R.: Climate variability over the North Atlantic. Marine Ecosystems and Climate Variation: The North Atlantic, edited by: Stenseth, N. C., Ottersen, G., Hurrell, J. W., and Belgrano, A., Oxford University Press, 15-31, 2004.
49. Hurrell, J., Kushnir, Y., Ottersen, G., and Visbeck, M.: The North Atlantic Oscillation: Climate Significance and Environmental Impact, Geophysical Monograph Series, 134, American Geophysical Union, Washington DC, USA, 2003.
50. James, P., Stohl, A., Foster, C., Eckhard, S., Seibert, P., and Frank, A.: A 15-years climatology of stratosphere-troposphere exchange with a Lagrangian particle dispersion model: 2. Mean climate and seasonal variability, J. Geophys. Res., 108, 8522, doi:10.1029/2002JD002636, 2003.
51. Jonson, J. E., Simpson, D., Fagerli, H., and Solberg, S.: Can we explain the trends in European ozone levels?, Atmos. Chem. Phys., 6, 51-66, doi:10.5194/acp-6-51-2006, 2006. (Pubitemid 43263647)
52. Junge, C.: Global ozone budget and exchange between stratosphere and troposphere, Tellus, 14, 363-377, 1962.
53. Kasibhatla, P., Levy II, H., Klonecki, A., and Chameides, W. L.: Three-dimensional view of the large-scale tropospheric ozone distribution over the North Atlantic Ocean during summer, J. Geophys. Res., 101, 29305-29316, 1996.
54. Kentarchos, A., Roelofs, G., Lelievel, J., and Cuevas, E.: On the origin of elevated surface ozone concentrations at Izaña Observatory, Tenerife during late March 1996, Geophys. Res. Lett., 27, 3699-3702, 2000.
55. Lelieveld, J. and Dentener, F.: What controls tropospheric ozone?, J. Geophys. Res., 105, 3531-3551, 2000.
56. Levy, H. I.: Normal atmosphere: large radical and formaldehyde concentrations predicted, Science, 173, 141-143, 1971.
57. Levy, H. I., Mahlman, J., Moxim, W., and Liu, S.: Tropospheric ozone: the role of transport, J. Geophys. Res., 90, 3753-3772, 1985.
58. Li, Q., Jacob, D., Bey, I., Palmer, P., Duncan, B. N., Field, B. D., Martin, R. V., Fiore, A. M., Yantosca, R. M., Parrish, D. D., Sim-monds, P. G., and Oltmans, S.: Transatlantic transport of pollution and its effects on surface ozone in Europe and North America, J. Geophys. Res., 107, 4166, doi:10.1029/2001JD001422, 2002a. (Pubitemid 43197337)
59. Li, Q., Jacob, D., Fairlie, T., Liu, H., Yantosca, R., and Martin, R.: Stratospheric versus pollution influences on ozone at Bermuda: reconciling past analyses, J. Geophys. Res., 107, 4611, doi:10.1029/2002JD002138, 2002b. (Pubitemid 44793788)
60. Logan, J.: Tropospheric ozone: seasonal behavior, trends, and antro-pogenic influence, J. Geophys. Res., 90, 10463-10482, 1985.
61. Logan, J., Staehelin, J., Megretskaia, I., Cammas, J., Thouret, V., Claude, H., De Backer, H., Steinbacher, M., Scheel, H., Stübi, R., Fröhlich, M., Derwent, R.: Changes in ozone over Europe: Analysis of ozone measurements from sondes, regular aircraft (MOZAIC) and alpine surface sites, J. Geophys. Res., 117, D09301, doi:10.1029/2011JD016952, 2012.
62. London, J. and Liu, S.: Long-term tropospheric and lower stratospheric ozone variations from ozonesonde observations, J. At-mos. Terr. Phys., 54, 599-625, 1992.
63. Mao, H., Talbot, R., Troop, D., Johnson, R., Businger, S., and Thompson, A. M.: Smart balloon observations over the North Atlantic: ozone data analysis and modeling, J. Geophys. Res., 111, 599-625, doi:10.1029/2005JD006507, 2006. (Pubitemid 47260850)
64. Millán, 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, 8811-8823, 1997.
65. Mitchel, J.: The greenhouse effect and climate change, Rev. Geo-phys., 27, 115-139, 1989.
66. Moody, J L., Davenport, J. C., Merrill, J. T., Oltmans, S. J., Parrish, D. D., Holloway, J. S., Levy II, H., Forbes, G. L., Trainer, M., and Buhr, M.: Meteorological mechanisms for transporting ozone over the western North Atlantic Ocean: a case study for August 24-29, J. Geophys. Res 101, 29213-29227, 1996.
