气候变化领域集成服务门户(CCPortal): Variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes

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DOI	10.5194/acp-20-4427-2020
	Variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes
	Voudouri K.A.; Giannakaki E.; Komppula M.; Balis D.
发表日期	2020
ISSN	1680-7316
起始页码	4427
结束页码	4444
卷号	20 期号:7
英文摘要	Measurements of geometrical and optical properties of cirrus clouds, performed with a multi-wavelength PollyXT Raman lidar during the period 2008 to 2016, are analysed. The measurements were performed with the same instrument, during sequential periods, in three places at different latitudes, Gwal Pahari (28.43-N, 77.15-E; 243ma.s.l.) in India, Elandsfontein (26.25-S, 29.43-E; 1745ma.s.l.) in South Africa and Kuopio (62.74-N, 27.54-E; 190ma.s.l.) in Finland. The lidar dataset was processed by an automatic cirrus cloud masking algorithm, developed in the frame of this work. In the following, we present a statistical analysis of the lidar-retrieved geometrical characteristics (cloud boundaries, geometrical thickness) and optical properties of cirrus clouds (cloud optical depth, lidar ratio, ice crystal depolarisation ratio) measured over the three areas that correspond to subtropical and subarctic regions as well as their seasonal variability. The effect of multiple scattering from ice particles to the derived optical products is also considered and corrected in this study. Our results show that cirrus layers, which have a noticeable monthly variability, were observed between 6.5 and 13 km, with temperatures ranging from ° 72 to ° 27-C. The observed differences on cirrus clouds geometrical and optical properties over the three regions are discussed in terms of latitudinal and temperature dependence. The latitudinal dependence of the geometrical properties is consistent with satellite observations, following the pattern observed with CloudSat, with decreasing values towards the poles. The geometrical boundaries have their highest values in the subtropical regions, and overall, our results seem to demonstrate that subarctic cirrus clouds are colder, lower and optically thinner than subtropical cirrus clouds. The dependence of cirrus cloud geometrical thickness and optical properties on mid-cirrus temperatures shows a quite similar tendency for the three sites but less variability for the subarctic dataset. Cirrus clouds are geometrically and optically thicker at temperatures between ° 45 and ° 35-C, and a second peak is observed at lower temperatures-° 70-C for the subarctic site. Lidar ratio values also exhibit a pattern, showing higher values moving toward the poles, with higher mean values observed over the subarctic site. The dependency of the mid-cirrus temperatures on the lidar ratio values and the particle depolarisation values is further examined. Our study shows that the highest values of the cirrus lidar ratio correspond to higher values of cirrus depolarisation and warmer cirrus. The kind of information presented here can be rather useful in the cirrus parameterisations required as input to radiative transfer models and can be a complementary tool for satellite products that cannot provide cloud vertical structure. In addition, ground-based statistics of the cirrus properties could be useful in the validation and improvement of the corresponding derived products from satellite retrievals. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.
语种	英语
scopus关键词	cirrus; cloud classification; cloud microphysics; lidar; optical property; Raman spectroscopy; Finland; Kuopio; Pohjois-Savo; South Africa
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/141410
作者单位	Laboratory of Atmospheric Physics, Physics Department, Aristotle University of Thessaloniki, P.O. Box 54124, Thessaloniki, Greece; Department of Environmental Physics and Meteorology, Faculty of Physics, University of Athens, Athens, Greece; Finnish Meteorological Institute, P.O. Box 1627, Kuopio, 70211, Finland
推荐引用方式 GB/T 7714	Voudouri K.A.,Giannakaki E.,Komppula M.,et al. Variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes[J],2020,20(7).
APA	Voudouri K.A.,Giannakaki E.,Komppula M.,&Balis D..(2020).Variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes.Atmospheric Chemistry and Physics,20(7).
MLA	Voudouri K.A.,et al."Variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes".Atmospheric Chemistry and Physics 20.7(2020).