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Proceedings Paper

Development of Rayleigh Doppler lidar system for measuring middle atmosphere winds
Author(s): Raghunath Karnam; Amit Kumar Patra; Narayana Rao Daggumati
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Paper Abstract

Measurement of middle and upper atmosphere winds is needed to understand the structure and dynamics in these regions. Rayleigh Doppler lidars can give continuous information of winds routinely. Details of the ongoing development of Rayleigh Doppler lidar at National Atmospheric Research Laboratory, India with performance simulations and system specifications are described. The system with 5.3 W-m2 average power aperture product employs Double Edge technique with etalons, and is expected to give ~5 m/s wind accuracies with one hour time integration and 1 km range resolution at a height of 60km. The presentation is about the design and development of Incoherent Doppler lidar to obtain wind information in the height regions of 30-65 km. The lidar system measures winds and temperatures from the spectral shift due to the motions of atmospheric molecules with background winds and the broadening of the signal by the atmospheric molecules, energised by the incident laser pulse. The lidar receives the signals in at least three directions. The important specifications which has a bearing on the wind measurements are line width and stability of the laser source. To track the instabilities in the laser source and etalons, a pulse-to-pulse calibration technique is planned. The system employing Edge technique measures the Doppler shift of the backscattered echo, by inter-comparing the signal detected through each of the two narrow band-passes of a single dual Fabry-Perot interferometer tuned to either side of the emitted line. In higher altitudes, the wind error is primarily due to the statistical standard error and spectral broadening (Cramer-Rao Lower Bound) and is independent of the wind velocity and is only height dependent. The paper brings out the scientific objectives, configuration, simulations, error sources and technical challenges involved in the development of Rayleigh Doppler lidar. The paper analyses and describes various types of techniques that can be adopted viz. Edge technique and Fringe Imaging technique.

Paper Details

Date Published:
PDF: 8 pages
Proc. SPIE 6409, Lidar Remote Sensing for Environmental Monitoring VII, 64090R; doi: 10.1117/12.693544
Show Author Affiliations
Raghunath Karnam, National Atmospheric Research Lab., Dept. of Space (India)
Amit Kumar Patra, National Atmospheric Research Lab., Dept. of Space (India)
Narayana Rao Daggumati, National Atmospheric Research Lab., Dept. of Space (India)

Published in SPIE Proceedings Vol. 6409:
Lidar Remote Sensing for Environmental Monitoring VII
Upendra N. Singh; Toshikazu Itabe; D. Narayana Rao, Editor(s)

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