67. Nienerowski, K.: Qualitatssicherungs-Handbuch des UBA-Messnetzes, UBA Texte 28/04, Handbook for quality assurance for the measurement network for the Federal Environmental Agency, Umweltbundesamt, Berlin, Germany, June, 2004.
68. Nieto, R., Gimeno, L., Ribera, P., Gallego, D., Garća, R., and Hernández, E.: Effects of the North Atlantic Oscillation on the spatial distribution of cut-off low (COL) systems in the Northern Hemisphere, in: Proceedings of the AGU Chapman Conference "The North Atlantic Oscillation", Vigo, Spain, 28 November-1 December, available at: http://xtide.ldeo.columbia.edu/∼visbeck/nao/poster/(last access: October, 2012), 2000.
69. Nieto, R., Gimeno, L., de la Torre, L., Ribera, P., Gallego, D., Garća-Herrera, R., Garća, J., Núñez, M., Redaño, A., and Lorente, J.: Climatological features of cut-off low systems in the Northern Hemisphere, J. Climate, 18, 3085-3103, 2005. (Pubitemid 41461344)
70. Oltmans, S. and Levy II, H.: Seasonal cycle of surface ozone over the Western North Atlantic, Nature, 358, 392-394, 1992.
71. Oltmans, S. and Levy II, H.: Surface ozone measurements from a global network, Atmos. Environ., 28, 9-24, 1994.
72. Oltmans, S., Levy II, H., Harris, J., Merrill, J., Moody, J., Lath-rop, J., Cuevas, E., Trainer, M., O'Neill, M., Prospero, J., Vömel, H., and Johnson, B.: Summer and spring ozone profiles over the North Atlantic from ozonesonde measurements, J. Geo-phys. Res., 101, 29179-29200, 1996.
73. Oltmans, S., Lefohn, A., Harris, J., Galbally, I., Scheel, H., Bodeker, G., Brunke, E., Claude, H., Tarasick, D., Johnson, B., Simmonds, P., Shadwick, D., Anlauf, K., Hayden, K., Schmidlin, F., Fujimoto, T., Akagi, K., Meyer, C., Nichol, S., Davies, J., Redondas, A., and Cuevas, E.: Long-term changes in tropospheric ozone, Atmos. Environ., 40, 3156-3173, 2006.
74. Oltmans, S., Lefohn, A., Shadwick, D., Harris, J., Scheel, H. Gal-bally, I., Tarasick, D., Johnson, B., Brunke, E., Claude, H., Zeng, G., Nichol, S., Schmidlin, F., Davies, J., Cuevas, E., Re-dondas, A., Naoe, H., Nakano, T., and Kawasato, T.: Recent tro-pospheric ozone changes-A pattern dominated by slow or no growth, Atmos. Environ., 67, 331-351, 2013.
75. Ordóñez, C., Brunner, D., Staehelin, J., Hadjinicolaou, P., Pyle, J., Jonas, M., Wernli, H., and Prevot, A. S. H.: Strong influence of lowermost stratospheric ozone on lower tropospheric background ozone changes over Europe, Geophys. Res. Lett., 34, L07805, doi:10.1029/2006GL029113, 2007. (Pubitemid 46964243)
76. Owen, R. C., Cooper, O. R., Stohl, A., and Honrath, R. E.: An analysis of the mechanisms of North American pollutant transport to the Central North Atlantic lower free troposphere, J. Geophys. Res., 111, D23S58, doi:10.1029/2006JD007062, 2006. (Pubitemid 47260852)
77. Parrish, D., Holloway, J. S., Trainer, M., Murphy, P., Forbes, G., and Fehsenfeld, F.: Export of North American ozone pollution to the North Atlantic Ocean, Science, 259, 1436-1439, doi:10.1126/science.259.5100.1436, 1993.
78. Parrish, D. D., Holloway, J. S., and Jakoubek, R. E. A.: Mixing of anthropogenic pollution with stratospheric ozone: a case study from the North Atlantic wintertime troposphere, J. Geophys. Res., 105, 24363-24374, 2000.
79. Pausata, F. S. R., Pozzoli, L., Vignati, E., and Dentener, F. J.: North Atlantic Oscillation and tropospheric ozone variability in Europe: model analysis and measurements intercomparison, At-mos. Chem. Phys., 12, 6357-6376, doi:10.5194/acp-12-6357-2012, 2012.
80. Poirot, R. and Wishinski, P.: Visibility, sulphate and air mass history associated with the summertime aerosol in Northern Vermont, Atmos. Environ., 20, 1457-1469, 1986. (Pubitemid 16063481)
81. Prather, M., Gauss, M., and Berntsen, T. E. A.: Fresh air in the 21st century?, Geophys. Res. Lett., 30, 1100, doi:10.1029/2002GL016285, 2003.
