Abstract

A lidar system has been built to measure atmospheric-density fluctuations and the temperature in the upper stratosphere, the mesosphere, and the lower thermosphere, measurements that are important for an understanding of climate and weather phenomena. This lidar system, the Purple Crow Lidar, uses two transmitter beams to obtain atmospheric returns resulting from Rayleigh scattering and sodium-resonance fluorescence. The Rayleigh-scatter transmitter is a Nd:YAG laser that generates 600 mJ/pulse at the second-harmonic frequency, with a 20-Hz pulse-repetition rate. The sodium-resonance–fluorescence transmitter is a Nd:YAG-pumped ring dye laser with a sufficiently narrow bandwidth to measure the line shape of the sodium D 2 line. The receiver is a 2.65-m-diameter liquid-mercury mirror. A container holding the mercury is spun at 10 rpm to produce a parabolic surface of high quality and reflectivity. Test results are presented which demonstrate that the mirror behaves like a conventional glass mirror of the same size. With this mirror, the lidar system’s performance is within 10% of theoretical expectations. Furthermore, the liquid mirror has proved itself reliable over a wide range of environmental conditions. The use of such a large mirror presented several engineering challenges involving the passage of light through the system and detector linearity, both of which are critical for accurate retrieval of atmospheric temperatures. These issues and their associated uncertainties are documented in detail. It is shown that the Rayleigh-scatter lidar system can reliably and routinely measure atmospheric-density fluctuations and temperatures at high temporal and spatial resolutions.

© 1995 Optical Society of America

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References

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  1. L. Elterman, “A series of stratospheric temperature profiles obtained with the searchlight technique,” J. Geophys. Res. 58, 519–530 (1953).
    [CrossRef]
  2. G. Fiocco, L. D. Smullin, “Detection of scattering layers in the upper atmosphere (60–140 km) by optical radar,” Nature Phys. Sci. 199, 1275–1276 (1963).
    [CrossRef]
  3. C. S. Gardner, M. S. Miller, C. H. Liu, “Rayleigh lidar observations of gravity wave activity in the upper stratosphere at Urbana, Illinois,” J. Atmos. Sci. 46, 1838–1854 (1989).
    [CrossRef]
  4. R. Wilson, M. L. Chanin, A. Hauchecorne, “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 1. Case studies,” J. Geophys. Res. 96, 5153–5167 (1991); “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 2. Climatology,” J. Geophys. Res. 96, 5169–5183 (1991).
    [CrossRef]
  5. E. F. Borra, “Liquid mirrors: a review,” Can. J. Phys. (to be published).
  6. E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
    [CrossRef]
  7. P. Hickson, B. K. Gibson, D. Hogg, “Large astronomical liquid mirrors,” Publ. Astron. Soc. Pac. 105, 501 (1993); P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/LAVAL 2.7-meter liquid mirror telescope,” Astrophys. J. Lett. 436, L201–L203 (1994).
    [CrossRef]
  8. E. F. Borra, R. Content, L. Girard, “Optical shop tests of a f/1.2 2.5-meter diameter liquid mirror,” Astrophys. J. 418, 943–946 (1993).
    [CrossRef]
  9. P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/Laval 2.7-meter liquid mirror telescope,” Astrophys. J. (to be published).
  10. R. M. Measures, Lidar Remote Sensing: Fundamentals and Applications (Wiley, Ontario, 1984), Chap. 7.
  11. F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.
  12. M. L. Chanin, A. Hauchecorne, “Lidar studies of temperature and density using Rayleigh scattering,” in Handbook for MAP: Ground-Based Techniques, Vol. 13 of the Middle Atmosphere Program Series (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1984), paper 7.
  13. C. S. Gardner, D. C. Senft, T. J. Beatty, R. E. Bills, C. A. Hostetler, “Rayleigh and sodium lidar techniques for measuring middle atmosphere density, temperature, and wind perturbations and their spectra,” in World Ionosphere/Thermosphere Study Handbook, (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1989), Vol. 2, Chap. 6.
  14. A. E. Hedin, “Extension of the MSIS thermospheric model into the middle and lower atmosphere,” J. Geophys. Res. 96, 1159–1172 (1991).
    [CrossRef]
  15. I. I. Gringorten, A. J. Kantor, Y. Izumi, P. I. Tattelman, “Atmospheric temperatures, density, and pressure,” in Handbook of Geophysics and the Space Environment, Doc. ADA 167000 (National Technical Information Service, Springfield, Va., 1985), Section 15.1.

