Abstract

In urban Seattle, simultaneous measurements were made of backscatter using a ruby laser radar and of the scattering portion of extinction using an integrating nephelometer. Both instruments were calibrated allowing separation of molecular and aerosol contributions to the two scatter coefficients. During the period of the experiment, backscatter and the scattering portion of extinction were well correlated at relative humidities less than 70%. For the aerosol, the ratio of backscatter to the scattering portion of extinction was only one-third that predicted from spherical particle Mie calculations for a power law size distribution aerosol.

© 1972 Optical Society of America

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References

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  1. M. G. H. Ligda, Proceedings of the First Conference on Laser Technology (Secret), Office of Naval Research (1963).
  2. R. T. H. Collis, J. W. Oblanas, First Report of Contract 26-120, Forest Service, U.S.D.A. (1967).
  3. R. T. H. Collis, F. G. Fernald, J. Alder, J. Appl. Meteorol. 7, 227 (1968).
    [CrossRef]
  4. E. W. Barrett, O. Ben-Dov, J. Appl. Meteorol. 6, 500 (1967).
    [CrossRef]
  5. E. B. de Bary, B. Braun, K. Bullrich, Special Report33, AFCRL (65-710) (1965).
  6. M. Bertolotti, L. Muzii, D. Sette, Appl. Opt. 8, 117 (1969).
    [CrossRef] [PubMed]
  7. F. F. Hall, H. Y. Ageno, Appl. Opt. 9, 1820 (1970).
    [CrossRef] [PubMed]
  8. M. P. McCormick, J. D. Lawrence, F. R. Crownfield, Appl. Opt. 7, 2424 (1968).
    [CrossRef] [PubMed]
  9. A. P. Waggoner, Ph.D. Dissertation, Geophysics, University of Washington, Seattle (1971).
  10. R. J. Beuttell, A. W. Brewer, J. Sci. Instrum. 26, 357 (1949).
    [CrossRef]
  11. W. E. K. Middleton, Vision Through the Atmosphere (University of Toronto Press, Toronto, 1958), Vol. 19, pp.203–205.
  12. N. C. Ahlquist, R. J. Charlson, Atmos. Environ. 3, 551 (1969).
    [CrossRef]
  13. D. E. Ensor, A. P. Waggoner, Atmos. Environ. 4, 481 (1970).
    [CrossRef]
  14. K. E. Noll, Master’s Thesis, Civil Engineering, University of Washington, Seattle (1966).
  15. K. T. Whitby, Particle Laboratory Publication141, University of Minnesota, Minneapolis (1970).
  16. H. C. Van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957), pp. 417–418.
  17. A. C. Holland, G. Gagné, Appl. Opt. 9, 1113 (1970).
    [CrossRef] [PubMed]
  18. R. W. Fenn, Appl. Opt. 5, 293 (1966).
    [CrossRef] [PubMed]
  19. S. Twomey, H. B. Howell, Appl. Opt. 4, 501 (1965).
    [CrossRef]

1970 (3)

1969 (2)

M. Bertolotti, L. Muzii, D. Sette, Appl. Opt. 8, 117 (1969).
[CrossRef] [PubMed]

N. C. Ahlquist, R. J. Charlson, Atmos. Environ. 3, 551 (1969).
[CrossRef]

1968 (2)

M. P. McCormick, J. D. Lawrence, F. R. Crownfield, Appl. Opt. 7, 2424 (1968).
[CrossRef] [PubMed]

R. T. H. Collis, F. G. Fernald, J. Alder, J. Appl. Meteorol. 7, 227 (1968).
[CrossRef]

1967 (1)

E. W. Barrett, O. Ben-Dov, J. Appl. Meteorol. 6, 500 (1967).
[CrossRef]

1966 (1)

1965 (1)

1949 (1)

R. J. Beuttell, A. W. Brewer, J. Sci. Instrum. 26, 357 (1949).
[CrossRef]

Ageno, H. Y.

Ahlquist, N. C.

N. C. Ahlquist, R. J. Charlson, Atmos. Environ. 3, 551 (1969).
[CrossRef]

Alder, J.

R. T. H. Collis, F. G. Fernald, J. Alder, J. Appl. Meteorol. 7, 227 (1968).
[CrossRef]

Barrett, E. W.

E. W. Barrett, O. Ben-Dov, J. Appl. Meteorol. 6, 500 (1967).
[CrossRef]

Ben-Dov, O.

E. W. Barrett, O. Ben-Dov, J. Appl. Meteorol. 6, 500 (1967).
[CrossRef]

Bertolotti, M.

Beuttell, R. J.

R. J. Beuttell, A. W. Brewer, J. Sci. Instrum. 26, 357 (1949).
[CrossRef]

Braun, B.

E. B. de Bary, B. Braun, K. Bullrich, Special Report33, AFCRL (65-710) (1965).

Brewer, A. W.

R. J. Beuttell, A. W. Brewer, J. Sci. Instrum. 26, 357 (1949).
[CrossRef]

Bullrich, K.

E. B. de Bary, B. Braun, K. Bullrich, Special Report33, AFCRL (65-710) (1965).

Charlson, R. J.

N. C. Ahlquist, R. J. Charlson, Atmos. Environ. 3, 551 (1969).
[CrossRef]

Collis, R. T. H.

