Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station
Optical and geometrical characteristics of cirrus clouds over Thessaloniki, Greece (40.6° N, 22.9° E) have been determined from the analysis of lidar and radiosonde measurements performed during the period from 2000 to 2006. Cirrus clouds are generally observed in a mid-altit...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2007-11-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/7/5519/2007/acp-7-5519-2007.pdf |
| _version_ | 1818807439596716032 |
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| author | E. Giannakaki D. S. Balis V. Amiridis S. Kazadzis |
| author_facet | E. Giannakaki D. S. Balis V. Amiridis S. Kazadzis |
| author_sort | E. Giannakaki |
| collection | DOAJ |
| description | Optical and geometrical characteristics of cirrus clouds over Thessaloniki, Greece (40.6° N, 22.9° E) have been determined from the analysis of lidar and radiosonde measurements performed during the period from 2000 to 2006. Cirrus clouds are generally observed in a mid-altitude region ranging from 8.6 to 13 km, with mid-cloud temperatures in the range from −65° to −38°C. The cloud thickness generally ranges from 1 to 5 km and 38{%} of the cases studied have thickness between 2 and 3 km. The retrieval of optical depth and lidar ratio of cirrus clouds is performed using three different methods, taking into account multiple scattering effect. The mean optical depth is found to be 0.31±0.24 and the corresponding mean lidar ratio is 30±17 sr following the scheme of Klett-Fernald method. Sub-visual, thin and opaque cirrus clouds are observed at 3%, 57% and 40% of the measured cases, respectively. A comparison of the results obtained between the three methods shows good agreement. The multiple scattering errors of the measured effective extinction coefficients range from 20 to 60%, depending on cloud optical depth. The temperature and thickness dependencies on optical properties have also been studied in detail. A maximum mid-cloud depth of ~3.5 km is found at temperatures around ~−47.5°C, while there is an indication that optical depth and mean extinction coefficient increases with increasing mid-cloud temperature. A correlation between optical depth and thickness was also found. However, no clear dependence of the lidar ratio values on the cloud temperature and thickness was found. |
| first_indexed | 2024-12-18T19:25:41Z |
| format | Article |
| id | doaj.art-5597a19983b54b1ebd73d121114093a5 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-18T19:25:41Z |
| publishDate | 2007-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-5597a19983b54b1ebd73d121114093a52022-12-21T20:55:53ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242007-11-0172155195530Optical and geometrical characteristics of cirrus clouds over a Southern European lidar stationE. GiannakakiD. S. BalisV. AmiridisS. KazadzisOptical and geometrical characteristics of cirrus clouds over Thessaloniki, Greece (40.6° N, 22.9° E) have been determined from the analysis of lidar and radiosonde measurements performed during the period from 2000 to 2006. Cirrus clouds are generally observed in a mid-altitude region ranging from 8.6 to 13 km, with mid-cloud temperatures in the range from −65° to −38°C. The cloud thickness generally ranges from 1 to 5 km and 38{%} of the cases studied have thickness between 2 and 3 km. The retrieval of optical depth and lidar ratio of cirrus clouds is performed using three different methods, taking into account multiple scattering effect. The mean optical depth is found to be 0.31±0.24 and the corresponding mean lidar ratio is 30±17 sr following the scheme of Klett-Fernald method. Sub-visual, thin and opaque cirrus clouds are observed at 3%, 57% and 40% of the measured cases, respectively. A comparison of the results obtained between the three methods shows good agreement. The multiple scattering errors of the measured effective extinction coefficients range from 20 to 60%, depending on cloud optical depth. The temperature and thickness dependencies on optical properties have also been studied in detail. A maximum mid-cloud depth of ~3.5 km is found at temperatures around ~−47.5°C, while there is an indication that optical depth and mean extinction coefficient increases with increasing mid-cloud temperature. A correlation between optical depth and thickness was also found. However, no clear dependence of the lidar ratio values on the cloud temperature and thickness was found.http://www.atmos-chem-phys.net/7/5519/2007/acp-7-5519-2007.pdf |
| spellingShingle | E. Giannakaki D. S. Balis V. Amiridis S. Kazadzis Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station Atmospheric Chemistry and Physics |
| title | Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station |
| title_full | Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station |
| title_fullStr | Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station |
| title_full_unstemmed | Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station |
| title_short | Optical and geometrical characteristics of cirrus clouds over a Southern European lidar station |
| title_sort | optical and geometrical characteristics of cirrus clouds over a southern european lidar station |
| url | http://www.atmos-chem-phys.net/7/5519/2007/acp-7-5519-2007.pdf |
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