Abstract

The generation of ruby lidar depolarization from multiple scattering in marine stratus clouds has been examined systematically from a field site on the southern California coast. Investigated were the effects on the linear depolarization ratio δ of lidar receiver field of view (FOV), elevation angle, and laser alignment error. An approximately linear increase in maximum δ values was observed with increasing receiver FOV, and the importance of accurate transmitter/receiver alignment has been demonstrated. An elevation angle dependence to the δ values was observed as a consequence of the vertical inhomogeneity of water cloud content above cloud base. Time histories of the depolarization characteristics of dissipating stratus clouds revealed significant variability in δ values due to cloud composition variations. Employing a 1-mrad transmiter FOV, maximum δ values of 0.21 and 0.33 were observed with 1- and 3-mrad receiver FOVs, respectively.

© 1986 Optical Society of America

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References

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  1. D. Deirmendjian, Electromagnetic Scattering on Spherical Polydispersions (American Elsevier, New York, 1969).
  2. R. M. Schotland, K. Sassen, R. Stone, “Observations by Lidar of Linear Depolarization Ratios for Hydrometeors,” J. Appl. Meteorol. 10, 1011 (1971).
    [CrossRef]
  3. K. N. Liou, H. Lahore, “Laser Sensing of Cloud Composition: A Backscattered Depolarization Technique,” J. Appl. Meteorol. 13, 257 (1974).
    [CrossRef]
  4. K. Sassen, “Depolarization of Laser Light Backscattered by Artificial Clouds,” J. Appl. Meteorol. 13, 921 (1974).
    [CrossRef]
  5. S. R. Pal, A. I. Carswell, “Polarization Properties of Lidar Backscattering from Clouds,” Appl. Opt. 12, 1530 (1973).
    [CrossRef] [PubMed]
  6. J. D. Houston, A. I. Carswell, “Four-Component Polarization Measurement of Lidar Atmospheric Scattering,” Appl. Opt. 17, 614 (1978).
    [CrossRef] [PubMed]
  7. K. N. Liou, R. M. Schotland, “Multiple Backscattering and Depolarization from Water Clouds for a Pulsed Lidar System,” J. Atmos. Sci. 28, 772 (1971).
    [CrossRef]
  8. E. W. Eloranta, “Calculation of Doubly Scattered Lidar Returns,” Ph.D. Dissertation, U. Wisconsin, Madison (1972), 115 pp.
  9. Q. Cai, K. N. Liou, “Theory of Time-Dependent Multiple Backscattering from Clouds,” J. Atmos. Sci. 38, 1452 (1981).
    [CrossRef]
  10. J. S. Ryan, S. R. Pal, A. I. Carswell, “Laser Backscattering from Dense Water-Droplet Clouds,” J. Opt. Soc. Am. 69, 60 (1979).
    [CrossRef]
  11. K. Sassen, K. N. Liou, “Scattering of Polarized Laser Light by Water Droplet, Mixed-Phase and Ice Crystal Clouds, Part II: Angular Depolarizing and Multiple-Scattering Behavior,” J. Atmos. Sci. 36, 852 (1979).
    [CrossRef]
  12. S. R. Pal, A. I. Carswell, “Polarization Anisotropy in Lidar Multiple Scattering from Atmospheric Clouds,” Appl. Opt. 24, 3464 (1985).
