Ceilometer inversion method using water-vapor correction from co-located microwave radiometer for aerosol retrievals
International audience Ceilometers are widely spread instruments mainly used for cloud base height determination. However, recent models are more sensitive to aerosols; hence, nowadays there is an increasing interest in these instruments to retrieve aerosol optical and microphysical properties.The h...
Published in: | Atmospheric Research |
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Main Authors: | , , , , , , , |
Other Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2021
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Subjects: | |
Online Access: | https://hal.science/hal-02865809 https://hal.science/hal-02865809v2/document https://hal.science/hal-02865809v2/file/DOTA20096_postprint.pdf https://doi.org/10.1016/j.atmosres.2020.105379 |
Summary: | International audience Ceilometers are widely spread instruments mainly used for cloud base height determination. However, recent models are more sensitive to aerosols; hence, nowadays there is an increasing interest in these instruments to retrieve aerosol optical and microphysical properties.The high number of them distributed around the globe compared to the robust lidar systems and the fact that ceilometers work under unattended conditions are the main reasons behind this interest. In this paper a new methodology is proposed to retrieve aerosol vertical extinction and backscatter profiles from a Vaisala ceilometer CL51. This methodology is based in two parts: first, a signal pre-processing with a suppression of the dark current and background noises, and a correction of the water vapor absorption using near-real time temperature and absolute humidity (AH) profiles from a co-located Microwave radiometer (MWR). Then an iterative Klett-based algorithm that uses AERONET (AErosol RObotic NETwork) AOD (Aerosol Optical Depth) as an input to retrieve the extinction and backscatter profiles. The error analysis of the aerosol retrievals has been performed between MWR measurements and modelled radiosondes from HYSPLIT. The absolute errors found in temperature and AH are leading to errors in the pre-processed RCS signals up to 9%, and then in particle backscatter and particle extinction coefficients up to 2:2% and 25%, respectively. Les ceilomètres sont des instruments très répandus, principalement utilisés pour déterminer la hauteur de la base des nuages. Cependant, des modèles récents sont plus sensibles aux aérosols c'est pourquoi, de nos jours, on s'intéresse de plus en plus à ces instruments pour mesurer des données optiques des aérosols et leurs propriétés microphysiques. Le nombre élevé de ces derniers, répartis dans le monde entier, par rapport aux systèmes lidar robustes et le fait que les plafonds fonctionnent dans des conditions non surveillées sont les principales raisons de cet intérêt. Dans ce ... |
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