Author: Raymond E Zirkle (Jr)

Publisher:

Published: 1966

Total Pages: 135

ISBN-13:

Two general ways in which laser optical radar (optar) might be useful for clear air turbulence detection were examined. The first method involves spectral analysis of doppler-shifted light, backscattered by moving particles, to provide measures of average and gust spectrum velocity components. The second method involves the mapping of particle formations arrayed in the atmosphere by correlates of rough flying conditions such as wind shear, the jet stream, mountain waves, etc. Calculations show that the particulate matter of the troposphere which dominates optical backscatter is dynamically suitable for the mapping of wind motions consistent with anticipated requirements of CAT detection. Experiments by other groups have shown that laser doppler methods can measure particle velocities in the laboratory. Experimental extensions of these techniques will be needed to apply the concept to aircraft. An experimental program with pulsed ruby laser optars was conducted. Particle arrays were detected in both laboratory and field environments, but no evidence was obtained indicating a correlation with turbulent conditions. Laboratory turbulence-generated refractive index changes were much higher than those encountered in the atmosphere. Field tests at Rollinsville, Colorado were inconclusive due to poor weather conditions. Many cloud returns were obtained, but they were not related to mountain waves or turbulence. Airborne optars should be used in further work of this type to provide mobility and to allow direct correlation between signals received and turbulence encountered. (Author).