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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:10 |
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Conference: Bucharest University Faculty of Physics 2005 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Lidar techniques for lower atmosphere
Authors:
G.J. Ciuciu
Affiliation:
National Institute of R&D for Optoelectronics
E-mail
jeni@inoe.inoe.ro
Keywords:
remote sensing, lidar
Abstract:
Lidar (Light Detection and Ranging) technique is an active remote sensing method. The main principals are: emission of short laser pulses (ns or fess duration) to the atmosphere under study and reception of radiation scattered in backward direction that provide backscattering signal as a function of distance of sensing. This backscattering signal is generated by air density fluctuation and small aerosol particles presented in atmosphere. A lidar system can evidence and characterize gaseous pollutants and aerosols which cause o large class of phenomena affecting the climate.
LiSA system - a dedicated backscattering lidar for troposphere aerosols detection studies -contains three main units: transmitting unit, receiving unit, data registration and processing unit. The transmitting unit is a pulsed, Q-switched Nd:YAG laser (with power supply, cooling system, remote control), which can work separately or simultaneous on two wavelengths (1064 nm and 532 nm – fundamental and second harmonic for Nd:YAG laser). The backscattering radiation is received by a telescope in relation with photomultipliers. The emission and receiving parts are synchronised and the signal is saved in a PC.
By comparison with other similar instruments, Lidar systems have a high monochromaticity and a controlled radiation polarisation,a high spectral resolution and energy density per unit of frequency spectrum. This technique is used to estimate the pollution level in atmosphere, the distance for planetary boundary layer and clouds base.
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