Abstract

This paper presents the results of investigations into the problems associated with modeling the atmospheric aerosol backscattering function βCO2 at CO2 laser wavelengths in the lowest 20 km of the atmosphere. It contains a summary of the relevant aerosol characteristics and their variability together with a discussion of the measurement techniques and the errors involved. The different methods of calculating βCO2 both from measured aerosol characteristics and from optical measurements made at other wavelengths are discussed in detail, and limits are placed on the accuracy of these methods. The most significant factor in determining βCO2 has been found to be the aerosol size distribution and concentration, which should be known accurately for particle radii up to at least 1 μm for stratospheric particles and 5 μm for tropospheric particles.

© 1983 Optical Society of America

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References

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  1. M. J. Post, F. F. Hall, R. A. Richter, T. R. Lawrence, Appl. Opt. 21, 2442 (1982).
    [CrossRef] [PubMed]
  2. G. H. Fichtl, J. W. Bilbro, D. Fitzgerrald, “Measurement of Wind Using an Airborne Doppler Lidar System (ADLS)—Results of 1981 CV-990 Flight Experiments,” in Conference Abstracts, Eleventh International Laser Radar Conference, Madison, Wisc., June 1982, pp. 179–182.
  3. R. M. Huffaker, Ed., “Feasibility Study of Satellite-Borne Lidar Global Wind Monitoring System,” NOAA Tech. Memo. ERR WPL-37 (1978).
  4. E. M. Patterson, D. A. Gillette, J. Geophys. Res. 82, 2074 (1977).
    [CrossRef]
  5. E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
    [CrossRef]
  6. G. S. Kent, Appl. Opt. 17, 3763 (1978).
    [CrossRef] [PubMed]
  7. D. J. Hofmann, J. M. Rosen, “Balloon-Borne Observations of Stratospheric Aerosol and Condensation Nuclei During the Year Following the Mount St. Helens Eruption,” U. Wyoming, Department of Physics and Astronomy, Report AP-63 (July1981).
  8. Aerosols and Climate, “Report on the Meeting of JSC Experts held in Geneva, 27–30 Oct. 1980,” WMO Report WCP-12 (1980).
  9. R. P. Turco, R. C. Whitten, O. B. Toon, Rev. Geophys. Space Phys. 30, 233 (1982).
    [CrossRef]
  10. G. M. Hale, M. R. Querry, Appl. Opt. 12, 555 (1973).
    [CrossRef] [PubMed]
  11. J. E. A. Selby, E. P. Shettle, R. A. McClatchey, “Atmospheric Transmittance from 0.25 to 28.5 μm: Supplement lowtran 3B,” AFGL-TR-76-0258, Environmental Research Papers 587, 1Nov.1976.
  12. E. P. Shettle, R. W. Fenn, “Models for the Aerosol of the Lower Atmosphere and the Effects of Humidity Variations on their Optical Properties,” Air Force Geophysical Laboratory, Hanscom Air Force Base, Mass., AFGL-TR-79-0214, Environmental Research Papers 676, 20Sept.1979.
  13. E. M. Patterson, J. Geophys. Res. 86, 3236 (1981).
    [CrossRef]
  14. K. F. Palmer, D. Williams, Appl. Opt. 14, 208 (1975).
    [PubMed]
  15. O. B. Toon, J. B. Pollack, B. N. Khare, J. Geophys. Res. 33, 5733 (1976).
    [CrossRef]
  16. F. E. Volz, Appl. Opt. 12, 564 (1973).
    [CrossRef] [PubMed]
  17. T. S. Cress, “Airborne Measurement of Aerosol Size Distributions Over Northern Europe,” Vol. 1. Spring and Fall, 1976, Summer 1977, Air Force Geophysical Laboratory, Hanscom Field, Mass., Environmental Research Paper 702 (29May1980).
  18. I. H. Blifford, J. Geophys. Res. 75, 3099 (1970).
    [CrossRef]
  19. D. L. Savoie, “Physical and Chemical Characteristics of Saharan Aerosolsover the Tropical North Atlantic,” Master’s Thesis, U. Miami (1978).
  20. R. C. Shirkey, A. Miller, G. H. Goedecke, Y. K. Bell, “Single Scattering Code agausx: Theory, Applications, Comparisons, and Listing,” U.S. Army Electronics Research and Development Command, Atmospheric Sciences Laboratory, Technical Report ASL-TR0062 (1980).
  21. D. C. Woods, “Examples of Realistic Aerosol Particles Collected in a Cascade Impactor,” in Light Scattered by Irregularly Shaped Particles, D. W. Schuerman, Ed. (Plenum, New York, 1979).
  22. J. B. Pollack, J. N. Cuzzi, “Scattering by Non-Spherical Particles of Size Comparable to a Wavelength: A New Semi-Empirical Theory,” in Light Scattering by Irregularly Shaped Particles, D. W. Schuerman (Plenum, New York1979), pp. 113–126.
  23. D. R. Huffman, C. F. Cohren, “Infrared Absorption Spectra of Non-Spherical Particles Treated in the Rayleigh-Ellipsoid Approximation,” in Light Scattering by Irregularly Shaped Particles, D. W. Schuerman, Ed. (Plenum, New York, 1979), pp. 103–112.
  24. M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
    [CrossRef]
  25. K. T. Whitby, “On the Multi-Model Nature of Atmospheric Aerosol Size Distribution,” presented at the Eighth International Conference on Nucleation, Leningrad, U.S.S.R., U. Minnesota, Mechanical Engineering Department, Particle Technology Laboratory Publication 218.
  26. J. L. Gras, G. P. Ayers, J. Appl. Meteorol. 18, 634 (1979).
    [CrossRef]
  27. J. L. Gras, J. E. Laby, J. Geophys. Res. 86, 9767 (1981).
    [CrossRef]
  28. G. K. Yue, G. S. Kent, U. O. Farrukh, A. Deepak, Appl. Opt. 22, 1671 (1983).
    [CrossRef] [PubMed]

