20 October 1999 TURTLE: turbopause underside rocket temperature lidar experiment
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The night-time temperature in the altitude region from 90 to 120 km is known to be characterized by a steep gradient caused by heating due to ultraviolet absorption of sunlight in the middle thermosphere during the day, yet measurements of this gradient are scarce. Remote optical sensing methods fail in this region because the few nightglow emissions above 100 km are contaminated by photochemical reaction energy. We address this measurement by considering the scattered return signal from a laser emitting horizontally from a rocket as it traverses the region. Two analyses are presented. The ideal method consists of measurement of the Raman rotational spectrum of the combined N2 and O2 back-scattered signals by means of interference filter spatial spectral scanning. A quantitative estimate of such a measurement shows that this method, while only marginally practical at the moment, holds significant promise. The second method consists of measuring the back-scattered Rayleigh signal, which is a thousand times brighter, and deducing the temperature from the density scale height. This measurement is shown by quantitative precision estimates to be practical using today's technology. Proposed optical configurations for both methods are presented, and the limitations of both are explored.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Rudolph H. Wiens, Paul J. Thomas, "TURTLE: turbopause underside rocket temperature lidar experiment", Proc. SPIE 3756, Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research III, (20 October 1999); doi: 10.1117/12.366385; https://doi.org/10.1117/12.366385

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