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UP: Fachverband Umweltphysik
UP 5: Poster Session
UP 5.3: Poster
Mittwoch, 18. März 2020, 14:00–16:00, P2/4OG
Identification and Characterization of Cirrus Clouds at Higher Latitudes from Lidar Data — •Jennifer Hartisch1, Jörg Gumbel2, and Christian v. Savigny3 — 1Greifswald University, Physics Institute, Germany — 2Stockholm University, MISU, Sweden — 3Greifswald University, Physics Institute, Germany
Cirrus clouds are thin ice clouds that occur in the cold upper troposphere. Clouds have both a warming and a cooling effect on the Earth's system. Which of these processes dominates depends on surrounding conditions and properties of the cloud, especially on their optical thickness. The cirrus' net warming effect is strongest in the tropics, where they occur at very high and cold altitudes. The effect of cirrus clouds at higher latitudes, where they occur at 8-10 km altitude is much less known. From 1987 to 2017 observations of cirrus clouds in Northern Sweden with a Rayleigh/Mie/Raman lidar at Esrange Space Center have been performed. To identify and characterize cirrus clouds in these lidar data, appropriate analysis methods are needed that start out from the particle backscattering at the primary lidar wavelength of 532 nm. A particular challenge is to distinguish the cirrus scattering from molecular Rayleigh scattering by the background atmosphere. This is achieved by invoking measurements of molecular Raman scattering. This research describes analysis algorithms that let us derive important cirrus parameters like occurrence, height, optical thickness, as well as extinction and scattering coefficients. A central goal is to establish a climatology of the clouds' occurrence and optical properties as a function of meteorological conditions at these high latitudes.