1983 (1)

1982 (2)

M. J. Post, F. F. Hall, R. A. Richter, T. R. Lawrence, Appl. Opt. 21, 2442 (1982).
[CrossRef] [PubMed]

R. P. Turco, R. C. Whitten, O. B. Toon, Rev. Geophys. Space Phys. 30, 233 (1982).
[CrossRef]

1981 (2)

E. M. Patterson, J. Geophys. Res. 86, 3236 (1981).
[CrossRef]

J. L. Gras, J. E. Laby, J. Geophys. Res. 86, 9767 (1981).
[CrossRef]

1980 (1)

E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
[CrossRef]

1979 (2)

M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

J. L. Gras, G. P. Ayers, J. Appl. Meteorol. 18, 634 (1979).
[CrossRef]

1978 (1)

1977 (1)

E. M. Patterson, D. A. Gillette, J. Geophys. Res. 82, 2074 (1977).
[CrossRef]

1976 (1)

O. B. Toon, J. B. Pollack, B. N. Khare, J. Geophys. Res. 33, 5733 (1976).
[CrossRef]

1975 (1)

1973 (2)

1970 (1)

I. H. Blifford, J. Geophys. Res. 75, 3099 (1970).
[CrossRef]

Ayers, G. P.

J. L. Gras, G. P. Ayers, J. Appl. Meteorol. 18, 634 (1979).
[CrossRef]

Bell, Y. K.

R. C. Shirkey, A. Miller, G. H. Goedecke, Y. K. Bell, “Single Scattering Code agausx: Theory, Applications, Comparisons, and Listing,” U.S. Army Electronics Research and Development Command, Atmospheric Sciences Laboratory, Technical Report ASL-TR0062 (1980).

Bilbro, J. W.

G. H. Fichtl, J. W. Bilbro, D. Fitzgerrald, “Measurement of Wind Using an Airborne Doppler Lidar System (ADLS)—Results of 1981 CV-990 Flight Experiments,” in Conference Abstracts, Eleventh International Laser Radar Conference, Madison, Wisc., June 1982, pp. 179–182.

Blifford, I. H.

I. H. Blifford, J. Geophys. Res. 75, 3099 (1970).
[CrossRef]

Chu, W. P.

M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Cohren, C. F.