1993

P. Hickson, B. K. Gibson, D. Hogg, “Large astronomical liquid mirrors,” Publ. Astron. Soc. Pac. 105, 501 (1993); P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/LAVAL 2.7-meter liquid mirror telescope,” Astrophys. J. Lett. 436, L201–L203 (1994).
[CrossRef]

E. F. Borra, R. Content, L. Girard, “Optical shop tests of a f/1.2 2.5-meter diameter liquid mirror,” Astrophys. J. 418, 943–946 (1993).
[CrossRef]

1992

E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
[CrossRef]

1991

A. E. Hedin, “Extension of the MSIS thermospheric model into the middle and lower atmosphere,” J. Geophys. Res. 96, 1159–1172 (1991).
[CrossRef]

R. Wilson, M. L. Chanin, A. Hauchecorne, “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 1. Case studies,” J. Geophys. Res. 96, 5153–5167 (1991); “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 2. Climatology,” J. Geophys. Res. 96, 5169–5183 (1991).
[CrossRef]

1989

C. S. Gardner, M. S. Miller, C. H. Liu, “Rayleigh lidar observations of gravity wave activity in the upper stratosphere at Urbana, Illinois,” J. Atmos. Sci. 46, 1838–1854 (1989).
[CrossRef]

1963

G. Fiocco, L. D. Smullin, “Detection of scattering layers in the upper atmosphere (60–140 km) by optical radar,” Nature Phys. Sci. 199, 1275–1276 (1963).
[CrossRef]

1953

L. Elterman, “A series of stratospheric temperature profiles obtained with the searchlight technique,” J. Geophys. Res. 58, 519–530 (1953).
[CrossRef]

Abreu, L. W.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

Anderson, G. P.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

Beatty, T. J.

C. S. Gardner, D. C. Senft, T. J. Beatty, R. E. Bills, C. A. Hostetler, “Rayleigh and sodium lidar techniques for measuring middle atmosphere density, temperature, and wind perturbations and their spectra,” in World Ionosphere/Thermosphere Study Handbook, (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1989), Vol. 2, Chap. 6.

Bills, R. E.

C. S. Gardner, D. C. Senft, T. J. Beatty, R. E. Bills, C. A. Hostetler, “Rayleigh and sodium lidar techniques for measuring middle atmosphere density, temperature, and wind perturbations and their spectra,” in World Ionosphere/Thermosphere Study Handbook, (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1989), Vol. 2, Chap. 6.

Boily, E.

E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
[CrossRef]

Borra, E. F.

E. F. Borra, R. Content, L. Girard, “Optical shop tests of a f/1.2 2.5-meter diameter liquid mirror,” Astrophys. J. 418, 943–946 (1993).
[CrossRef]

E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
[CrossRef]

E. F. Borra, “Liquid mirrors: a review,” Can. J. Phys. (to be published).

P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/Laval 2.7-meter liquid mirror telescope,” Astrophys. J. (to be published).

Cabanac, R.

P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/Laval 2.7-meter liquid mirror telescope,” Astrophys. J. (to be published).

Chanin, M. L.

R. Wilson, M. L. Chanin, A. Hauchecorne, “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 1. Case studies,” J. Geophys. Res. 96, 5153–5167 (1991); “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 2. Climatology,” J. Geophys. Res. 96, 5169–5183 (1991).
[CrossRef]

M. L. Chanin, A. Hauchecorne, “Lidar studies of temperature and density using Rayleigh scattering,” in Handbook for MAP: Ground-Based Techniques, Vol. 13 of the Middle Atmosphere Program Series (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1984), paper 7.