    [CrossRef] [PubMed]
  13. A. I. Carswell, S. R. Pal, “Polarization Anisotropy in Lidar Multiple Scattering from Clouds,” Appl. Opt. 19, 4123 (1980).
    [CrossRef] [PubMed]
  14. M. Kerker, The Scattering of Light and Other Electromagnetic Radiation (Academic, New York, 1969).
  15. Multiple-scattering calculations based on a number of measured cloud droplet size distributions were reported in K. N. Liou, “On Depolarization of Visible Light from Water Clouds for Monostatic Lidar,” J. Atmos. Sci. 29, 1000 (1972). Otherwise, gamma-type size distributions devised by Deirmendjian (see Ref. 1) to represent atmospheric clouds were used.
    [CrossRef]
  16. K. Sassen, G. C. Dodd, “Lidar Crossover Function and Misalignment Effects,” Appl. Opt. 21, 3167 (1982).
    [CrossRef]
  17. V. Ray Noonkester, “Profiles of Optical Extinction Coefficients Calculated from Droplet Spectra Observed in Marine Stratus Cloud Layers,” J. Atmos. Sci. 42, 1161 (1985).
    [CrossRef]
  18. S. T. Shipley, E. W. Eloranta, J. A. Weinman, “Measurement of Rainfall Rates by Lidar,” J. Appl. Meteorol. 13, 800 (1974).
    [CrossRef]
  19. G. C. Mooradian, M. Geller, L. B. Stotts, D. H. Stephans, R. A. Krautwald, “Blue-Green Pulsed Propagation Through Fog,” Appl. Opt. 18, 429 (1979).
    [CrossRef] [PubMed]
  20. C. M. R. Platt, “Remote Sounding of High Clouds. Ill: Monte Carlo Calculations of Multiple-Scattered Lidar Returns,” J. Atmos. Sci. 38, 156 (1981).
    [CrossRef]
  21. H. R. Pruppacher, J. D. Klett, Microphysics of Clouds and Precipitation (Reidel, Boston, 1980).
  22. R. T. Ryan, H. H. Blau, P. C. von Thuna, M. L. Cohen, “Cloud Microstructure as Determined by an Optical Cloud Particle Spectrometer,” J. Appl. Meteorol. 11, 149 (1972).
    [CrossRef]
  23. V. R. Noonkester, “Droplet Spectra Observed in Marine Stratus Cloud Layers,” J. Atmos. Sci. 41, 829 (1984).
    [CrossRef]
  24. J. Goodman, “The Microstructure of California Coastal Fog and Stratus,” J. Appl. Meteorol. 16, 1056 (1977).
    [CrossRef]
  25. H. C. van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957) discusses the general dependence of multiple scattering on optical thickness.
  26. A. Cohen, “Cloud-Base Water Content Measurement Using Single Wavelength Laser-Radar Data,” Appl. Opt. 14, 2873 (1975).
    [CrossRef] [PubMed]
  27. S. R. Pal, A. I. Carswell, “Multiple Scattering in Atmospheric Clouds: Lidar Observations,” Appl. Opt. 15, 1990 (1976).
    [CrossRef] [PubMed]
  28. Theoretical multiple-scattering simulations have largely adapted the convention of a 1.0-km distance to cloud base. Recent airborne lidar studies from a high-altitude aircraft described in J. D. Spinhirne, M. Z. Hansen, J. Simpson, “The Structure and Phase of Cloud Tops as Observed by Polarization Lidar,” J. Clim Appl. Meteorol. 22, 1319 (1983), obtained unexpectedly strong δ value increases from droplet multiple scattering which they attributed to the increased range factor.
    [CrossRef]