D. R. Huffman, C. F. Cohren, “Infrared Absorption Spectra of Non-Spherical Particles Treated in the Rayleigh-Ellipsoid Approximation,” in Light Scattering by Irregularly Shaped Particles, D. W. Schuerman, Ed. (Plenum, New York, 1979), pp. 103–112.

Cress, T. S.

T. S. Cress, “Airborne Measurement of Aerosol Size Distributions Over Northern Europe,” Vol. 1. Spring and Fall, 1976, Summer 1977, Air Force Geophysical Laboratory, Hanscom Field, Mass., Environmental Research Paper 702 (29May1980).

Cuzzi, J. N.

J. B. Pollack, J. N. Cuzzi, “Scattering by Non-Spherical Particles of Size Comparable to a Wavelength: A New Semi-Empirical Theory,” in Light Scattering by Irregularly Shaped Particles, D. W. Schuerman (Plenum, New York1979), pp. 113–126.

Deepak, A.

Delany, A. C.

E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
[CrossRef]

Farrukh, U. O.

Fenn, R. W.

E. P. Shettle, R. W. Fenn, “Models for the Aerosol of the Lower Atmosphere and the Effects of Humidity Variations on their Optical Properties,” Air Force Geophysical Laboratory, Hanscom Air Force Base, Mass., AFGL-TR-79-0214, Environmental Research Papers 676, 20Sept.1979.

Fichtl, G. H.

G. H. Fichtl, J. W. Bilbro, D. Fitzgerrald, “Measurement of Wind Using an Airborne Doppler Lidar System (ADLS)—Results of 1981 CV-990 Flight Experiments,” in Conference Abstracts, Eleventh International Laser Radar Conference, Madison, Wisc., June 1982, pp. 179–182.

Fitzgerrald, D.

G. H. Fichtl, J. W. Bilbro, D. Fitzgerrald, “Measurement of Wind Using an Airborne Doppler Lidar System (ADLS)—Results of 1981 CV-990 Flight Experiments,” in Conference Abstracts, Eleventh International Laser Radar Conference, Madison, Wisc., June 1982, pp. 179–182.

Gillette, D. A.

E. M. Patterson, D. A. Gillette, J. Geophys. Res. 82, 2074 (1977).
[CrossRef]

Goedecke, G. H.

R. C. Shirkey, A. Miller, G. H. Goedecke, Y. K. Bell, “Single Scattering Code agausx: Theory, Applications, Comparisons, and Listing,” U.S. Army Electronics Research and Development Command, Atmospheric Sciences Laboratory, Technical Report ASL-TR0062 (1980).

Gras, J. L.

J. L. Gras, J. E. Laby, J. Geophys. Res. 86, 9767 (1981).
[CrossRef]

J. L. Gras, G. P. Ayers, J. Appl. Meteorol. 18, 634 (1979).
[CrossRef]

Hale, G. M.

Hall, F. F.

Hamill, P.

M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Hofmann, D. J.

D. J. Hofmann, J. M. Rosen, “Balloon-Borne Observations of Stratospheric Aerosol and Condensation Nuclei During the Year Following the Mount St. Helens Eruption,” U. Wyoming, Department of Physics and Astronomy, Report AP-63 (July1981).

Huebert, B. J.

E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
[CrossRef]

Huffman, D. R.

D. R. Huffman, C. F. Cohren, “Infrared Absorption Spectra of Non-Spherical Particles Treated in the Rayleigh-Ellipsoid Approximation,” in Light Scattering by Irregularly Shaped Particles, D. W. Schuerman, Ed. (Plenum, New York, 1979), pp. 103–112.

Kent, G. S.

Khare, B. N.

O. B. Toon, J. B. Pollack, B. N. Khare, J. Geophys. Res. 33, 5733 (1976).
[CrossRef]

Kiang, C. S.

E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
[CrossRef]

Laby, J. E.

J. L. Gras, J. E. Laby, J. Geophys. Res. 86, 9767 (1981).
[CrossRef]

Lawrence, T. R.

Leslie, A. C. D.

E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
[CrossRef]

McClatchey, R. A.

J. E. A. Selby, E. P. Shettle, R. A. McClatchey, “Atmospheric Transmittance from 0.25 to 28.5 μm: Supplement lowtran 3B,” AFGL-TR-76-0258, Environmental Research Papers 587, 1Nov.1976.