82. Prospero, J. and Carlson, T.: Saharan air outbreaks over the tropical North Atlantic, Pageoph., 119, 677-691, doi:10.1029/2002GL016285, 1981.
83. Prospero, J., Schmitt, R., Cuevas, E., Savoie, D., Graustein, W., Turekian, K., Volz-Thomas, A., Díaz, A., Oltmans, S., and Levy, H.: Temporal variability of ozone and aerosols in the free troposphere over the Eastern North Atlantic, Geophys. Res. Letts., 22, 2925-2928, 1995. (Pubitemid 26443476)
84. Raes, F., VanDingenen, R., Cuevas, E., VanVelthoven, P. F. J., and Prospero, J. M.: Observations of aerosols in the free troposphere and marine boundary layer of the subtropical Northeast Atlantic: discussion of processes determining their size distribution, J. Geophys. Res., 102, 21315-21328, 1997.
85. Ramanathan, V., Cicerone, R., Singh, H. B., and Kiehl, J.: Trace gas trends and their potential role in climate change, J. Geophys. Res., 90, 5547-566, 1985. (Pubitemid 15526986)
86. Rao, T. N., Kirkwood, S., Arvelius, J., von der Gathen, P., and Kivi, R.: Climatology of UTLS ozone and the ratio of ozone and potential vorticity over northern Europe, J. Geophys. Res., 108, 4703, doi:10.1029/2003JD003860, 2003.
87. Reiter, R., Munzert, K., Kanter, H., and Poetzl, K.: Cosmogenic ra-dionuclides and ozone at a mountain station at 3.0 km a.s.l., Tech. Rep., Arc. Met. Geoph.Biocl., Ser. B, 32, 131-160, Garmisch-Partenkirchen, Germany, doi:10.1007/BF02273971, 1983.
88. Rodŕguez, S., Torres, C., Guerra, J., and Cuevas, E.: Transport pathways of ozone to marine and free-troposphere sites in Tenerife, Canary Islands, Atmos. Environ., 38, 4733-4747, 2004. (Pubitemid 38987672)
89. Rodŕguez, S., Alastuey, A., Alonso-Pérez, S., Querol, X., Cuevas, E., Abreu-Afonso, J., Viana, M., Pérez, N., Pandolfi, M., and de la Rosa, J.: Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer, At-mos. Chem. Phys., 11, 6663-6685, doi:10.5194/acp-11-6663-2011, 2011.
90. Rolph, G.: Real-time Environmental Applications and Display System (READY), Tech. rep., NOAA Air Resources Laboratory, Silver Spring, M. D., available at: http://www.arl.noaa.gov/ready/hysplit4.html (last access: September 2012), 1983.
91. Scheel, H.-E.: Ozone climatology studies for the Zugspitze and neighboring sites in the German Alps, edited by: Lindskog, A., TOR-2 Final Report, EUROTRAC-2 ISS, 134-139, GSF Research Center, Munich, Germany, 1983.
92. Schmitt, R. and Carretero, P.: Ozone in the Free Troposphere Over The North Atlantic: Production and Long-Range Transport, edited by Hov,Ø., EUROTRAC-2, German Research Center for Environmental Health (GmbH), Munich, Germany, 1992.
93. Schuepbach, E., Friedli, T., Zanis, P, Monks, P., and Penkett, S.: State space analysis of trends and seasonalities of lower free tropospheric ozone (1988-1997) at the high elevation site at Jungfraujoch, J. Geophys. Res., 106, 20413-20427, 2001.
94. Shapiro, M., Hampel, T., and Krueger, A.: The arctic tropopause fold, Mon. Weather Rev., 115, 444-454, 1987.
95. Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Av-eryt, K., Tignor, M., and Miller, H. (Eds.): IPCC AR4 WG1, Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK and New York, NY, USA, 2007.
96. Sprenger, M. and Wernli, H.: A northern hemispheric climatology of cross-tropopause exchange for the ERA15 time period (1979-1993), J. Geophys. Res., 108, 8521, doi:10.1029/2002JD002636, 2003.
97. Staehelin, J. and Poberaj, C.: Long-term Tropospheric ozone Trends: a Critical Review, vol. 33, Advances in Global Change Research, Climate Variability and Extremes during the Past 100 Years, IV, edited by: Bronniman, S., Luterbacher, J., Ewen, T., Diaz, H, Stolarski, R., Neu, U., Springer, Geneva, Switzerland, 2008.
