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Restitution des propriétés microphysiques et radiatives des nuages froids et mixtes à partir des données du système RALI (RAdar-LIdar)

Abstract : Clouds play an important role in atmospheric processes and climate control. However their parametric representation in numerical models for weather forecast and climate is still simplistic and not yet validated. The desire to understand the radiative impact of clouds has driven the definition of two space missions using a radar-lidar combination (CLOUDSAT/CALIPSO and EarthCARE). The RALI system (synergetic Cloud Radar- Lidar system) is an airborne demonstrator for both of the above-mentioned instruments that help at once the development of the associated algorithms and the calibration of the space mission products. Thus, RALI aims at the development and exploitation of a synergetic airborne or ground-based radar-lidar combination in order to document vertical profiles of microphysical, dynamical and radiative properties of non-precipitating iced clouds. This thesis comes within this scope. At first, an inverse model relating remote sensing variables to the cloud parameters was built. This model enables to free from the shape of the particle size distribution and is used as the basic principle of the radar-lidar synergetic algorithm. This algorithm was also developed to take into account the natural vertical variability of cloud particles concentration. Simulation tests were performed in order to determine robustness, precision and the optimal conditions of application. Results from field experiment (CLARE 98, CARL 99, CLARE 2000) were compared with in-situ microphysical measurements and have demonstrated the capacity of the algorithm to retrieve effective radii of clouds particles, ice water content and optical depth of sounded clouds. The algorithm is also able to retrieve the water contents for the mixed-phase layers and this capability was tested on an altocumulus case of CLARE 2000.
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Contributor : Claire Tinel <>
Submitted on : Tuesday, January 20, 2004 - 3:49:49 PM
Last modification on : Friday, March 27, 2020 - 3:00:50 AM
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  • HAL Id : tel-00004241, version 1



Claire Tinel. Restitution des propriétés microphysiques et radiatives des nuages froids et mixtes à partir des données du système RALI (RAdar-LIdar). Océan, Atmosphère. Université Paris-Diderot - Paris VII, 2002. Français. ⟨tel-00004241⟩



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