McCormick, M. P.

M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

McMaster, L. R.

M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Miller, A.

R. C. Shirkey, A. Miller, G. H. Goedecke, Y. K. Bell, “Single Scattering Code agausx: Theory, Applications, Comparisons, and Listing,” U.S. Army Electronics Research and Development Command, Atmospheric Sciences Laboratory, Technical Report ASL-TR0062 (1980).

Palmer, K. F.

Patterson, E. M.

E. M. Patterson, J. Geophys. Res. 86, 3236 (1981).
[CrossRef]

E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
[CrossRef]

E. M. Patterson, D. A. Gillette, J. Geophys. Res. 82, 2074 (1977).
[CrossRef]

Pepin, T. J.

M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Pollack, J. B.

O. B. Toon, J. B. Pollack, B. N. Khare, J. Geophys. Res. 33, 5733 (1976).
[CrossRef]

J. B. Pollack, J. N. Cuzzi, “Scattering by Non-Spherical Particles of Size Comparable to a Wavelength: A New Semi-Empirical Theory,” in Light Scattering by Irregularly Shaped Particles, D. W. Schuerman (Plenum, New York1979), pp. 113–126.

Post, M. J.

Querry, M. R.

Richter, R. A.

Rosen, J. M.

D. J. Hofmann, J. M. Rosen, “Balloon-Borne Observations of Stratospheric Aerosol and Condensation Nuclei During the Year Following the Mount St. Helens Eruption,” U. Wyoming, Department of Physics and Astronomy, Report AP-63 (July1981).

Savoie, D. L.

D. L. Savoie, “Physical and Chemical Characteristics of Saharan Aerosolsover the Tropical North Atlantic,” Master’s Thesis, U. Miami (1978).

Selby, J. E. A.

J. E. A. Selby, E. P. Shettle, R. A. McClatchey, “Atmospheric Transmittance from 0.25 to 28.5 μm: Supplement lowtran 3B,” AFGL-TR-76-0258, Environmental Research Papers 587, 1Nov.1976.

Shettle, E. P.

J. E. A. Selby, E. P. Shettle, R. A. McClatchey, “Atmospheric Transmittance from 0.25 to 28.5 μm: Supplement lowtran 3B,” AFGL-TR-76-0258, Environmental Research Papers 587, 1Nov.1976.

E. P. Shettle, R. W. Fenn, “Models for the Aerosol of the Lower Atmosphere and the Effects of Humidity Variations on their Optical Properties,” Air Force Geophysical Laboratory, Hanscom Air Force Base, Mass., AFGL-TR-79-0214, Environmental Research Papers 676, 20Sept.1979.

Shirkey, R. C.

R. C. Shirkey, A. Miller, G. H. Goedecke, Y. K. Bell, “Single Scattering Code agausx: Theory, Applications, Comparisons, and Listing,” U.S. Army Electronics Research and Development Command, Atmospheric Sciences Laboratory, Technical Report ASL-TR0062 (1980).

Swissler, T. J.

M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

Toon, O. B.

R. P. Turco, R. C. Whitten, O. B. Toon, Rev. Geophys. Space Phys. 30, 233 (1982).
[CrossRef]

O. B. Toon, J. B. Pollack, B. N. Khare, J. Geophys. Res. 33, 5733 (1976).
[CrossRef]

Turco, R. P.

R. P. Turco, R. C. Whitten, O. B. Toon, Rev. Geophys. Space Phys. 30, 233 (1982).
[CrossRef]

Volz, F. E.

Wartburg, A. F.

E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
[CrossRef]

Whitby, K. T.

K. T. Whitby, “On the Multi-Model Nature of Atmospheric Aerosol Size Distribution,” presented at the Eighth International Conference on Nucleation, Leningrad, U.S.S.R., U. Minnesota, Mechanical Engineering Department, Particle Technology Laboratory Publication 218.

Whitten, R. C.

R. P. Turco, R. C. Whitten, O. B. Toon, Rev. Geophys. Space Phys. 30, 233 (1982).
[CrossRef]

Williams, D.

Woods, D. C.

D. C. Woods, “Examples of Realistic Aerosol Particles Collected in a Cascade Impactor,” in Light Scattered by Irregularly Shaped Particles, D. W. Schuerman, Ed. (Plenum, New York, 1979).

