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| Titel |
Five-years of atmospheric aerosol number size distribution measurements in Eastern Mediterranean |
| VerfasserIn |
Nikolaos Kalivitis, Giorgos Kouvarakis, Aikaterini Bougiatioti, Iasonas Stavroulas, Alfred Wiedensohler, Nikolaos Mihalopoulos |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250099996
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| Publikation (Nr.) |
 EGU/EGU2014-15860.pdf |
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| Zusammenfassung |
| The first long term measurements of atmospheric particle size distributions from the Eastern
Mediterranean region are reported. Atmospheric aerosol number size distributions have been
measured at the environmental research station of University of Crete at Finokalia, Crete,
Greece (35°20´ N, 25°40´ E, 250m a.s.l) on a continuous base since 2008. A custom built
(TROPOS type) scanning mobility particle sizer (SMPS) is used covering size ranges from 8
to 900 nm. The system is humidity controlled so that relative humidity is kept below 40%
most of the time.
Throughout the measuring period the average number concentration of the particles in the
studied size range was found to be 2354 ± 1332 cm-3 (median of 2098 cm-3). Maximum
concentrations are observed during summer while minimum during winter, reflecting the
effectiveness of the removal processes in the region. Clear annual circles are found for the
number concentrations of nucleation, Aitken and accumulation mode particles.
Nucleation mode is presenting different pattern from the other two modes, with the
highest concentrations during winter (and March) and the lowest during summer.
New particle formation events are more frequently observed during March and
October.
The number size distributions present different seasonal patterns. During summer, unimodal
distributions centering on the lower end of the accumulation mode size range are dominant in
our observations. The prevailing meteorology characterized by the Etesian winds
(Meltemi) and the lack of precipitation along the trajectory results to the arrival of
well mixed air masses at Finokalia, carrying aged aerosol mainly from central and
Eastern Europe. Regarding the other seasons, the shape of the distributions is more
variable and strongly dependent on the air mass history: When the air masses are of
marine origin or precipitation has affected them, the size distributions are mainly
bimodal (peaking both in Aitken and in Accumulation mode). These distributions
are representative of the background marine conditions at Finokalia. Unimodal
distributions can be observed as well during the rest of the seasons depending on
whether aged anthropogenic aerosol reach Crete before being removed from the
atmosphere or not. The nucleation mode is observed mainly when new particle
formation occurs and rarely can it be attributed to combustion processes or other
sources. |
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