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Proceedings Paper

Use of a rapid-scanning backscatter LIDAR to validate dispersion models
Author(s): Michael Bennett
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Paper Abstract

We review the history and capabilities of UMIST's Rapid- scanning Lidar (RASCAL). This is a backscatter Lidar designed to study aerosol dispersion from industrial plant. The system is fully computer-controlled and is based around a frequency- doubled Nd-YAG laser having a pulse repetition rate of 30 Hz. The signal is measured with a 10-bit, 60 MHz digitizer. Overall, a plume cross-section can be obtained in < 2 s and repeated every approximately 4 s. Such scanning can continue for several hours. Range resolution is typically 5 m with sensitivity down two a few (mu) g m-3 of aerosol. Over 10 years we have developed software to analyze the returns to estimate plume height, spread and intermittency; wind speed at plume height; and mixing layer depth. The backscatter from combustion plant plumes appears to be well enough conserved to allow point measurements within the plume to be interpreted as concentration/flux ratios, (c/Q) for comparison with dispersion models. This technique has recently been successfully tested using a chemical tracer. A substantial dataset acquired with the system has been used to test the predictions of various regulatory models. We present recent comparisons of modelled and measured c/Q at a small power station: the ensemble values show impressive agreement.

Paper Details

Date Published: 9 April 2001
PDF: 9 pages
Proc. SPIE 4397, 11th International School on Quantum Electronics: Laser Physics and Applications, (9 April 2001); doi: 10.1117/12.425181
Show Author Affiliations
Michael Bennett, UMIST (United Kingdom)

Published in SPIE Proceedings Vol. 4397:
11th International School on Quantum Electronics: Laser Physics and Applications
Peter A. Atanasov; Stefka Cartaleva, Editor(s)

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