1985

S. R. Pal, A. I. Carswell, “Polarization Anisotropy in Lidar Multiple Scattering from Atmospheric Clouds,” Appl. Opt. 24, 3464 (1985).
[CrossRef] [PubMed]

V. Ray Noonkester, “Profiles of Optical Extinction Coefficients Calculated from Droplet Spectra Observed in Marine Stratus Cloud Layers,” J. Atmos. Sci. 42, 1161 (1985).
[CrossRef]

1984

V. R. Noonkester, “Droplet Spectra Observed in Marine Stratus Cloud Layers,” J. Atmos. Sci. 41, 829 (1984).
[CrossRef]

1983

Theoretical multiple-scattering simulations have largely adapted the convention of a 1.0-km distance to cloud base. Recent airborne lidar studies from a high-altitude aircraft described in J. D. Spinhirne, M. Z. Hansen, J. Simpson, “The Structure and Phase of Cloud Tops as Observed by Polarization Lidar,” J. Clim Appl. Meteorol. 22, 1319 (1983), obtained unexpectedly strong δ value increases from droplet multiple scattering which they attributed to the increased range factor.
[CrossRef]

1982

K. Sassen, G. C. Dodd, “Lidar Crossover Function and Misalignment Effects,” Appl. Opt. 21, 3167 (1982).
[CrossRef]

1981

C. M. R. Platt, “Remote Sounding of High Clouds. Ill: Monte Carlo Calculations of Multiple-Scattered Lidar Returns,” J. Atmos. Sci. 38, 156 (1981).
[CrossRef]

Q. Cai, K. N. Liou, “Theory of Time-Dependent Multiple Backscattering from Clouds,” J. Atmos. Sci. 38, 1452 (1981).
[CrossRef]

1980

1979

J. S. Ryan, S. R. Pal, A. I. Carswell, “Laser Backscattering from Dense Water-Droplet Clouds,” J. Opt. Soc. Am. 69, 60 (1979).
[CrossRef]

K. Sassen, K. N. Liou, “Scattering of Polarized Laser Light by Water Droplet, Mixed-Phase and Ice Crystal Clouds, Part II: Angular Depolarizing and Multiple-Scattering Behavior,” J. Atmos. Sci. 36, 852 (1979).
[CrossRef]

G. C. Mooradian, M. Geller, L. B. Stotts, D. H. Stephans, R. A. Krautwald, “Blue-Green Pulsed Propagation Through Fog,” Appl. Opt. 18, 429 (1979).
[CrossRef] [PubMed]

1978

1977

J. Goodman, “The Microstructure of California Coastal Fog and Stratus,” J. Appl. Meteorol. 16, 1056 (1977).
[CrossRef]

1976

1975

1974

S. T. Shipley, E. W. Eloranta, J. A. Weinman, “Measurement of Rainfall Rates by Lidar,” J. Appl. Meteorol. 13, 800 (1974).
[CrossRef]

K. N. Liou, H. Lahore, “Laser Sensing of Cloud Composition: A Backscattered Depolarization Technique,” J. Appl. Meteorol. 13, 257 (1974).
[CrossRef]

K. Sassen, “Depolarization of Laser Light Backscattered by Artificial Clouds,” J. Appl. Meteorol. 13, 921 (1974).
[CrossRef]

1973

1972

Multiple-scattering calculations based on a number of measured cloud droplet size distributions were reported in K. N. Liou, “On Depolarization of Visible Light from Water Clouds for Monostatic Lidar,” J. Atmos. Sci. 29, 1000 (1972). Otherwise, gamma-type size distributions devised by Deirmendjian (see Ref. 1) to represent atmospheric clouds were used.
[CrossRef]

R. T. Ryan, H. H. Blau, P. C. von Thuna, M. L. Cohen, “Cloud Microstructure as Determined by an Optical Cloud Particle Spectrometer,” J. Appl. Meteorol. 11, 149 (1972).
[CrossRef]

1971

R. M. Schotland, K. Sassen, R. Stone, “Observations by Lidar of Linear Depolarization Ratios for Hydrometeors,” J. Appl. Meteorol. 10, 1011 (1971).
[CrossRef]

K. N. Liou, R. M. Schotland, “Multiple Backscattering and Depolarization from Water Clouds for a Pulsed Lidar System,” J. Atmos. Sci. 28, 772 (1971).
[CrossRef]

Blau, H. H.

R. T. Ryan, H. H. Blau, P. C. von Thuna, M. L. Cohen, “Cloud Microstructure as Determined by an Optical Cloud Particle Spectrometer,” J. Appl. Meteorol. 11, 149 (1972).
[CrossRef]

Cai, Q.

Q. Cai, K. N. Liou, “Theory of Time-Dependent Multiple Backscattering from Clouds,” J. Atmos. Sci. 38, 1452 (1981).
[CrossRef]

Carswell, A. I.

Cohen, A.

Cohen, M. L.

