Lidar can also be used for cirrus observations

Cirrus clouds are high, cold clouds composed of asymmetric ice particles. Thin cirrus clouds cause a net heating of the Earth because they allow visible sunlight to pass almost unhindered while at the same time absorbing and reradiating infrared radiation from the surface below. Their properties vary depending on geographic location and season.

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In our study, a multiwavelength lidar system was used to retrieve cirrus cloud properties in three different locations, from South Africa to India and Finland. Lidar ratio values also exhibit a pattern, showing higher values moving toward the poles, with higher mean values observed over the subarctic site. Our results reveal that the highest values of the cirrus lidar ratio correspond to higher values of cirrus depolarisation and warmer cirrus.

The kind of information presented in this study 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.

More information:

Researcher Eleni Giannakaki, 0504088653, eleni.giannakaki@fmi.fi

Kalliopi Artemis Voudouri, Elina Giannakaki, Mika Komppula, and Dimitris Balis. Variability in cirrus cloud properties using a PollyXT Raman lidar over high and tropical latitudes. Atmos. Chem. Phys., 20, 4427–4444, 2020. https://acp.copernicus.org/articles/20/4427/2020/

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