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| Titel |
Transport of dust and anthropogenic aerosols across Alexandria, Egypt |
| VerfasserIn |
H. El-Askary, R. Farouk, C. Ichoku, M. Kafatos |
| 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 ; 27, no. 7 ; Nr. 27, no. 7 (2009-07-21), S.2869-2879 |
| Datensatznummer |
250016596
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2869-2009.pdf |
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| Zusammenfassung |
| The flow of pollutants from Europe and desert dust to Europe from the Sahara
desert both affects the air quality of the coastal regions of Egypt. As
such, measurements from both ground and satellite observations assume great
importance to ascertain the conditions and flow affecting the Nile Delta and
the large city of Alexandria. We note that special weather conditions
prevailing in the Mediterranean Sea result in a westerly wind flow pattern
during spring and from North to South during the summer. Such flow patterns
transport dust-loaded and polluted air masses from the Sahara desert and
Europe, respectively, through Alexandria, and the Nile Delta in Egypt. We
have carried out measurements acquired with a ground- based portable sun
photometer (Microtops II) and the satellite-borne TERRA/Moderate
Resolution Imaging Spectroradiometer (MODIS) sensor during the periods of
October 1999–August 2001 and July 2002–September 2003. These measurements
show a seasonal variability in aerosol optical depth (AOD) following these
flow patterns. Maximum aerosol loadings accompanied by total precipitable
water vapor (W) enhancements are observed during the spring and summer
seasons. Pronounced changes have been observed in the Ångström
exponent (α) derived from ground-based measurements over Alexandria
(31.14° N, 29.59° E) during both dust and pollution periods. We have
followed up the observations with a 3-day back-trajectories model to trace
the probable sources and pathways of the air masses causing the observed
aerosol loadings. We have also used other NASA model outputs to estimate the
sea salt, dust, sulfates and black carbon AOD spatial distributions during
different seasons. Our results reveal the probable source regions of these
aerosol types, showing agreement with the trajectory and Ångström
exponent analysis results. It is confirmed that Alexandria is subjected to
different atmospheric conditions involving dust, pollution, mixed aerosols
and clean sky. |
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