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| Titel |
Optical characteristics of desert dust over the East Mediterranean during summer: a case study |
| VerfasserIn |
D. Balis, V. Amiridis, S. Kazadzis, A. Papayannis, G. Tsaknakis, S. Tzortzakis, N. Kalivitis, M. Vrekoussis, M. Kanakidou, N. Mihalopoulos, G. Chourdakis, S. Nickovic, C. Pérez, J. Baldasano, M. Drakakis |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 24, no. 3 ; Nr. 24, no. 3 (2006-05-19), S.807-821 |
| Datensatznummer |
250015513
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| Publikation (Nr.) |
 copernicus.org/angeo-24-807-2006.pdf |
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| Zusammenfassung |
| High aerosol optical depth (AOD) values, larger than 0.6, are systematically
observed in the Ultraviolet (UV) region both by sunphotometers and lidar
systems over Greece during summertime. To study in more detail the
characteristics and the origin of these high AOD values, a campaign took
place in Greece in the frame of the PHOENICS (Particles of Human Origin
Extinguishing Natural solar radiation In Climate Systems) and EARLINET
(European Aerosol Lidar Network) projects during August–September of 2003,
which included simultaneous sunphotometric and lidar measurements at three
sites covering the north-south axis of Greece: Thessaloniki, Athens and
Finokalia, Crete. Several events with high AOD values have been observed
over the measuring sites during the campaign period, many of them
corresponding to Saharan dust. In this paper we focused on the event of
30 and 31 August 2003, when a dust layer in the height
range of 2000-5000 m, progressively affected all three stations. This layer
showed a complex behavior concerning its spatial evolution and allowed us to
study the changes in the optical properties of the desert dust particles
along their transport due to aging and mixing with other types of aerosol.
The extinction-to-backscatter ratio determined on the 30 August
2003 at Thessaloniki was approximately 50 sr, characteristic for rather
spherical mineral particles, and the measured color index of 0.4 was within
the typical range of values for desert dust. Mixing of the desert dust with
other sources of aerosols resulted the next day in overall smaller and less
absorbing population of particles with a lidar ratio of 20 sr. Mixing of
polluted air-masses originating from Northern Greece and Crete and Saharan
dust result in very high aerosol backscatter values reaching
7 Mm-1 sr-1 over Finokalia. The Saharan dust observed over Athens
followed a different spatial evolution and was not mixed with the boundary
layer aerosols mainly originating from local pollution. |
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