Abstract

The meteorological optical range (MOR) is the greatest distance at which a nonluminous object is barely discernible. Koschmieder related the optical atmospheric extinction coefficient to the contrast between the object and its background. His law assumes a uniform atmosphere and yields an isotropic value of the MOR. The model presented here incorporates the effect of anisotropic atmospheric brightness on contrast (and thus on the MOR). The Koschmieder MOR is then decreased by a factor according to the brightness prevailing in the direction of assessment. Manual assessments of the MOR made in arbitrary directions are shown to agree satisfactorily with the derated MOR. Minor modifications to existing instruments at airports would enable the instruments to register true values of the MOR and the runway visual range in directions relevant to the pilot, i.e., along the runway.

© 2005 Optical Society of America

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References

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  1. W. E. K. Middleton, Vision through the Atmosphere (U. Toronto Press, Toronto, Ontario, Canada, 1952), Chap. 4, p. 62.
  2. H. R. Blackwell, “Contrast thresholds of the human eye,” J. Opt. Soc. Am. 36, 624–643 (1946).
    [CrossRef] [PubMed]
  3. Secretariat of the World Meteorological Organization, Guide to Meteorological Instruments and Methods of Observation, 5th ed., WMO document 8 (World Meteorological Organization, Geneva, Switzerland, 1983), Chaps. 10 and 16, pp. 10.1–10.15, 16.4–16.7.
  4. International Civil Aviation Organization, Manual of Runway Visual Range Observing and Reporting Practices, 2nd ed., document 9328-AN/908 (International Civil Aviation Organization, Montreal, Quebec, Canada, 2000).
  5. A. P. Ginsburg, Vision Sciences Research Corporation, San Ramon, Calif. (APGVSRC@aol.com) (personal communication, 2004).
  6. K. A. Kraus, R. E. d’Errico, D. Hazen, “The relationship between sky condition and visibility parameters,” in Proceedings of the 8th Symposium on Meteorological Observations and Instrumentation (American Meteorological Society, Boston, Mass., 1993), p. 369.
  7. H. Leelavathi, S. N. Iyer, T. R. Kanakamuthu, G. A. Rao, S. S. Babu, J. P. Pichamuthu, The Automatic Visual Range Assessor, Project Doc. MT 9704 (National Aerospace Laboratories, Bangalore, India, 1997).
  8. J. P. Pichamuthu, The Regime Where the Koschmieder MOR Exceeds the Allard RVR, Project Doc. MT 0106 (National Aerospace Laboratories, Bangalore, India, 2001).

1946

Babu, S. S.

H. Leelavathi, S. N. Iyer, T. R. Kanakamuthu, G. A. Rao, S. S. Babu, J. P. Pichamuthu, The Automatic Visual Range Assessor, Project Doc. MT 9704 (National Aerospace Laboratories, Bangalore, India, 1997).

Blackwell, H. R.

d’Errico, R. E.

K. A. Kraus, R. E. d’Errico, D. Hazen, “The relationship between sky condition and visibility parameters,” in Proceedings of the 8th Symposium on Meteorological Observations and Instrumentation (American Meteorological Society, Boston, Mass., 1993), p. 369.

Ginsburg, A. P.

A. P. Ginsburg, Vision Sciences Research Corporation, San Ramon, Calif. (APGVSRC@aol.com) (personal communication, 2004).

Hazen, D.

K. A. Kraus, R. E. d’Errico, D. Hazen, “The relationship between sky condition and visibility parameters,” in Proceedings of the 8th Symposium on Meteorological Observations and Instrumentation (American Meteorological Society, Boston, Mass., 1993), p. 369.

Iyer, S. N.

H. Leelavathi, S. N. Iyer, T. R. Kanakamuthu, G. A. Rao, S. S. Babu, J. P. Pichamuthu, The Automatic Visual Range Assessor, Project Doc. MT 9704 (National Aerospace Laboratories, Bangalore, India, 1997).

Kanakamuthu, T. R.

H. Leelavathi, S. N. Iyer, T. R. Kanakamuthu, G. A. Rao, S. S. Babu, J. P. Pichamuthu, The Automatic Visual Range Assessor, Project Doc. MT 9704 (National Aerospace Laboratories, Bangalore, India, 1997).

