Journal of Atmospheric Chemistry

, Volume 60, Issue 2, pp 117–135 | Cite as

A 10-year study of background surface ozone concentrations on the island of Gozo in the Central Mediterranean

  • Martin Saliba
  • Raymond EllulEmail author
  • Liberato Camilleri
  • Hans Güsten


A 10-year study of surface ozone mixing ratios in the Central Mediterranean was conducted based on continuous ozone measurements from 1997 to 2006 by a background regional Global Atmospheric Watch (GAW) station on the island of Gozo. The mean annual maximum mixing ratio is of the order of 66 ppbv in April–May with a broad secondary maximum of 64 ppbv in July–September. No long-term increase or decrease in the background level of surface ozone could be observed over the last 10 years. This is contrary to observations made in the Eastern Mediterranean, where a slow decrease in the background ozone mixing ratio was observed over the past 7 years. Despite the very high average annual ozone mixing ratio exceeding 50 ppbv—in fact, the highest average background ozone mixing ratio ever measured in Europe—, the diurnal O 3 max/O 3 min index of <1.40 indicates that the island of Gozo is a good site for measuring background surface ozone. However, frequent photosmog events from June to September during the past 10 years with ozone mixing ratios exceeding 90 ppbv indicate that the Central Mediterranean is prone to long-range transport of air pollutants from Europe by northerly winds. This was particularly evident during the so-called “August heatwave” of the year 2003 when the overall ozone mixing ratio was 4.6 ppbv higher than the average of all other 9 months of August since 1997. Air mass back-trajectory analysis of the August 2003 photosmog episodes on Gozo confirmed that ozone pollution originated from the European continent. Regression analysis was used to analyse the 10-year data set in order to model the behaviour of the ozone mixing ratio in terms of the meteorological parameters of wind speed, relative humidity, global radiation, temperature, month of year, wind sector, atmospheric pressure, and time of day (predictors). Most of these predictors were found to significantly affect the ozone mixing ratios. From March to November, the monthly average of the AOT40 threshold value for the protection of crops and vegetation against ozone was constantly exceeded on Gozo during the past 10 years.


Ozone Mediterranean Gozo Long-range transport Forecast Statistical model AOT40 value 



We wish to thank Mr Saviour Porter from the Malta Meteorological Office, Malta International Airport as well as Mr Charles Yousif and Mr Mario Fsadni from the Institute of Energy Technology of the University of Malta for supplying the pressure and radiation measurements missing in our own data set.


