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Tracking urban particulate pollution
with Landsat images

The air pollution phenomenon in Athens-Greece is known as "the nephos" (the cloud) a name that underlines its visible character.Visibility impairment during pollution episodes is due to high burdens of aerosol particles in the atmosphere while the yellowish-brown colour of the cloud is due to high NO2 concentrations. In Athens, as in most densely populated urban areas, non-black particles are formed in the lowest part of the atmosphere as secondary aerosols (ammonium sulphates and nitrates).These particles have gained recently a high-priority in environmental reporting following wide spread concern about their health effects, which is mainly due to their small size (i.e., less than 3 microns that makes them respirable.The high spatial resolution TM optical sensor of the Landsat satellite could sense these small particles over Athens.

The application of an ad hoc image processing code to Landsat images allowed producing "Pollution maps" at urban scale. These maps interpreted in conjunction with modelling and ground measurements allowed to explain how the nephos spreads over the Athens basin at single but representative points in time:For example, the top pollution-map illustrates moderate turbidity levels during a late-summer day; the pollution forms a cloud in a "horseshoe" shape over the Athens basin. A lower-pollution island is formed inside the plume by the penetration of the sea breeze starting to develop at that time of the day.The denser part of the cloud is surrounding Mt. Pendeli and spreads towards the eastern coastline. The next two pollution-maps correspond to early summer conditions when pollution becomes denser from west to east and from south to north inside the basin but not particularly in the city centre.Mt. Imittos is covered by the plume, which continuous to spread towards the Messogia plain to the east of the basin.The last pollution-map illustrates that, during a typical springtime episode, the main pollution burden is confined to the basin with higher turbidity levels above and around the city centre. The dense pollution cloud is expanded, according to the wind regime, to the NE (Mt. Pendeli) and east of the basin (Mt. Ymittos).

Related Publications

  1. Sifakis N. (1991) Air pollution in Athens: Similarities of findings with remote sensing methods in 1967 and 1987. Ekistics, 58.

  2. Sifakis N., Deschamps P.Y. (1992) Mapping of Air Pollution Using SPOT Satellite Data, Photogrammetric Engineering and Remote Sensing, 58, 1433-1437.

  3. Sifakis N., Bildgen P., Gilg J.P. (1992) Use of the band 6 of Thematic Mapper to localise atmospheric-pollution clouds; the case of Athens (Greece). Pollution Atmosphérique, 133, 96-107 (in French).

  4. Sifakis N. (1995) Particulate pollution in urban areas: the case of Athens. Europe’s Environment: The Dobris Assessment, Chapter 10: The Urban Environment, D. Stanners and Ph. Bourdeau (ed.), European Environment Agency, Copenhagen, p. 269 (ISBN 92-826-5404-5).

  5. Sifakis N. (1995) Remote sensing of veils of atmospheric pollution and degradation of the environment in the region of Athens. Photo-interpretation: images aeriennes et spatiales, 33, 220-225 & 233-236.

  6. Sifakis N., Soulakellis N., Paronis D. (1998) Quantitative mapping of air pollution density using Earth observations: A new processing method and application on an urban area. International Journal of Remote Sensing, 19, 3289-3300.

  7. Sifakis N., Sarigiannis D., Asimakopoulos D., Bonetti A., Nicoloyanni E., Lointier M., Schafer C., Soulakellis N., Tombrou M. (1999)ICAROS: Integrated Computational Assessment Via Remote Observation System Using Satellite Earth Observations. Proc. HELECO'99 Environmental Technology for the 21st Century: Thessaloniki, 3-6 June 1999, 486-495.

  8. Sifakis N., Soulakellis N. A. (2000) Satellite Image Processing for Haze and Aerosol Mapping (SIPHA): Code description and presentation of results. Proc. of the IGARSS 2000, Honolulu, 24-28 July 2000, 222-224.

  9. Kanaroglou P.S., Soulakellis N.A. and Sifakis N.I. (2002) Improvement of Satellite Derived Pollution Maps with the Use of a Geostatistical Interpolation Method. Journal of Geographical Systems, 4, 193-208.

  10. K. SCHÄFER et al. (2002) THREE-DIMENSIONAL GROUND-BASED MEASUREMENTS OF URBAN AIR QUALITY TO EVALUATE SATELLITE DERIVED INTERPRETATIONS FOR URBAN AIR POLLUTION.Water, Air, and Soil Pollution: Focus 2: 91–102, 2002.

  11. D. A. SARIGIANNIS et al. (2002) ICAROS: AN INTEGRATED COMPUTATIONAL ENVIRONMENT FOR THE ASSIMILATION OF ENVIRONMENTAL DATA AND MODELS FOR URBAN AND REGIONAL AIR QUALITY. Water, Air, and Soil Pollution: Focus 2: 641–654, 2002.

  12. N. Sifakis, N. Soulakellis, D. Sarigiannis, M. Tombrou, K. Schäfer (2003) High Spatial Resolution Satellites as a Complement to Atmospheric Modelling and to Ground Measurements for Air-Quality Monitoring. SPIE Remote Sensing 2002, 23-27 September, Crete, Greece, Proc. of SPIE vol. 4882: 532-539.

  13. D. Sarigiannis, N. Soulakellis, N. I. Sifakis, M. Tombrou,K. Schäfer (2003) Multidisciplinary Data and Model Fusion: a Key to Integrated Air Quality Assessment.SPIE Remote Sensing 2002, 23-27 September, Crete, Greece, Proc. of SPIE vol. 4882: 520-531.

  14. Retalis A., Sifakis N., Grosso N., Paronis D., Sarigiannis D. (2003) Aerosol optical thickness retrieval from AVHRR images over the Athens urban area. IEEE International Geoscience & Remote Sensing Symposium (IGARSS) 2003, 21-25 July 2003, Toulouse, France, Proc. of IGARSS vol. IV:2182-2184.

  15. Sarigiannis D., Sifakis N., Soulakellis N., Schafer K., Tombrou M. (2003) A new Approach to environmental date fusion for integrated assessment of particulate matter loading and its effect on health in the urban environment. IEEE International Geoscience & Remote Sensing Symposium (IGARSS) 2003, 21-25 July 2003, Toulouse, France, Proc. of IGARSS vol. VII:4579-4581.

  16. Paronis D., Sifakis N. (2003) Satellite aerosol optical thickness retrieval over land with contrast reduction analysis using a variable window size. IEEE International Geoscience & Remote Sensing Symposium (IGARSS) 2003, 21-25 July 2003, Toulouse, France, Proc. of IGARSS vol. II:1276-1278.

  17. Sarigiannis D., Soulakellis N. and Sifakis N. (2004) Information Fusion for Computational Assessment of Air Quality and Health Effects, Photogr. Engin. & Remote Sensing, Vol. 70, No. 2, February 2004, pp. 235–245.

  18. Sarigiannis D., Sifakis N., Tombrou M., Dandou A. (2005) Backcasting of air pollution In Athens, Greece. Poster paper presented in the Urban Air Quality Int. Conference, 29-31 March 2005, Valencia, Spain.


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