R. T. Ryan, H. H. Blau, P. C. von Thuna, M. L. Cohen, “Cloud Microstructure as Determined by an Optical Cloud Particle Spectrometer,” J. Appl. Meteorol. 11, 149 (1972).
[CrossRef]

Deirmendjian, D.

D. Deirmendjian, Electromagnetic Scattering on Spherical Polydispersions (American Elsevier, New York, 1969).

Dodd, G. C.

K. Sassen, G. C. Dodd, “Lidar Crossover Function and Misalignment Effects,” Appl. Opt. 21, 3167 (1982).
[CrossRef]

Eloranta, E. W.

S. T. Shipley, E. W. Eloranta, J. A. Weinman, “Measurement of Rainfall Rates by Lidar,” J. Appl. Meteorol. 13, 800 (1974).
[CrossRef]

E. W. Eloranta, “Calculation of Doubly Scattered Lidar Returns,” Ph.D. Dissertation, U. Wisconsin, Madison (1972), 115 pp.

Geller, M.

Goodman, J.

J. Goodman, “The Microstructure of California Coastal Fog and Stratus,” J. Appl. Meteorol. 16, 1056 (1977).
[CrossRef]

Hansen, M. Z.

Theoretical multiple-scattering simulations have largely adapted the convention of a 1.0-km distance to cloud base. Recent airborne lidar studies from a high-altitude aircraft described in J. D. Spinhirne, M. Z. Hansen, J. Simpson, “The Structure and Phase of Cloud Tops as Observed by Polarization Lidar,” J. Clim Appl. Meteorol. 22, 1319 (1983), obtained unexpectedly strong δ value increases from droplet multiple scattering which they attributed to the increased range factor.
[CrossRef]

Houston, J. D.

Kerker, M.

M. Kerker, The Scattering of Light and Other Electromagnetic Radiation (Academic, New York, 1969).

Klett, J. D.

H. R. Pruppacher, J. D. Klett, Microphysics of Clouds and Precipitation (Reidel, Boston, 1980).

Krautwald, R. A.

Lahore, H.

K. N. Liou, H. Lahore, “Laser Sensing of Cloud Composition: A Backscattered Depolarization Technique,” J. Appl. Meteorol. 13, 257 (1974).
[CrossRef]

Liou, K. N.

Q. Cai, K. N. Liou, “Theory of Time-Dependent Multiple Backscattering from Clouds,” J. Atmos. Sci. 38, 1452 (1981).
[CrossRef]

K. Sassen, K. N. Liou, “Scattering of Polarized Laser Light by Water Droplet, Mixed-Phase and Ice Crystal Clouds, Part II: Angular Depolarizing and Multiple-Scattering Behavior,” J. Atmos. Sci. 36, 852 (1979).
[CrossRef]

K. N. Liou, H. Lahore, “Laser Sensing of Cloud Composition: A Backscattered Depolarization Technique,” J. Appl. Meteorol. 13, 257 (1974).
[CrossRef]

Multiple-scattering calculations based on a number of measured cloud droplet size distributions were reported in K. N. Liou, “On Depolarization of Visible Light from Water Clouds for Monostatic Lidar,” J. Atmos. Sci. 29, 1000 (1972). Otherwise, gamma-type size distributions devised by Deirmendjian (see Ref. 1) to represent atmospheric clouds were used.
[CrossRef]

K. N. Liou, R. M. Schotland, “Multiple Backscattering and Depolarization from Water Clouds for a Pulsed Lidar System,” J. Atmos. Sci. 28, 772 (1971).
[CrossRef]

Mooradian, G. C.

Noonkester, V. R.

V. R. Noonkester, “Droplet Spectra Observed in Marine Stratus Cloud Layers,” J. Atmos. Sci. 41, 829 (1984).
[CrossRef]

Pal, S. R.

Platt, C. M. R.

C. M. R. Platt, “Remote Sounding of High Clouds. Ill: Monte Carlo Calculations of Multiple-Scattered Lidar Returns,” J. Atmos. Sci. 38, 156 (1981).
[CrossRef]

Pruppacher, H. R.