Chetwynd, J. H.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

Clough, S. A.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

Content, R.

E. F. Borra, R. Content, L. Girard, “Optical shop tests of a f/1.2 2.5-meter diameter liquid mirror,” Astrophys. J. 418, 943–946 (1993).
[CrossRef]

E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
[CrossRef]

P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/Laval 2.7-meter liquid mirror telescope,” Astrophys. J. (to be published).

Elterman, L.

L. Elterman, “A series of stratospheric temperature profiles obtained with the searchlight technique,” J. Geophys. Res. 58, 519–530 (1953).
[CrossRef]

Fiocco, G.

G. Fiocco, L. D. Smullin, “Detection of scattering layers in the upper atmosphere (60–140 km) by optical radar,” Nature Phys. Sci. 199, 1275–1276 (1963).
[CrossRef]

Gallery, W. O.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

Gardner, C. S.

C. S. Gardner, M. S. Miller, C. H. Liu, “Rayleigh lidar observations of gravity wave activity in the upper stratosphere at Urbana, Illinois,” J. Atmos. Sci. 46, 1838–1854 (1989).
[CrossRef]

C. S. Gardner, D. C. Senft, T. J. Beatty, R. E. Bills, C. A. Hostetler, “Rayleigh and sodium lidar techniques for measuring middle atmosphere density, temperature, and wind perturbations and their spectra,” in World Ionosphere/Thermosphere Study Handbook, (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1989), Vol. 2, Chap. 6.

Gibson, B. K.

P. Hickson, B. K. Gibson, D. Hogg, “Large astronomical liquid mirrors,” Publ. Astron. Soc. Pac. 105, 501 (1993); P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/LAVAL 2.7-meter liquid mirror telescope,” Astrophys. J. Lett. 436, L201–L203 (1994).
[CrossRef]

P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/Laval 2.7-meter liquid mirror telescope,” Astrophys. J. (to be published).

Girard, L.

E. F. Borra, R. Content, L. Girard, “Optical shop tests of a f/1.2 2.5-meter diameter liquid mirror,” Astrophys. J. 418, 943–946 (1993).
[CrossRef]

E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
[CrossRef]

Gringorten, I. I.

I. I. Gringorten, A. J. Kantor, Y. Izumi, P. I. Tattelman, “Atmospheric temperatures, density, and pressure,” in Handbook of Geophysics and the Space Environment, Doc. ADA 167000 (National Technical Information Service, Springfield, Va., 1985), Section 15.1.

Hauchecorne, A.

R. Wilson, M. L. Chanin, A. Hauchecorne, “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 1. Case studies,” J. Geophys. Res. 96, 5153–5167 (1991); “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 2. Climatology,” J. Geophys. Res. 96, 5169–5183 (1991).
[CrossRef]

M. L. Chanin, A. Hauchecorne, “Lidar studies of temperature and density using Rayleigh scattering,” in Handbook for MAP: Ground-Based Techniques, Vol. 13 of the Middle Atmosphere Program Series (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1984), paper 7.

Hedin, A. E.

A. E. Hedin, “Extension of the MSIS thermospheric model into the middle and lower atmosphere,” J. Geophys. Res. 96, 1159–1172 (1991).
[CrossRef]

Hickson, P.

P. Hickson, B. K. Gibson, D. Hogg, “Large astronomical liquid mirrors,” Publ. Astron. Soc. Pac. 105, 501 (1993); P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/LAVAL 2.7-meter liquid mirror telescope,” Astrophys. J. Lett. 436, L201–L203 (1994).
[CrossRef]

P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/Laval 2.7-meter liquid mirror telescope,” Astrophys. J. (to be published).

Hogg, D.

P. Hickson, B. K. Gibson, D. Hogg, “Large astronomical liquid mirrors,” Publ. Astron. Soc. Pac. 105, 501 (1993); P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/LAVAL 2.7-meter liquid mirror telescope,” Astrophys. J. Lett. 436, L201–L203 (1994).
[CrossRef]

Hostetler, C. A.