  1. Altshuller, A.P., Bufalini, J.J.: Photochemical aspects of air pollution: a review. Environ. Sci. Technol. 5, 39–64 (1972). doi: 10.1021/es60048a001 CrossRefGoogle Scholar
  2. Ashmore, M., Fuhrer, J.: New directions: use and abuse of the AOT40 concept. Atmos. Environ. 34, 1157–1159 (2000). doi: 10.1016/S1352-2310(99)00529-4 CrossRefGoogle Scholar
  3. Ashmore, M., Emberson, L., Karlsson, P.E., Pleijel, H.: New directions: a new generation of ozone critical levels for the protection of vegetation in Europe. Atmos. Environ. 38, 2213–2214 (2004). doi: 10.1016/j.atmosenv.2004.02.029 CrossRefGoogle Scholar
  4. Black, E., Blackburn, M., Harrison, G., Hoskins, B., Methven, J.: Factors contributing to the summer 2003 European heatwave. Weather 59(8), 217–223 (2004)CrossRefGoogle Scholar
  5. Beck, J., Grennfelt, P.: Distribution of ozone over Europe. In: Borrell, P.M., Borrell, P., Cvitas, T., Seiler, W. (ed.) Proc. EUROTRAC Symp. 1992, pp. 43–58. SPB Academic, The Hague, The Netherlands (1993)Google Scholar
  6. Chetcuti, D., Buhagiar, A., Schembri, P.J., Ventura, F.: The climate of the Maltese Islands—a review, pp. 30–33. Malta University Press, Msida (1992)Google Scholar
  7. Corbett, J.J., Fishbeck, P.S., Pandis, S.N.: Global nitrogen and sulphur inventories for oceangoing ships. J. Geophys. Res. 104, 3457–3470 (1999). doi: 10.1029/1998JD100040 CrossRefGoogle Scholar
  8. Corbett, J.J., Fishbeck, P.S.: Emissions from ships. Science 298, 823–824 (1997). doi: 10.1126/science.278.5339.823 CrossRefGoogle Scholar
  9. Cristofanelli, P., Bonasoni, P., Carboni, G., Calzolari, F., Casarola, L., Zauli Sajani, S., et al.: Anomalous high ozone concentrations recorded at a high mountain station in Italy in summer 2003. Atmos. Environ. 41, 1383–1394 (2007). doi: 10.1016/j.atmosenv.2006.10.017 CrossRefGoogle Scholar
  10. Cvitas, T., Klasinc, L.: Measurement of tropospheric ozone in the Eastern Mediterranean. Boll. Geofisico 16, 521–527 (1993)Google Scholar
  11. Cvitas, T., Kezele, N., Klasinc, L., Lisac, J.: Tropospheric ozone measurements in Croatia. Pure Appl. Chem. 67, 1450–1453 (1995)Google Scholar
  12. Cvitas, T., Kezele, N., Klasinc, L.: Boundary layer ozone in Croatia. J. Atmos. Chem. 28, 125–134 (1997). doi: 10.1023/A:1005845232426 CrossRefGoogle Scholar
  13. De Santis, F.: New directions: will a new European vegetation ozone standard be fair to all European countries? Atmos. Environ. 33, 3873–3874 (1999). doi: 10.1016/S1352-2310(99)00110-7 CrossRefGoogle Scholar
  14. De Santis, F.: Reply to “Use and abuse of the AOT40 concept” by M. Ashmore and J. Fuhrer. Atmos. Environ. 34, 1158–1159 (2000). doi: 10.1016/S1352-2310(99)00530-0 CrossRefGoogle Scholar
  15. Dickerson, R.R., Delany, A.C.: Modification of a commercial gas filter Correlation CO Detector for enhanced sensitivity. J. Atmos. Ocean. Technol. 5, 424–431 (1988). doi: 10.1175/1520-0426(1988)005<0424:MOACGF>2.0.CO;2 CrossRefGoogle Scholar
  16. European Monitoring and Evaluation Programme (EMEP): Transboundary photooxidant air pollution in Europe: calculations of tropospheric ozone and comparison with observations, Report EMEP Meteorological Synthesizing Centre–West. NILU, Norway (1998), JulyGoogle Scholar
  17. EU Directive 2002/3 of the European Parliament and of the Council (11 Febr. 2002) relating to ozone in ambient air. Official Journal of the European Communities, Annex 1, 9th March 2002Google Scholar
  18. Fink, A.H., Brucher, T., Kruger, A., Leckebush, G.C., Pinto, J.G., Ulbrich, U.: The 2003 European summer heatwave and drought—synoptic diagnosis and impacts. Weather 59(8), 209–215 (2004)CrossRefGoogle Scholar
  19. Fischer, H., Kormann, R., Klüpfel, T., Gurk, C., Königstedt, R., Parchatka, U., Mühle, J., Rhee, T.S., Brenninkmeijer, C.A.M., Bonasoni, P., Sohl, A.: Ozone production and trace gas correlations during the June 2000 MINATROC intensive measurement campaign at Mt. Cimone. Atmos. Chem. Phys. 3, 725–738 (2003)Google Scholar
  20. Gerasopoulos, E., Kouvarakis, G., Vrekoussis, M., Kanakidou, M., Mihalopoulos, N.: Ozone variability in the marine boundary layer of the Eastern Mediterranean based on 7-year observations. J. Geophys. Res. 110(No. D15), D15309 (2005). doi: 10.1029/2005JD005991 CrossRefGoogle Scholar
  21. Güsten, H.: Formation, transport, and control of photochemical smog. In: Hutzinger, O. (ed.) The Handbook of Environmental Chemistry, Vol 4/ Part A—Air Pollution, pp. 53–106. Springer, Berlin, Germany (1986)Google Scholar
  22. Güsten, H., Heinrich, G., Mönnich, E., Sprung, D., Ramadan, A.B., EzzEl-Din, M.R.M., Ahmed, D.M., Hassan, G.K.Y.: On-line measurements of ozone surface fluxes. Part II: Surface-level ozone fluxes onto the Sahara desert. Atmos. Environ. 30, 911–918 (1996)CrossRefGoogle Scholar
  23. HYSPLIT 4 (HYbrid Single-Particle Lagrangian Integrated Trajectory) Model 1997. Web address:, NOAA Air Resources Laboratory, Silver Spring, MD, USA
  24. Jonson, J.E., Simpson, D., Fagerli, H., Solberg, S.: Can we explain the trends in European ozone levels? Atmos. Chem. Phys. 6, 51–66 (2006)Google Scholar