H. R. Pruppacher, J. D. Klett, Microphysics of Clouds and Precipitation (Reidel, Boston, 1980).

Ray Noonkester, V.

V. Ray Noonkester, “Profiles of Optical Extinction Coefficients Calculated from Droplet Spectra Observed in Marine Stratus Cloud Layers,” J. Atmos. Sci. 42, 1161 (1985).
[CrossRef]

Ryan, J. S.

Ryan, R. T.

R. T. Ryan, H. H. Blau, P. C. von Thuna, M. L. Cohen, “Cloud Microstructure as Determined by an Optical Cloud Particle Spectrometer,” J. Appl. Meteorol. 11, 149 (1972).
[CrossRef]

Sassen, K.

K. Sassen, G. C. Dodd, “Lidar Crossover Function and Misalignment Effects,” Appl. Opt. 21, 3167 (1982).
[CrossRef]

K. Sassen, K. N. Liou, “Scattering of Polarized Laser Light by Water Droplet, Mixed-Phase and Ice Crystal Clouds, Part II: Angular Depolarizing and Multiple-Scattering Behavior,” J. Atmos. Sci. 36, 852 (1979).
[CrossRef]

K. Sassen, “Depolarization of Laser Light Backscattered by Artificial Clouds,” J. Appl. Meteorol. 13, 921 (1974).
[CrossRef]

R. M. Schotland, K. Sassen, R. Stone, “Observations by Lidar of Linear Depolarization Ratios for Hydrometeors,” J. Appl. Meteorol. 10, 1011 (1971).
[CrossRef]

Schotland, R. M.

R. M. Schotland, K. Sassen, R. Stone, “Observations by Lidar of Linear Depolarization Ratios for Hydrometeors,” J. Appl. Meteorol. 10, 1011 (1971).
[CrossRef]

K. N. Liou, R. M. Schotland, “Multiple Backscattering and Depolarization from Water Clouds for a Pulsed Lidar System,” J. Atmos. Sci. 28, 772 (1971).
[CrossRef]

Shipley, S. T.

S. T. Shipley, E. W. Eloranta, J. A. Weinman, “Measurement of Rainfall Rates by Lidar,” J. Appl. Meteorol. 13, 800 (1974).
[CrossRef]

Simpson, J.

Theoretical multiple-scattering simulations have largely adapted the convention of a 1.0-km distance to cloud base. Recent airborne lidar studies from a high-altitude aircraft described in J. D. Spinhirne, M. Z. Hansen, J. Simpson, “The Structure and Phase of Cloud Tops as Observed by Polarization Lidar,” J. Clim Appl. Meteorol. 22, 1319 (1983), obtained unexpectedly strong δ value increases from droplet multiple scattering which they attributed to the increased range factor.
[CrossRef]

Spinhirne, J. D.

Theoretical multiple-scattering simulations have largely adapted the convention of a 1.0-km distance to cloud base. Recent airborne lidar studies from a high-altitude aircraft described in J. D. Spinhirne, M. Z. Hansen, J. Simpson, “The Structure and Phase of Cloud Tops as Observed by Polarization Lidar,” J. Clim Appl. Meteorol. 22, 1319 (1983), obtained unexpectedly strong δ value increases from droplet multiple scattering which they attributed to the increased range factor.
[CrossRef]

Stephans, D. H.

Stone, R.

R. M. Schotland, K. Sassen, R. Stone, “Observations by Lidar of Linear Depolarization Ratios for Hydrometeors,” J. Appl. Meteorol. 10, 1011 (1971).
[CrossRef]

Stotts, L. B.

van de Hulst, H. C.

H. C. van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957) discusses the general dependence of multiple scattering on optical thickness.

von Thuna, P. C.

R. T. Ryan, H. H. Blau, P. C. von Thuna, M. L. Cohen, “Cloud Microstructure as Determined by an Optical Cloud Particle Spectrometer,” J. Appl. Meteorol. 11, 149 (1972).
[CrossRef]

Weinman, J. A.

