 |
| Titel |
Seasonal variability of dust in the eastern Mediterranean (Athens, Greece), through lidar measurements in the frame of EARLINET (2002-2012) |
| VerfasserIn |
Panos Kokkalis, Alex Papayannis, George Tsaknakis, RodElise Mamouri, Athina Argyrouli |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250076608
|
|
|
|
|
|
| Zusammenfassung |
| Aerosols play an important role in earth’s atmospheric radiation balance, which is enhanced
in areas where dust is mostly present (e.g. the Mediterranean region), as in the
case of the city of Athens. The focus of this paper is to provide a comprehensive
analysis of the seasonal variability of optical and geometrical properties, as well as the
mass concentration of Saharan dust over the city of Athens, Greece, for a 10-years
time period: 2002-2012 based on the laser remote sensing (lidar) technique. More
specifically, the aerosol optical properties concern the extinction and the backscatter
coefficient, as well as the lidar ratio, while the geometrical properties concern the
dust layer thickness and center of mass. The calculations of the aerosol extinction
coefficient and of the so-called lidar ratio (defined as the ratio of the aerosol extinction
coefficient over the aerosol backscatter coefficient) are made by using the Raman
lidar technique, only under cloud-free conditions. The calculation of the dust mass
concentration was retrieved by a applying a conversion factor (the so-called dust
extinction cross section; mean value of the order of 0.64 m2g-1) and by combining sun
photometric measurements and modeled dust loading values. Our data analysis
was based on monthly-mean values, and only in time periods under cloud-free
conditions and for lidar signals with signal to noise ratios (SNR) greater than 1.5
under dusty conditions. The mean value of the lidar ratio at 355 nm was found
to be 62±20sr, while the mean dust mass concentration was of the order of 240
μgm-3.
The data analyzed were obtained by systematic aerosol lidar measurements performed by
the EOLE Raman lidar system of the National Technical University of Athens (NTUA), in the
frame of the European Aerosol Research Lidar network (EARLINET). EOLE is able to
provide the vertical profiles of the aerosol backscatter (at 355, 532, 1064 nm) and extinction
coefficients (at 355 and 532 nm), as well as the water vapor mixing ratio, from
about 700 m up to 10000 m, with high temporal (< 5 min.) and spatial (7.5 m)
resolution.
Acknowledgements:
This research has been co-financed by the European Union (European Social Fund - ESF)
and Greek national funds through the Operational Program "Education and Lifelong
Learning" of the National Strategic Reference Framework (NSRF) - Research Funding
Program: Heracleitus II - Investing in knowledge society through the European
Social Fund. This research was also financially supported by ITARS (www.itars.net),
European Union Seventh Framework Programme (FP7/2007-2013): People, ITN
Marie Curie Actions Programme (2012-2016) under grant agreement no 289923. |
|
|
|
|
|
|