Yue, G. K.

Appl. Opt. (6)

Bull. Am. Meteorol. Soc. (1)

M. P. McCormick, P. Hamill, T. J. Pepin, W. P. Chu, T. J. Swissler, L. R. McMaster, Bull. Am. Meteorol. Soc. 60, 1038 (1979).
[CrossRef]

J. Appl. Meteorol. (1)

J. L. Gras, G. P. Ayers, J. Appl. Meteorol. 18, 634 (1979).
[CrossRef]

J. Geophys. Res. (6)

J. L. Gras, J. E. Laby, J. Geophys. Res. 86, 9767 (1981).
[CrossRef]

I. H. Blifford, J. Geophys. Res. 75, 3099 (1970).
[CrossRef]

E. M. Patterson, D. A. Gillette, J. Geophys. Res. 82, 2074 (1977).
[CrossRef]

E. M. Patterson, C. S. Kiang, A. C. Delany, A. F. Wartburg, A. C. D. Leslie, B. J. Huebert, J. Geophys. Res. 85, 7361 (1980).
[CrossRef]

E. M. Patterson, J. Geophys. Res. 86, 3236 (1981).
[CrossRef]

O. B. Toon, J. B. Pollack, B. N. Khare, J. Geophys. Res. 33, 5733 (1976).
[CrossRef]

Rev. Geophys. Space Phys. (1)

R. P. Turco, R. C. Whitten, O. B. Toon, Rev. Geophys. Space Phys. 30, 233 (1982).
[CrossRef]

Other (13)

T. S. Cress, “Airborne Measurement of Aerosol Size Distributions Over Northern Europe,” Vol. 1. Spring and Fall, 1976, Summer 1977, Air Force Geophysical Laboratory, Hanscom Field, Mass., Environmental Research Paper 702 (29May1980).

G. H. Fichtl, J. W. Bilbro, D. Fitzgerrald, “Measurement of Wind Using an Airborne Doppler Lidar System (ADLS)—Results of 1981 CV-990 Flight Experiments,” in Conference Abstracts, Eleventh International Laser Radar Conference, Madison, Wisc., June 1982, pp. 179–182.

R. M. Huffaker, Ed., “Feasibility Study of Satellite-Borne Lidar Global Wind Monitoring System,” NOAA Tech. Memo. ERR WPL-37 (1978).

D. J. Hofmann, J. M. Rosen, “Balloon-Borne Observations of Stratospheric Aerosol and Condensation Nuclei During the Year Following the Mount St. Helens Eruption,” U. Wyoming, Department of Physics and Astronomy, Report AP-63 (July1981).

Aerosols and Climate, “Report on the Meeting of JSC Experts held in Geneva, 27–30 Oct. 1980,” WMO Report WCP-12 (1980).

D. L. Savoie, “Physical and Chemical Characteristics of Saharan Aerosolsover the Tropical North Atlantic,” Master’s Thesis, U. Miami (1978).

R. C. Shirkey, A. Miller, G. H. Goedecke, Y. K. Bell, “Single Scattering Code agausx: Theory, Applications, Comparisons, and Listing,” U.S. Army Electronics Research and Development Command, Atmospheric Sciences Laboratory, Technical Report ASL-TR0062 (1980).

D. C. Woods, “Examples of Realistic Aerosol Particles Collected in a Cascade Impactor,” in Light Scattered by Irregularly Shaped Particles, D. W. Schuerman, Ed. (Plenum, New York, 1979).

J. B. Pollack, J. N. Cuzzi, “Scattering by Non-Spherical Particles of Size Comparable to a Wavelength: A New Semi-Empirical Theory,” in Light Scattering by Irregularly Shaped Particles, D. W. Schuerman (Plenum, New York1979), pp. 113–126.

D. R. Huffman, C. F. Cohren, “Infrared Absorption Spectra of Non-Spherical Particles Treated in the Rayleigh-Ellipsoid Approximation,” in Light Scattering by Irregularly Shaped Particles, D. W. Schuerman, Ed. (Plenum, New York, 1979), pp. 103–112.