S. T. Shipley, E. W. Eloranta, J. A. Weinman, “Measurement of Rainfall Rates by Lidar,” J. Appl. Meteorol. 13, 800 (1974).
[CrossRef]

Appl. Opt.

J. Appl. Meteorol.

J. Goodman, “The Microstructure of California Coastal Fog and Stratus,” J. Appl. Meteorol. 16, 1056 (1977).
[CrossRef]

R. T. Ryan, H. H. Blau, P. C. von Thuna, M. L. Cohen, “Cloud Microstructure as Determined by an Optical Cloud Particle Spectrometer,” J. Appl. Meteorol. 11, 149 (1972).
[CrossRef]

S. T. Shipley, E. W. Eloranta, J. A. Weinman, “Measurement of Rainfall Rates by Lidar,” J. Appl. Meteorol. 13, 800 (1974).
[CrossRef]

R. M. Schotland, K. Sassen, R. Stone, “Observations by Lidar of Linear Depolarization Ratios for Hydrometeors,” J. Appl. Meteorol. 10, 1011 (1971).
[CrossRef]

K. N. Liou, H. Lahore, “Laser Sensing of Cloud Composition: A Backscattered Depolarization Technique,” J. Appl. Meteorol. 13, 257 (1974).
[CrossRef]

K. Sassen, “Depolarization of Laser Light Backscattered by Artificial Clouds,” J. Appl. Meteorol. 13, 921 (1974).
[CrossRef]

J. Atmos. Sci.

Q. Cai, K. N. Liou, “Theory of Time-Dependent Multiple Backscattering from Clouds,” J. Atmos. Sci. 38, 1452 (1981).
[CrossRef]

K. N. Liou, R. M. Schotland, “Multiple Backscattering and Depolarization from Water Clouds for a Pulsed Lidar System,” J. Atmos. Sci. 28, 772 (1971).
[CrossRef]

Multiple-scattering calculations based on a number of measured cloud droplet size distributions were reported in K. N. Liou, “On Depolarization of Visible Light from Water Clouds for Monostatic Lidar,” J. Atmos. Sci. 29, 1000 (1972). Otherwise, gamma-type size distributions devised by Deirmendjian (see Ref. 1) to represent atmospheric clouds were used.
[CrossRef]

V. Ray Noonkester, “Profiles of Optical Extinction Coefficients Calculated from Droplet Spectra Observed in Marine Stratus Cloud Layers,” J. Atmos. Sci. 42, 1161 (1985).
[CrossRef]

K. Sassen, K. N. Liou, “Scattering of Polarized Laser Light by Water Droplet, Mixed-Phase and Ice Crystal Clouds, Part II: Angular Depolarizing and Multiple-Scattering Behavior,” J. Atmos. Sci. 36, 852 (1979).
[CrossRef]

V. R. Noonkester, “Droplet Spectra Observed in Marine Stratus Cloud Layers,” J. Atmos. Sci. 41, 829 (1984).
[CrossRef]

C. M. R. Platt, “Remote Sounding of High Clouds. Ill: Monte Carlo Calculations of Multiple-Scattered Lidar Returns,” J. Atmos. Sci. 38, 156 (1981).
[CrossRef]

J. Clim Appl. Meteorol.

Theoretical multiple-scattering simulations have largely adapted the convention of a 1.0-km distance to cloud base. Recent airborne lidar studies from a high-altitude aircraft described in J. D. Spinhirne, M. Z. Hansen, J. Simpson, “The Structure and Phase of Cloud Tops as Observed by Polarization Lidar,” J. Clim Appl. Meteorol. 22, 1319 (1983), obtained unexpectedly strong δ value increases from droplet multiple scattering which they attributed to the increased range factor.
[CrossRef]

J. Opt. Soc. Am.

Other

E. W. Eloranta, “Calculation of Doubly Scattered Lidar Returns,” Ph.D. Dissertation, U. Wisconsin, Madison (1972), 115 pp.

