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Proceedings Paper

Infrared lidar windshear detection for commercial aircraft and the edge technique: a new method for atmospheric wind measurement
Author(s): Russell Targ; Roland L. Bowles; C. Laurence Korg; Bruce M. Gentry; Dominique Jacques Souilhac
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Paper Abstract

National attention has focused on the critical problem of detecting and avoiding windshear since the crash on August 2, 1985, of a Lockheed L-1011 at Dallas/Fort Worth International Airport. As part of The NASA/FAA National Integrated Windshear Program, we have defined a measurable windshear hazard index that can be remotely sensed from an aircraft, to give the pilot information about the wind conditions he will experience at some later time if he continues along the present flight path. Our technology analysis and end-to-end performance simulation, which measured signal-to-noise ratios and resulting wind velocity errors for competing coherent lidar systems, showed that a Ho:YAG lidar at a wavelength of 2.1 μm and a CO2 lidar at 10.6 m can give the pilot information about the line-of-sight component of a windshear threat in a region extending from his present position to 2 to 4 km in front of the aircraft. This constitutes a warning time of 20 to 40 s, even under conditions of moderately heavy precipitation. Using these results, a Coherent Lidar Airborne Shear Sensor (CLASS), using a Q-switched CO2 laser at 10.6 μm, is being designed and developed for flight evaluation in early 1992. The edge technique is a powerful new method for the measurement of small frequency shifts which allows high accuracy measurement of atmospheric winds (0.2 to 1 m/sec) with high vertical resolution (10 meters) using currently available technology.

Paper Details

Date Published: 1 May 1991
PDF: 14 pages
Proc. SPIE 1521, Image Understanding for Aerospace Applications, (1 May 1991); doi: 10.1117/12.46057
Show Author Affiliations
Russell Targ, Lockheed Palo Alto Research Lab. (United States)
Roland L. Bowles, NASA/Langley Research Ctr. (United States)
C. Laurence Korg, NASA/Goddard Space Flight Ctr. (United States)
Bruce M. Gentry, NASA/Goddard Space Flight Ctr. (United States)
Dominique Jacques Souilhac, ENSEM Antenne de Nevers (France)

Published in SPIE Proceedings Vol. 1521:
Image Understanding for Aerospace Applications
Hatem N. Nasr, Editor(s)

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