98. Stohl, A.: A1-year Lagrangian "climatology" of airstreams in the Northern Hemisphere troposphere and lowermost stratosphere, J. Geophys. Res., 106, 7263-7279, 2001.
99. Stohl, A. and Trickl, T.: A textbook example of long-range transport: simultaneous observation of ozone maxima of stratospheric and North American origin in the free troposphere over Europe, J. Geophys. Res., 104, 30445-30462, 1999.
100. Stohl, A., Spichtinger-Rakowsky, N., Bonasoni, P., Feldmann, H., Memmesheimer, M., Scheel, H., Trickl, T., Hübener, S., Ringer, W., and Mandl, M.: The influence of stratospheric intrusions on alpine ozone concentrations, Atmos. Environ., 34, 1323-1354, 2000.
101. Stohl, A., Eckhardt, S., Forster, C., James, P., and Spichtinger, N.: On the pathways and timescales of intercontinental air pollution transport, J. Geophys. Res., 107, 4684, doi:10.1029/2001JD001396, 2002.
102. Tarasova, O., Elansky, N., Kuznetsov, G., Kuznetsova, I., and Senik, I.: Impact of air transport on seasonal variations and trends of surface ozone at Kislovodsk High Mountain stations, J. At-mos. Chem., 45, 245-259, doi:10.1029/2002JD002636, 2003. (Pubitemid 36874549)
103. Tarasova, O. A., Senik, I. A., Sosonkin, M. G., Cui, J., Staehe-lin, J., and Prévôt, A. S. H.: Surface ozone at the Caucasian site Kislovodsk High Mountain Station and the Swiss Alpine site Jungfraujoch: data analysis and trends (1990-2006), At-mos. Chem. Phys., 9, 4157-4175, doi:10.5194/acp-9-4157-2009, 2009.
104. Thompson, A.: The oxidizing capacity of the Earth's atmosphere: probable past and future changes, Science, 256, 1157-1165, 1992.
105. Tiao, G., Box, G., and Hamming, W.: Analysis of Los Angeles photochemical smog data: a statistical overview, J. Air Poll. Control Assoc., 25, 260-268, 1975.
106. Tripathi, O. P., Jennings, S. G., O'Dowd, C. D., Coleman, L., Lein-ert, S., O'Leary, B., Moran, E., O'Doherty, S., and Spain, T. G.: Statistical analysis of eight surface ozone measurement series for various sites in Ireland, J. Geophys. Res., 115, 85-89, doi:10.1029/2010JD014040, 2010.
107. Turekian, K. K., Nozaki, Y., and Benninger, L. K.: Geochemistry of atmospheric radon and radon products, Annu. Rev. Earth Planet. Sci., 5, 227-255, 1977.
108. Val Martin, M., Honrath, R. E., Owen, R. C., and Lapina, K.: Large-scale impacts of anthropogenic pollution and boreal wildfires on the nitrogen oxides over the central North Atlantic region, J. Geo-phys. Res., 113, D17308, doi:10.1029/2007JD009689, 2008.
109. Viezee, W. and Singh, H. B.: The distribution of beryllium-7 in the troposphere, implications on stratosphere/tropospheric air exchange, Geophys. Res. Lett., 7, 805-808, 1980.
110. Vingarzan, R.: A review of surface ozone background levels and trends, Atmos. Environ., 38, 3431-3442, 2004. (Pubitemid 38648812)
111. Wallace, J. and Gutzler, D. S.: Teleconnections in the geopoten-tial height field during the Northern Hemisphere winter, Mon. Weather Rev., 109, 784-812, 1981.
112. Wernli, H. and Bourqui, M.: A Lagrangian "1-year climatology" of (deep) cross-tropopause exchange in the extrat-ropical Northern Hemisphere, J. Geophys. Res., 107, 4021, doi:10.1029/2001JD000812, 2002.
113. WMO: Meteorology a Three-Dimensional Science: Second Session of the Commission for Aerology, WMO Bulletin IV(4), Tech. rep., NOAA Air Resources Laboratory, Geneva, 1957.
114. Yienger, J. J., Klonecki, A. A., Levy II, H., Moxim, W. J., and Carmichael, G. R.: An evaluation of chemistry's role in the winter-spring ozone maximum found in the northern mid-latitude free troposphere, J. Geophys. Res., 104, 3655-3667, doi:10.1029/1998JD100043, 1999. (Pubitemid 29298438)
115. Zanis, P., Schuepbach, E., Gäggeler, H.W., Hübener, S., and To-bler, L.: Factors controlling beryllium-7 at Jungfraujoch in Switzerland, Tellus B, Vol. 51, 4, 789-805, 1999. (Pubitemid 30039669)