R. T. H. Collis, F. G. Fernald, J. Alder, J. Appl. Meteorol. 7, 227 (1968).
[CrossRef]

R. T. H. Collis, J. W. Oblanas, First Report of Contract 26-120, Forest Service, U.S.D.A. (1967).

Crownfield, F. R.

de Bary, E. B.

E. B. de Bary, B. Braun, K. Bullrich, Special Report33, AFCRL (65-710) (1965).

Ensor, D. E.

D. E. Ensor, A. P. Waggoner, Atmos. Environ. 4, 481 (1970).
[CrossRef]

Fenn, R. W.

Fernald, F. G.

R. T. H. Collis, F. G. Fernald, J. Alder, J. Appl. Meteorol. 7, 227 (1968).
[CrossRef]

Gagné, G.

Hall, F. F.

Holland, A. C.

Howell, H. B.

Lawrence, J. D.

Ligda, M. G. H.

M. G. H. Ligda, Proceedings of the First Conference on Laser Technology (Secret), Office of Naval Research (1963).

McCormick, M. P.

Middleton, W. E. K.

W. E. K. Middleton, Vision Through the Atmosphere (University of Toronto Press, Toronto, 1958), Vol. 19, pp.203–205.

Muzii, L.

Noll, K. E.

K. E. Noll, Master’s Thesis, Civil Engineering, University of Washington, Seattle (1966).

Oblanas, J. W.

R. T. H. Collis, J. W. Oblanas, First Report of Contract 26-120, Forest Service, U.S.D.A. (1967).

Sette, D.

Twomey, S.

Van de Hulst, H. C.

H. C. Van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957), pp. 417–418.

Waggoner, A. P.

D. E. Ensor, A. P. Waggoner, Atmos. Environ. 4, 481 (1970).
[CrossRef]

A. P. Waggoner, Ph.D. Dissertation, Geophysics, University of Washington, Seattle (1971).

Whitby, K. T.

K. T. Whitby, Particle Laboratory Publication141, University of Minnesota, Minneapolis (1970).

Appl. Opt. (6)

Atmos. Environ. (2)

N. C. Ahlquist, R. J. Charlson, Atmos. Environ. 3, 551 (1969).
[CrossRef]

D. E. Ensor, A. P. Waggoner, Atmos. Environ. 4, 481 (1970).
[CrossRef]

J. Appl. Meteorol. (2)

R. T. H. Collis, F. G. Fernald, J. Alder, J. Appl. Meteorol. 7, 227 (1968).
[CrossRef]

E. W. Barrett, O. Ben-Dov, J. Appl. Meteorol. 6, 500 (1967).
[CrossRef]

J. Sci. Instrum. (1)

R. J. Beuttell, A. W. Brewer, J. Sci. Instrum. 26, 357 (1949).
[CrossRef]

Other (8)

W. E. K. Middleton, Vision Through the Atmosphere (University of Toronto Press, Toronto, 1958), Vol. 19, pp.203–205.

K. E. Noll, Master’s Thesis, Civil Engineering, University of Washington, Seattle (1966).

K. T. Whitby, Particle Laboratory Publication141, University of Minnesota, Minneapolis (1970).

H. C. Van de Hulst, Light Scattering by Small Particles (Wiley, New York, 1957), pp. 417–418.

E. B. de Bary, B. Braun, K. Bullrich, Special Report33, AFCRL (65-710) (1965).

M. G. H. Ligda, Proceedings of the First Conference on Laser Technology (Secret), Office of Naval Research (1963).

R. T. H. Collis, J. W. Oblanas, First Report of Contract 26-120, Forest Service, U.S.D.A. (1967).

A. P. Waggoner, Ph.D. Dissertation, Geophysics, University of Washington, Seattle (1971).

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Figures (5)

Fig. 1
Fig. 1

Predicted relationship of σ and β from Eq. (8). The values of the two Rayleigh scattering coefficients are noted on the respective axes.

Fig. 2
Fig. 2

Block diagram of lidar data system.

Fig. 3
Fig. 3

Plot of the measured relationship of β and σ. Data taken at relative humidity above 75% are shown as open circles. The regression line is a least-squares fit to the data and is terminated at the Rayleigh scatter point.

Fig. 4
Fig. 4

Ratio of measured backscatter to that predicted by the regression line plotted as a function of relative humidity.

Fig. 5
Fig. 5

Variability of wavelength dependence of σ, in terms of the parameter α defined in Eq. (11). From the measured wavelength dependence, the exponent ν of the size distribution can be inferred through Eq. (12).

Tables (1)

Tables Icon

Table I Values of the Scattering Ratio A

Equations (13)

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β = d σ / d Ω at θ = 180° .
P R ( r ) = Const . ( β / r 2 ) e - 2 0 r σ ( x ) d x ,
β Total = β Aerosol + β Rayleigh ,
σ Total = σ Aerosol + σ Rayleigh .
β Aerosol = A σ Aerosol / 4 π ,
β Total = ( A σ Aerosol / 4 π ) + β Rayleigh
β Total = ( A σ Total / 4 π ) - ( A σ Rayleigh / 4 π ) + β Rayleigh .
β Total = ( A σ Total / 4 π ) + constant terms ,
β = 0.55 × 10 - 6 M - 1 Ω - 1 ,             σ = 4.6 × 10 - 6 M - 1 .
β Total = β Rayleigh + [ ( 0.15 ± 0.02 ) σ Aerosol / 4 π ] .
d n / d r = C r - ( ν + 1 ) r 1 < r < r 2 .
σ = Const . λ - α ,
α = ν - 2. 16

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