ICLAS: International Coordination-group on Laser Atmospheric Studies
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LIDAR RESEARCHER: Dr. Takashi Fujii

RESEARCH ASSOCIATES:
Dr. Tetsuo Fukuchi, Dr. Nianwen Cao, Mr. Takuya Nayuki, Dr. Naohiko Goto, Prof. Dr. Koshichi Nemoto

MAILING ADDRESS:
Electrical Physics Department
Central Research Institute of Electric Power Industry (CRIEPI)
2-11-1, Iwado Kita, Komae-shi, Tokyo 201-8511 Japan

TELEPHONE NUMBER:
+81-(0)3-3480-2111

FAX NUMBER:
+81-(0)3-3480-3401

E-MAIL ADDRESS:
fujii@criepi.denken.or.jp

WEB SITE: http://
Non

DATE:
November 8, 2001

LIDAR LOCATION (CITY, COUNTRY, LAT., LONG.):
Komae City, Tokyo, Japan, 35 deg 38 min N, 139 deg 35 min E (about 20 km west of downtown Tokyo)

SITE ELEVATION:
20 m

PARAMETER(S) OR CONSTITUENT(S) MEASURED:
Now: SO2, NO2, O3, Hg (by DIAL), Aerosol extinction and backscatter coefficients (by Mie lidar)
Near future: Water vapor, O3, (Temperature?) (by Raman lidar)

RESEARCH OBJECTIVES AND SPONSOR:
Research objectives: To investigate generation, transportation and reaction mechanisms of air pollutants
Sponsor: Electric power industries in Japan

MEASUREMENT TECHNIQUE:
DIAL, Mie lidar, Raman lidar

MEASUREMENT RANGE:
- SO2: 1000-4000 m
- NO2: 1000-2000 m (day time), 1000-3000 m (night time)
- O3: 1000-4000 m
- Hg: 400-700 m (under construction)
SO2, NO2 and O3 measurements in shorter range (>400m) may be possible.

VERTICAL RESOLUTION:
- SO2: <0.3 ppm?m (Typical range resolution: 150-300 m)
- NO2: <1 ppm?m (Typical range resolution: 150-300 m)
- O3: <0.5 ppm?m (Typical range resolution: 150-300 m)

FREQ. OF MEASUREMENT (TYPICALLY):
1-2 weeks in a month

MEASUREMENT TIMES (TYPICALLY):
5-10 minute integration for 1 profile, continuous acquisition of profiles for up to 24 hours

LASER TYPE AND WAVELENGTH (s):
Nd: YAG laser (HOYA Continuum Powerlite 8010) pumped dye lasers (HOYA Continuum ND6000)
Wavelength: 250-900 nm

LASER ENERGY/PULSE:
250nm (for Hg): 2 mJ
285-290nm (for O3): 15-25 mJ
300nm (for SO2): 30 mJ
450nm (for NO2): 20 mJ
532nm (for aerosol): 50 mJ

PULSE REPETITION RATE:
10 Hz

RECEIVER SIZE AND CONFIGURATION:
Primary-mirror diameter: 500 mm
Newtonian telescope

DETECTORS USED:
Photomultiplier tube (Hamamatsu R3896)

SIGNAL PROCESSING:
Digitized PMT signals are averaged over an integration time for each wavelength and treated as return signals with 7.5m range resolution. Vertical profiles of the target substances' concentrations and aerosol extinction and backscatter coefficients are obtained by using the following manner: (1) subtract the background level obtained from the return signal before the firing of the laser, (2) average all signals over an appropriate number of time bins, for example, 40 bins for a range resolution of 300 m, and (3) calculate the substances' concentration profiles by use of DIAL equation, and aerosol extinction and backscatter coefficients by the Klett or Fernald method.

ANALOG-T0-DIGITAL CONVERTER:
Transient digitizer (GaGe CS1012), 12 bits, 20 MHz

COMPUTER:
Personal computer, Windows NT

PLATFORM (if applicable):
not applicable

PUBLICATIONS (5 recent and/or significant):
1. T. Fujii, T. Fukuchi, N. Cao, K. Nemoto, and N. Takeuchi, "Trace atmospheric SO2 measurement by multiwavelength curvefitting and wavelength optimized dual differential absorption lidar," to be published in Appl. Opt. 43, No. 3, January (2002).
2. N. Cao, T. Fujii, T. Fukuchi, N. Goto, K. Nemoto, and N. Takeuchi, "Estimation of DIAL measurement error for NO2 profiling in the lower troposphere," to be published in Opt. Eng. 40, No. 12, December (2001).
3. T. Fukuchi, T. Fujii, N. Cao, K. Nemoto, and N. Takeuchi, "Tropospheric O3 measurement by simultaneous differential absorption lidar and null profiling and comparison with sonde measurement," Opt. Eng. 40, 1944-1949 (2001).
4. T. Fujii, T. Fukuchi, N. Goto, K. Nemoto, and N. Takeuchi, "Dual differential absorption lidar for the measurement of atmospheric SO2 of the order of parts in 109," Appl. Opt. 40, 949-956 (2001).
5. T. Fukuchi, T. Fujii, N. Goto, K. Nemoto, and N. Takeuchi, "Evaluation of differential absorption lidar (DIAL) measurement error by simultaneous DIAL and null profiling," Opt. Eng. 40, 392-397 (2001).

COMMENTS:
Our transmitter is composed of two dye lasers each of which can emit two wavelengths on alternate pulses, and the receiver has two detector channels. Therefore, the system can simultaneously measure two pollutants, e.g. O3 and NO2. The system is also capable of multiwavelength (3 or 4 wavelengths) measurement of one pollutant, e.g. trace SO2, when higher sensitivity than conventional 2 wavelengths DIAL is needed. Raman lidar is under preparation, and will be ready in spring 2002.

 
 

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