C. S. Gardner, D. C. Senft, T. J. Beatty, R. E. Bills, C. A. Hostetler, “Rayleigh and sodium lidar techniques for measuring middle atmosphere density, temperature, and wind perturbations and their spectra,” in World Ionosphere/Thermosphere Study Handbook, (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1989), Vol. 2, Chap. 6.

Izumi, Y.

I. I. Gringorten, A. J. Kantor, Y. Izumi, P. I. Tattelman, “Atmospheric temperatures, density, and pressure,” in Handbook of Geophysics and the Space Environment, Doc. ADA 167000 (National Technical Information Service, Springfield, Va., 1985), Section 15.1.

Kantor, A. J.

I. I. Gringorten, A. J. Kantor, Y. Izumi, P. I. Tattelman, “Atmospheric temperatures, density, and pressure,” in Handbook of Geophysics and the Space Environment, Doc. ADA 167000 (National Technical Information Service, Springfield, Va., 1985), Section 15.1.

Kneizys, F. X.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

Liu, C. H.

C. S. Gardner, M. S. Miller, C. H. Liu, “Rayleigh lidar observations of gravity wave activity in the upper stratosphere at Urbana, Illinois,” J. Atmos. Sci. 46, 1838–1854 (1989).
[CrossRef]

Measures, R. M.

R. M. Measures, Lidar Remote Sensing: Fundamentals and Applications (Wiley, Ontario, 1984), Chap. 7.

Miller, M. S.

C. S. Gardner, M. S. Miller, C. H. Liu, “Rayleigh lidar observations of gravity wave activity in the upper stratosphere at Urbana, Illinois,” J. Atmos. Sci. 46, 1838–1854 (1989).
[CrossRef]

Selby, J. E. A.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

Senft, D. C.

C. S. Gardner, D. C. Senft, T. J. Beatty, R. E. Bills, C. A. Hostetler, “Rayleigh and sodium lidar techniques for measuring middle atmosphere density, temperature, and wind perturbations and their spectra,” in World Ionosphere/Thermosphere Study Handbook, (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1989), Vol. 2, Chap. 6.

Shettle, E. P.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

Smullin, L. D.

G. Fiocco, L. D. Smullin, “Detection of scattering layers in the upper atmosphere (60–140 km) by optical radar,” Nature Phys. Sci. 199, 1275–1276 (1963).
[CrossRef]

Szapiel, S.

E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
[CrossRef]

Tattelman, P. I.

I. I. Gringorten, A. J. Kantor, Y. Izumi, P. I. Tattelman, “Atmospheric temperatures, density, and pressure,” in Handbook of Geophysics and the Space Environment, Doc. ADA 167000 (National Technical Information Service, Springfield, Va., 1985), Section 15.1.

Tremblay, L. M.

E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
[CrossRef]

Walker, G. A. H.

P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/Laval 2.7-meter liquid mirror telescope,” Astrophys. J. (to be published).

Wilson, R.

R. Wilson, M. L. Chanin, A. Hauchecorne, “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 1. Case studies,” J. Geophys. Res. 96, 5153–5167 (1991); “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 2. Climatology,” J. Geophys. Res. 96, 5169–5183 (1991).
[CrossRef]

Astrophys. J.

E. F. Borra, R. Content, L. Girard, “Optical shop tests of a f/1.2 2.5-meter diameter liquid mirror,” Astrophys. J. 418, 943–946 (1993).
[CrossRef]

E. F. Borra, R. Content, L. Girard, S. Szapiel, L. M. Tremblay, E. Boily, “Liquid mirrors: optical shop tests and contributions to the technology,” Astrophys. J. 393, 829–847 (1992).
[CrossRef]

J. Atmos. Sci.

C. S. Gardner, M. S. Miller, C. H. Liu, “Rayleigh lidar observations of gravity wave activity in the upper stratosphere at Urbana, Illinois,” J. Atmos. Sci. 46, 1838–1854 (1989).
[CrossRef]