J. E. A. Selby, E. P. Shettle, R. A. McClatchey, “Atmospheric Transmittance from 0.25 to 28.5 μm: Supplement lowtran 3B,” AFGL-TR-76-0258, Environmental Research Papers 587, 1Nov.1976.

E. P. Shettle, R. W. Fenn, “Models for the Aerosol of the Lower Atmosphere and the Effects of Humidity Variations on their Optical Properties,” Air Force Geophysical Laboratory, Hanscom Air Force Base, Mass., AFGL-TR-79-0214, Environmental Research Papers 676, 20Sept.1979.

K. T. Whitby, “On the Multi-Model Nature of Atmospheric Aerosol Size Distribution,” presented at the Eighth International Conference on Nucleation, Leningrad, U.S.S.R., U. Minnesota, Mechanical Engineering Department, Particle Technology Laboratory Publication 218.

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Figures (13)

Fig. 1
Fig. 1

Typical examples of aerosol size distribution in different regions of the atmosphere: (a) boundary layer; (b) free troposphere; (c) stratosphere.

Fig. 2
Fig. 2

Altitude variation of large particle concentrations (r > 0.2 μm) over Europe (Cress17).

Fig. 3
Fig. 3

Volume size distributions measured by different research workers over land and ocean (Blifford18; Savoie19; Patterson et al.5).

Fig. 4
Fig. 4

Cumulative probability distributions for the aerosol particle concentrations over Europe (Cress17). N/Nm represents the ratio of the aerosol number concentration to the mean concentration measured over a 9-month period.

Fig. 5
Fig. 5

Example of aerosol size distribution measurements showing statistical noise at the larger radii particles (Cress17).

Fig. 6
Fig. 6

Size distributions selected as typical of those occurring in the free troposphere (Cress17; Patterson et al.5).

Fig. 7
Fig. 7

Histograms showing the relative backscatter at a wavelength of 10.6 μm from (a) Cress17 spring average size distribution; (b) Patterson et al.5 continental-free troposphere size distribution; (c) Patterson et al.5 marine-free troposphere size distribution.

Fig. 8
Fig. 8

Histograms showing the relative backscatter and extinction at four different wavelengths from different particle size ranges for the Patterson et al.5 continental-free troposphere size distribution.

Fig. 9
Fig. 9

Variation with mode radius of βCO2 for constant density for lognormal size distributions and five common aerosol materials.

Fig. 10
Fig. 10

βCO2 per unit volume of aerosol for lognormal size distributions shown as a function of number and volume mode radius.

Fig. 11
Fig. 11

(a) Cumulative aerosol size distributions taken from Hofmann and Rosen.7 Lognormal curves have been fitted to the three data points of smallest radii at each altitude. For the 16-km altitude data only, the lognormal curve has been broken, and additional straight lines are drawn connecting the data points for the larger radii particles. (b) Enlarged view of the large particle end of the size distribution shown in Fig. 11(a). (c) Contributions to βCO2 for the Hofmann and Rosen cumulative size distribution at a height of 16 km shown in Fig. 11(a).

Fig. 12
Fig. 12

(a) Backscatter to extinction ratios β10.6/σ1.00 shown as a function of lognormal mode radius; (b) histograms of the frequency of observation of various values of the ratio β10.6/σ1.00.

Fig. 13
Fig. 13

Variation of βCO2 with refractive index: (a) for the Cress17 spring average size distribution; (b) for the Patterson et al.5 continental size distribution; (c) for the Patterson et al.5 marine-free troposphere size distribution.

Tables (4)

Tables Icon

Table I Refractive Indices of Common Aerosol Materials

Tables Icon

Table II Comparison of βCO2 Values Calculated from the Lower and Upper Envelopes of the Reported Aerosol Size Distributions with Noise at the Large Particle Enda

Tables Icon

Table III Comparison of βCO2 Values Calculated from Aerosol Size Distributions Deduced with Different Sizing Techniquesa

Tables Icon

Table IV Effect of Extrapolation on the Calculated Values of βCO2

Equations (2)

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β CO 2 = r 1 r 2 Q ( n , t ) [ d N ( α ) d r ] d r ,
d N ( r ) / d log ( r ) = A exp [ - ln 2 ( r / r m ) / ( 2 ln 2 σ g ) ] ,

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