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Optical Engineering

Tropospheric O3 measurement by simultaneous differential absorption lidar and null profiling and comparison with sonde measurement
Author(s): Tetsuo Fukuchi; Takashi Fujii; Nianwen Cao; Koshichi Nemoto; Nobuo Takeuchi
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Paper Abstract

A differential absorption lidar (DIAL) system consisting of two identical tunable laser systems and a single optical receiver is applied to measurement of O3 concentration profiles in the lower troposphere. Each laser is capable of emitting two wavelengths on alternate pulses, so the system is capable of simultaneous measurement of two species in the same wavelength region. We set the two lasers to emit at identical wavelength pairs consisting of on wavelength 285.0 nm and off wavelength 290.1 nm for simultaneous measurement of two null profiles, one at each wavelength, and two DIAL profiles, or O3 concentration profiles. Null profiles are useful in estimating instrumental error and checking the vertical range interval in which the DIAL profiles are accurate. Null and DIAL profiles are obtained for vertical range 1000 to 4000 m using neutral density filters of different transmissions to prevent the strong return signals from close range from saturating the photodetector. The obtained O3 concentration profiles agree with simultaneous O3 sonde measurements. An evaluation of the measurement error shows that the average O3 measurement error for vertical range 1000 to 4000 m was 3.4 ppb, or 8% relative to the average O3 concentration of 42.3 ppb, most of which is due to statistical error. The error due to differential Mie attenuation and differential backscatter gradient was found to be 0.5 ppb.

Paper Details

Date Published: 1 September 2001
PDF: 6 pages
Opt. Eng. 40(9) doi: 10.1117/1.1396839
Published in: Optical Engineering Volume 40, Issue 9
Show Author Affiliations
Tetsuo Fukuchi, Central Research Institute of Electric Power Industry (Japan)
Takashi Fujii, Central Research Institute of Electric Power Industry (Japan)
Nianwen Cao, Central Research Institute of Electric Power Industry (Japan)
Koshichi Nemoto, Central Research Institute of Electric Power Industry (Japan)
Nobuo Takeuchi, Chiba Univ. (Japan)


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