J. Geophys. Res.

R. Wilson, M. L. Chanin, A. Hauchecorne, “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 1. Case studies,” J. Geophys. Res. 96, 5153–5167 (1991); “Gravity waves in the middle atmosphere observed by Rayleigh lidar, 2. Climatology,” J. Geophys. Res. 96, 5169–5183 (1991).
[CrossRef]

L. Elterman, “A series of stratospheric temperature profiles obtained with the searchlight technique,” J. Geophys. Res. 58, 519–530 (1953).
[CrossRef]

A. E. Hedin, “Extension of the MSIS thermospheric model into the middle and lower atmosphere,” J. Geophys. Res. 96, 1159–1172 (1991).
[CrossRef]

Nature Phys. Sci.

G. Fiocco, L. D. Smullin, “Detection of scattering layers in the upper atmosphere (60–140 km) by optical radar,” Nature Phys. Sci. 199, 1275–1276 (1963).
[CrossRef]

Publ. Astron. Soc. Pac.

P. Hickson, B. K. Gibson, D. Hogg, “Large astronomical liquid mirrors,” Publ. Astron. Soc. Pac. 105, 501 (1993); P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/LAVAL 2.7-meter liquid mirror telescope,” Astrophys. J. Lett. 436, L201–L203 (1994).
[CrossRef]

Other

I. I. Gringorten, A. J. Kantor, Y. Izumi, P. I. Tattelman, “Atmospheric temperatures, density, and pressure,” in Handbook of Geophysics and the Space Environment, Doc. ADA 167000 (National Technical Information Service, Springfield, Va., 1985), Section 15.1.

E. F. Borra, “Liquid mirrors: a review,” Can. J. Phys. (to be published).

P. Hickson, E. F. Borra, R. Cabanac, R. Content, B. K. Gibson, G. A. H. Walker, “UBC/Laval 2.7-meter liquid mirror telescope,” Astrophys. J. (to be published).

R. M. Measures, Lidar Remote Sensing: Fundamentals and Applications (Wiley, Ontario, 1984), Chap. 7.

F. X. Kneizys, E. P. Shettle, L. W. Abreu, J. H. Chetwynd, G. P. Anderson, W. O. Gallery, J. E. A. Selby, S. A. Clough, “Users guide to lowtran 7,” AFGL Env. Res. Pap. 1010 (Air Force Geophysics Laboratory, Hanscom Air Force Base, Mass., 1988), Chap. 1.

M. L. Chanin, A. Hauchecorne, “Lidar studies of temperature and density using Rayleigh scattering,” in Handbook for MAP: Ground-Based Techniques, Vol. 13 of the Middle Atmosphere Program Series (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1984), paper 7.

C. S. Gardner, D. C. Senft, T. J. Beatty, R. E. Bills, C. A. Hostetler, “Rayleigh and sodium lidar techniques for measuring middle atmosphere density, temperature, and wind perturbations and their spectra,” in World Ionosphere/Thermosphere Study Handbook, (Scientific Committee on Solar Terrestrial Physics, International Council of Scientific Unions, Urbana, Ill., 1989), Vol. 2, Chap. 6.

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Figures (11)

Fig. 1
Fig. 1

Schematic diagram of the Purple Crow Lidar system. The laser table is 1.2 m × 3 m. The liquid-mirror telescope is 2.65 m in diameter and has a focal length of 5.175 m.

Fig. 2
Fig. 2

Basic components of a liquid mirror.

Fig. 3
Fig. 3

Closing procedure for the mercury surface of the 2.65-m liquid mirror (read the sequence from the top-left photograph to the lower-right photograph). In the top-left photograph, the operator has just cleaned the mercury in the center of the container by skimming the surface with a weighted piece of tubing and then vacuuming off the dirty mercury, which is filtered and reused. The operator begins to spin the container sufficiently fast to move the mercury out to the edge of the container (top-right and lower-left photographs). The middle-bottom photograph shows a Mylar flag as it is used to drag the mercury toward the center of the container. After a few minutes, when the surface is closed, the flag is carefully removed and cleaned.