Kraus, K. A.

K. A. Kraus, R. E. d’Errico, D. Hazen, “The relationship between sky condition and visibility parameters,” in Proceedings of the 8th Symposium on Meteorological Observations and Instrumentation (American Meteorological Society, Boston, Mass., 1993), p. 369.

Leelavathi, H.

H. Leelavathi, S. N. Iyer, T. R. Kanakamuthu, G. A. Rao, S. S. Babu, J. P. Pichamuthu, The Automatic Visual Range Assessor, Project Doc. MT 9704 (National Aerospace Laboratories, Bangalore, India, 1997).

Middleton, W. E. K.

W. E. K. Middleton, Vision through the Atmosphere (U. Toronto Press, Toronto, Ontario, Canada, 1952), Chap. 4, p. 62.

Pichamuthu, J. P.

J. P. Pichamuthu, The Regime Where the Koschmieder MOR Exceeds the Allard RVR, Project Doc. MT 0106 (National Aerospace Laboratories, Bangalore, India, 2001).

H. Leelavathi, S. N. Iyer, T. R. Kanakamuthu, G. A. Rao, S. S. Babu, J. P. Pichamuthu, The Automatic Visual Range Assessor, Project Doc. MT 9704 (National Aerospace Laboratories, Bangalore, India, 1997).

Rao, G. A.

H. Leelavathi, S. N. Iyer, T. R. Kanakamuthu, G. A. Rao, S. S. Babu, J. P. Pichamuthu, The Automatic Visual Range Assessor, Project Doc. MT 9704 (National Aerospace Laboratories, Bangalore, India, 1997).

J. Opt. Soc. Am.

Other

Secretariat of the World Meteorological Organization, Guide to Meteorological Instruments and Methods of Observation, 5th ed., WMO document 8 (World Meteorological Organization, Geneva, Switzerland, 1983), Chaps. 10 and 16, pp. 10.1–10.15, 16.4–16.7.

International Civil Aviation Organization, Manual of Runway Visual Range Observing and Reporting Practices, 2nd ed., document 9328-AN/908 (International Civil Aviation Organization, Montreal, Quebec, Canada, 2000).

A. P. Ginsburg, Vision Sciences Research Corporation, San Ramon, Calif. (APGVSRC@aol.com) (personal communication, 2004).

K. A. Kraus, R. E. d’Errico, D. Hazen, “The relationship between sky condition and visibility parameters,” in Proceedings of the 8th Symposium on Meteorological Observations and Instrumentation (American Meteorological Society, Boston, Mass., 1993), p. 369.

H. Leelavathi, S. N. Iyer, T. R. Kanakamuthu, G. A. Rao, S. S. Babu, J. P. Pichamuthu, The Automatic Visual Range Assessor, Project Doc. MT 9704 (National Aerospace Laboratories, Bangalore, India, 1997).

J. P. Pichamuthu, The Regime Where the Koschmieder MOR Exceeds the Allard RVR, Project Doc. MT 0106 (National Aerospace Laboratories, Bangalore, India, 2001).

W. E. K. Middleton, Vision through the Atmosphere (U. Toronto Press, Toronto, Ontario, Canada, 1952), Chap. 4, p. 62.

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Figures (1)

Fig. 1
Fig. 1

Polar plot of brightness distribution (oval shape) superimposed upon a chart of landmark locations. The observer is located at the center of the concentric circles. Inset, dependence of derating factor κ on brightness ratio β for a contrast threshold of 0.05.

Tables (1)

Tables Icon

Table 1 Instrumental, Observed, and Computed (derated) Values of MOR (meters)a

Equations (9)

Equations on this page are rendered with MathJax. Learn more.

B o = B b [ 1 - exp - ( σ R ) ] ,
C = ( B b - B o ) / B b ,
C = exp - ( σ R ) .
R k = 2.996 / σ ~ 3 / σ .
C = ( 1 / β ) exp ( - σ R d ) .
R d = - ( 1 / σ ) ln ( C β ) .
κ = ln ( C β ) / ln ( C ) .
R d = - ( R k / 3 ) ln ( 0.05 β ) ,
κ = - ( 1 / 3 ) ln ( 0.05 β ) .

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