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Applied Optics

Applied Optics


  • Vol. 41, Iss. 12 — Apr. 20, 2002
  • pp: 2292–2298

Refractive Index of Air: 3. The Roles of CO2, H2O, and Refractivity Virials

Philip E. Ciddor  »View Author Affiliations

Applied Optics, Vol. 41, Issue 12, pp. 2292-2298 (2002)

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The author’s recent studies of the refractive index of air are extended, and several assumptions made therein are further examined. It is shown that the alternative dispersion equations for CO<sub>2</sub>, which are due to Edlen [Metrologia <b>2,</b> 71 (1966)] and Old <i>et al</i>. [J. Opt. Soc. Am. <b>61,</b> 89 (1971)] result in differences of less than 2 × 10<sup>−9</sup> in the phase refractive index and less than 3 × 10<sup>−9</sup> in the group refractive index for current and predicted concentrations of CO<sub>2</sub>. However, because the dispersion equation given by Old <i>et al</i>. is consistent with experimental data in the near infrared, it is preferable to the equation used by Edlen, which is valid only in the ultraviolet and the visible. The classical measurement by Barrell and Sears [Philos. Trans. R. Soc. London Ser. A <b>238,</b> 1 (1939)] on the refractivity of moist air is shown to have some procedural errors in addition to the one discussed by Birch and Downs [Metrologia <b>30,</b> 155 (1993)]. It is shown that for normal atmospheric conditions the higher refractivity virial coefficients related to the Lorentz-Lorenz relation are adequately incorporated into the empirically determined first refractivity virial. As a guide to users the practical limits to the calculation of the refractive index of the atmosphere that result from the uncertainties in the measurement of the various atmospheric parameters are summarized.

© 2002 Optical Society of America

OCIS Codes
(010.1290) Atmospheric and oceanic optics : Atmospheric optics
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.3940) Instrumentation, measurement, and metrology : Metrology

Philip E. Ciddor, "Refractive Index of Air: 3. The Roles of CO2, H2O, and Refractivity Virials," Appl. Opt. 41, 2292-2298 (2002)

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  1. P. E. Ciddor, “Refractive index of air: new equations for the visible and the near infrared,” Appl. Opt. 35, 1566–1573 (1996).
  2. P. E. Ciddor and R. J. Hill, “Refractive index of air: 2. Group index,” Appl. Opt. 38, 1663–1667 (1999).
  3. B. Edlen, “The refractive index of air,” Metrologia 2, 71–80 (1966).
  4. C. Cuthbertson and M. Cuthbertson, “On the refraction and dispersion of carbon dioxide, carbon monoxide, and methane,” Proc. R. Soc. London A 97, 152–159 (1920).
  5. J. G. Old, K. L. Gentili, and E. R. Peck, “Dispersion of carbon dioxide,” J. Opt. Soc. Am. 61, 89–90 (1971).
  6. A. C. Simmons, “The refractive index and Lorentz-Lorenz functions of propane, nitrogen and carbon-dioxide in the spectral range 15803–22002 cm−1 and at 944 cm−1,” Opt. Commun. 25, 211–214 (1978).
  7. P. Giacomo, “Equation for the determination of the density of moist air (1981),” Metrologia 18, 33–40 (1982).
  8. R. S. Davis, “Equation for the determination of the density of moist air (1981/1991),” Metrologia 29, 67–70 (1992).
  9. H. Barrell and J. E. Sears, “The refraction and dispersion of air for the visible spectrum,” Philos. Trans. R. Soc. London Ser. A 238, 1–64 (1939).
  10. J. C. Owens, “Optical refractive index of air,” Appl. Opt. 6, 51–59 (1967).
  11. K. P. Birch and M. J. Downs, “An updated Edlen equation for the refractive index of air,” Metrologia 30, 155–162 (1993).
  12. K. P. Birch and M. J. Downs, “Correction to the updated Edlen equation for the refractive index of air,” Metrologia 31, 315–316 (1994).
  13. R. J. Hill, “Refractive index of atmospheric gases,” in The Upper Atmosphere, W. Diemenger, G. Hartmann, and R. Leitinger, eds. (Springer, Berlin, 1995), pp. 261–270.
  14. K. P. Birch and M. J. Downs, “The precise determination of the refractive index of air,” Rep. MOM90, (National Physical Laboratory, Teddington, Middlesex, TW11 0LW, U.K., 1988), pp. 1–35.
  15. K. P. Birch, 36 Fircroft Road, Chessington, Surrey, KT9 1RW, U.K. (personal communication, 2000).
  16. H. J. Achtermann, G. Magnus, and T. K. Bose, “Refractivity virial coefficients of gaseous CH4, C2H4, C2H6, CO2, SF6, H2, N2, He, and Ar,” J. Chem. Phys. 94, 5669–5684 (1991).
  17. G. Montixi, R. Coulon, and R. Occelli, “Coefficients du viriel de la réfractivité de l’azote à 25 °C,” Can. J. Phys. 61, 473–479 (1983).
  18. R. C. Burns, C. Graham, and A. R. M. Weeler, “Direct measurement and calculation of the second refractivity virial coefficients of gases,” Mol. Phys. 59, 41–64 (1986).
  19. See, for example, R. Carmichael, “A table of the standard atmosphere to 65,000 feet,” (Public Domain Aeronautical Software, Santa Cruz, Calif., 12 June 2001), http://www.pdas.com/m1.htm.
  20. I. G. Enting, T. M. L. Wigley, and M. Heimann, “Future emissions and concentrations of carbon dioxide: key ocean/atmosphere/land analyses,” Tech. Paper 31 (CSIRO Division of Atmospheric Research, Melbourne, Australia, 1994), p. 120. On-line edition available at http://www.dar.csiro.au, (search for publications\enting_2001a0.pdf).
  21. R. J. Hill, “Infrared refractive index software, IR_N, 2000,” Environmental Research Laboratories, NOAA, 325 Broadway, Boulder, Colorado 80303–3328 (personal communication, May 2000). (A limited number of copies of this software are available on compact disk from P. E. Ciddor or from J.M.Rueger@unsw.edu.au).
  22. Association Internationale de Géodesie, Handbook of Geodesy (on-line edition, 2000),” http://www.gfy.ku.dk/~iag/HB2000/part2/iag_res.htm.
  23. J. A. Stone and J. H. Zimmerman, “Index of refraction of air,” (National Institute of Science and Technology, Gaithersburg, Maryland, 12 June 2001), http://patapsco.nist.gov/mel/div821.
  24. M. J. Kenny, C. J. Walsh, A. J. Leistner, K. Fen, W. J. Giardini, L. S. Wielunski, and B. R. Ward, “Determination of the Avogadro constant from precision density measurements on a silicon sphere,” in Proceedings of the Conference on Precision Electromagnetic Measurements, J. Hunter and L. Johnson, eds. (Institute of Electrical and Electronic Engineers, Piscataway, N.J., 2000), pp. 184–185.

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