D. Deirmendjian, Electromagnetic Scattering on Spherical Polydispersions (American Elsevier, New York, 1969).

M. Kerker, The Scattering of Light and Other Electromagnetic Radiation (Academic, New York, 1969).

H. C. van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957) discusses the general dependence of multiple scattering on optical thickness.

H. R. Pruppacher, J. D. Klett, Microphysics of Clouds and Precipitation (Reidel, Boston, 1980).

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Figures (10)

Fig. 1
Fig. 1

Plots of azimuthally integrated depolarization ratio Δ(θ) and average phase function 1/2 [P1(θ) + P2(θ)] vs scattering angle for two logarithmically skewed cloud droplet distributions with the indicated modal radii αm and geometric mean standard deviations σ0

Fig. 2
Fig. 2

Satellite imagery of stratocumulus cloud conditions along the California coast on 10 June 1982 typical of the experimental period. The coastal field site was located west of the Salton Sea visible in southern California.

Fig. 3
Fig. 3

Height vs time display of lidar linear depolarization ratios (δ in percent) during the dissipation of a stratus cloud layer on 10 June 1982. Cloud base and apparent cloud top are indicated by the continuous and long dashed lines, respectively. Short dashed lines define enhanced aerosol returns from cloud element dissipation, and intermittent drizzle returns with near-zero δ values are shown beneath cloud base.

Fig. 4
Fig. 4

Linear depolarization ratio (in percent) and relative returned laser energy (in arbitrary units) profiles plotted as a function of vertical penetration depth above cloud base (in meters) for two consecutive lidar pulses using 1- and 3-mrad (MR) receiver beam-widths. The data were collected at a 90° elevation angle on 14 June 1982 from a cloud with a 480-m AGL cloud base.

Fig. 5
Fig. 5

As in Fig. 4 but for a 60° elevation angle and 450-m cloud base.

Fig. 6
Fig. 6

Data collected shortly after that shown in Fig. 4 under the same conditions.

Fig. 7
Fig. 7

As in Fig. 4 but for a markedly inhomogeneous cloud layer with a 410-m cloud base. Lidar elevation angle was 60°.

Fig. 8
Fig. 8

Linear depolarization ratios and relative returned energy profiles collected at 1-min intervals with a 3-mrad FOV at the three indicated lidar elevation angles plotted as a function of vertical penetration depth above cloud base. Average cloud base was 545 m.

Fig. 9
Fig. 9

Same data as in Fig. 8 but plotted as a function of slant path range into the cloud (in meters).

Fig. 10
Fig. 10

Effects of transmitter/receiver beam misalignment on linear depolarization ratios and returned laser energy profiles from a stratus cloud layer at 320 m above ground level. Numbers in the keys refer to the laser beam pointing error in mrad. Data were collected at 1-min intervals with a 1-mrad receiver FOV and at a 45° elevation angle.

Tables (1)

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Table I Ruby Ldar Specifications

Equations (6)

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δ ( ϕ ) = I ( ϕ ) I ( ϕ ) = [ ( k 2 k 1 ) sin ϕ cos ϕ ] 2 ( k 1 sin 2 ϕ + k 2 cos 2 ϕ ) 2 ,
k 1 = P 1 ( θ ) 1 / 2 , k 2 = P 2 ( θ ) 1 / 2 cos θ .
Î , = 0 π / 2 I , ( ϕ ) d ϕ , Î = π 16 ( k 2 k 1 ) 2 , Î = 3 π 16 ( k 1 2 + 2 3 k 1 k 2 + k 2 2 ) ,
Δ ( θ ) = Î Î = ( k 2 k 1 ) 2 3 ( k 1 2 + 2 3 k 1 k 2 + k 2 2 ) .
P ( R ) , = P t h A r 8 π R 2 f ( R ) β ( R ) , exp [ 2 0 R η ( R ) σ ( R ) d R ] ,
δ = P ( R ) P ( R ) ,

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