Fig. 4
Fig. 4

Total Rayleigh-scatter photocounts between 30 and 70 km measured during the stabilization of the liquid mirror. This test shows that the liquid mirror’s focal length is sufficiently stable for lidar observations approximately 130 min after the mirror surface has been closed.

Fig. 5
Fig. 5

Measured gain variation resulting from dynode-gating the photomultiplier with a constant, stable light source. The gain of the photomultiplier decreases 8% over the height range of interest for the Rayleigh-scatter measurement in this mode of operation. The solid curve represents the gain-variation measurement, and the dotted line indicates unity gain.

Fig. 6
Fig. 6

Correction curves from five nights and seven LED calibration runs conducted during the past year through the use of the ratio of counts with and without a sufficient neutral-density filter to keep the count rates linear. This correction introduces an uncertainty in the accuracy of the measurements at the lower heights that is proportional to the vertical bars shown at the ±1σ level of variation.

Fig. 7
Fig. 7

Comparison of measured and calculated photocounts: The solid curve represents 364 min of Rayleigh-scatter returns at a height resolution of 24 m obtained on 31 August 1994, with the background removed as described in Section 3. The measurements have been smoothed with a 15-point running average. The circles are the anticipated returns calculated from the lidar equation (2) with the system parameters listed in Table 1 and the appropriate MSIS-90 model-atmosphere density profile. The agreement between the measurement and the calculation values are within approximately 10% and suggest that the liquid-mirror receiver’s performance is equivalent to that of a conventional glass mirror with the same reflectivity.

Fig. 8
Fig. 8

Rayleigh-scatter temperature measurements for the same measurement period described for Fig. 7. The measurements were obtained at a 48-m height resolution then smoothed with a digital filter with a 1-km cutoff. The dotted curve is the MSIS-90 model-atmosphere temperature profile for the geophysical conditions appropriate for that night. The shading is the ±1σ statistical error of the temperature. The temperature-profile integration commenced at a signal-to-noise ratio of 2 at a height of 103 km.

Fig. 9
Fig. 9

Temperature variations at a height resolution of 48 m at three selected altitudes, (a) 72 km, (b) 54 km, and (c) 40 km, at 10-min intervals over the same period described for Fig. 8. The 10-min profiles have been processed similarly to the average profile shown in Fig. 8. The ordinate value of 0 h is 0332 UT (midnight Eastern Daylight Time is 0400 UT). Temperature variations of the order of 10 K, significantly above the measurement error, are apparent.

Fig. 10
Fig. 10

Uncertainty resulting from photomultiplier corrections (solid curve) compared with the statistical error (unsmoothed curve) for a 1-min interval on 31 August 1994. The correction uncertainty is due to variations at high count rates for the photomultiplier-correction curve shown in Fig. 6. The correction uncertainty is independent of the integration time, whereas the statistical error scales as the square root of the photocounts.

Fig. 11
Fig. 11

Estimate of the temperature error through a comparison of two temperature-measurement intervals: (a) Rayleigh-scatter signal at 35 km altitude on 30 September 1994 from 2035–0034 solar local time (0200–0600 UT) showing a period of varying cloud cover followed by clear skies. (b) Stratospheric temperature measurements averaged over the clear period (solid curve) and the cloudy period (dotted curve). The difference between the two profiles below 35 km, where the correction of the photomultiplier counts is the largest, is consistent with the underestimation of the count rate during the cloudy period because of rapid atmospheric-transmission variations over the 1-min time interval in which the profile was acquired. The clear-sky measurements are in close agreement with the predictions of the MSIS-90 model.

Tables (2)

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Table 1 PCL Rayleigh-Scatter System Parameters

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Table 2 Uniformity Test Results for the Liquid Mirror

Equations (3)

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L = g 2 ω 2 ,
N ( z ) = β [ σ R ρ ( z ) ] z 2 ,
σ top ( z ) = ( T top - T model top ) ρ ( z top ) ρ ( z ) ,

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