  25. Kallos, G., Kotroni, V., Lagouvardos, K., Papadopoulos, A.: On the long-range transport of air pollutants from Europe to Africa. Geophys. Res. Lett. 25, 619–622 (1998)CrossRefGoogle Scholar
  26. Kouvarakis, G., Tsigardis, K., Kanakidou, M., Mihalopoulos, N.: Temporal variations of surface regional background ozone over Crete island in the southeast Mediterranean. J. Geophys. Res. 105(No. D4), 4399–4407 (2000)CrossRefGoogle Scholar
  27. Kouvarakis, G., Vrekoussis, M., Mihalopoulos, N., Kourtidis, K., Rappenglueck, B., Gerasopoulos, E., Zerefos, C.: Spatial and temporal variability of tropospheric ozone in the boundary layer above the Aegean Sea (Eastern Mediterranean). J. Geophys. Res. 107(No. D18), 8137 (2002). doi: 10.1029/2000JD000081 CrossRefGoogle Scholar
  28. Lamb, H.H.: Malta’s sea breezes. Weather 10, 256–264 (1955)Google Scholar
  29. Lawrence, M.G., Crutzen, P.J.: Influence of NOx emissions from ships on tropospheric photochemistry and climate. Nature 402, 167–170 (1999)CrossRefGoogle Scholar
  30. Lelieveld, J., and 30 co-authors: Global air pollution crossroads over the Mediterranean. Science 298, 794–799 (2002)CrossRefGoogle Scholar
  31. Löye Pilot, M.D., Mihalopoulos, N., Kouvarakis, G., Markaki, Z., Oikonomou, C., Nolle, M., Ellul, R.: One-year data set of atmospheric deposition of Saharan dust and nutrients at Malta. ADIOS Report to European Commission. Deliverable No. 44. February (2004)Google Scholar
  32. Marmer, E., Langmann, B.: Impact of ship emissions on the Mediterranean summertime pollution and climate: a regional model study. Atmos. Environ. 39, 4659–4669 (2005)CrossRefGoogle Scholar
  33. Millan, M.M., Sanz, M.J., Salvador, R., Mantilla, E.: Atmospheric dynamics and ozone cycles related to nitrogen deposition in the western Mediterranean. Environ. Pollut. 118, 167–186 (2002)CrossRefGoogle Scholar
  34. Monks, P.S.: A review of the observations and origins of the spring ozone maximum. Atmos. Environ. 34, 3545–3561 (2000)CrossRefGoogle Scholar
  35. Nakicenovic, N.: IPCC Special Report on Emission Scenarios. A special report of working group III of the Intergovernmental Panel on Climate Change, p. 599. Cambridge University Press, Cambridge, UK (2000)Google Scholar
  36. Nolle, M., Ellul, R., Güsten, H., Heinrich, G.: Long term background ozone and carbon monoxide measurements on the Maltese Islands. Proceedings of 8th European Symposium on the Physico Chemical Behaviour of Atmospheric Pollutants. September 2001, Turin, Italy (2001)Google Scholar
  37. Nolle, M., Ellul, R., Heinrich, G., Güsten, H.: A long term study of background ozone concentrations in the Central Mediterranean—diurnal and seasonal variations on the island of Gozo. Atmos. Environ. 36, 1391–1402 (2002)CrossRefGoogle Scholar
  38. Nolle, M., Ellul, R., Ventura, F., Güsten, H.: A study of historical surface ozone measurements (1884–1900) on the island of Gozo in the central Mediterranean. Atmos. Environ. 39, 5608–5618 (2005)CrossRefGoogle Scholar
  39. Osborne, S.R., Johnson, D.W., Bauer, K.N., Wood, R.: Modification of the aerosol size distribution within exhaust plumes produced by diesel powered ships. J. Geophys. Res. 106(D9), 9827–9842 (2001)CrossRefGoogle Scholar
  40. Scheel, H.E., Aresbough, H., Geiss, H., Gormiscek, B., Granby, K., Haszpra, L., Klasinc, L., Kley, D., Laurila, T., Lindskog, A., Roemer, M., Schmitt, R., Simmond, P., Solberg, S., Toupande, G.: On the spatial distribution and seasonal variation of lower tropospheric ozone over Europe. J. Atmos. Chem. 28, 11–28 (1997)CrossRefGoogle Scholar
  41. Solberg, S., Coddeville, P., Forster, C., Hov, Ø., Orsolini, Y., Uhse, K.: European surface ozone in the extreme summer 2003. Atmos. Chem. Phys. Discuss. 5, 9003–9038 (2005)CrossRefGoogle Scholar
  42. United States Environmental Protection Agency Report No. 454/R-99-009, July 1999, Guideline for developing an ozone forecasting program. Research Triangle Park, NC 27711, USAGoogle Scholar
  43. Vingarzan, R.: A review of surface ozone background levels and trends. Atmos. Environ. 38, 3431–3442 (2004)CrossRefGoogle Scholar
  44. Vautard, R., Honore, C., Beekman, M., Rouil, L.: Simulation of ozone during the August 2003 heat wave and emission control scenarios. Atmos. Environ. 39, 2957–2967 (2005)CrossRefGoogle Scholar
  45. Weather in the Mediterranean: Vol 1 (2nd Edition), General Meteorology, Air Ministry, Meteorological Office, H.M.S.O. Code No. 40-142-1-62, UK (1962)Google Scholar
  46. WHO (World Health Organization) Report: Air Quality Guidelines for Europe. WHO Regional Publications, European Series No. 23; World Health Organization, Copenhagen (1987)Google Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Martin Saliba
    • 1
  • Raymond Ellul
    • 1
  • Liberato Camilleri
    • 2
  • Hans Güsten
    • 3
  1. 1.Department of PhysicsUniversity of MaltaMsidaMalta
  2. 2.Department of Statistics and Operations ResearchUniversity of MaltaMsidaMalta
  3. 3.Institut für Meteorologie und KlimaforschungForschungszentrum Karlsruhe/Universität KarlsruheKarlsruheGermany

Personalised recommendations