A Representative Vertical Ozone Distribution for Atmospheric Transmission Studies Louis Elterman

AFCRL, Bedford, Massachusetts. Received 17 February 1964.

In studies of ultraviolet and infrared transmission of the at­mosphere, the concept of a representative ozone distribution as a function of altitude based on many observations is necessary for carrying out exploratory calculations. This need was met somewhat formally with the publication of the 1957 edition of Handbook of Geophysics,1 which contained a total of eight ozone profiles for various latitudes and seasons. The use of these (at least by meteorologists) was considerable, and the material was reproduced unchanged in the later edition. In 1961, an ozone distribution was proposed by Altshuler2 which was characterized by 0.229 cm N T P total ozone and a maximum concentration at 23 km. This has been designated as a "standard" distribution by Hubbard,3 by Green,4 and by others, either directly or in­directly through the references mentioned.

Since Altshuler's publication, more recent ozone data show that a representative ozone profile differs substantially from this so-called "standard". The Handbook of Geophysics and Space Environment,5 scheduled for publication in late 1964, will provide profiles obtained from a network of twelve ozonesonde stations. I t should be emphasized that an exploratory calculation will be considerably better if the one of these three curves that is best related to latitude and season is used. If only one profile is to be used, it should be the one representing 0.35 cm total ozone. The profiles to be published in the Handbook will be in units of atmospheric altitude and O3 density (microg/m3). The profile is shown here with the units con­verted to altitude (km) and O3 concentration (cm/km).

640 APPLIED OPTICS / Vol. 3, No. 5 / May 1964

Fig. 1. Comparison of ozone concentration profiles.

Furthermore, this distribution has been extended from 40 km upwards to 50 km by utilizing values at these two altitudes de­rived from chemical equilibrium theory6 and interpolating (using semilog paper) between these altitudes.

A comparison of the 1961 and 1964 profiles, other than by the concentrations shown in the figure, can be made by tabulating the atmospheric ozone absorption coefficients at 0.27 μ as a function of altitude. At shorter wavelengths oxygen absorption is con­siderable, and at longer wavelengths the absorptance of O3

diminishes rapidly. If, then, the wavelength 0.27 μ is chosen, the Vigroux absorption coefficient7 is 2.10 X 102 cm - 1 , and the tabulation for each profile is derived from

where

β3 = atmospheric ozone absorption coefficient (km - 1 ) , h= altitude (km),

Av=Vigroux ozone absorption coefficient (cm - 1)) and D3 = ozone equivalent thickness or concentration (cm/km).

The result is shown in Table I. Green4 utilizes a general distribution function (GDF) which

describes the Altshuler profile very satisfactorily for altitudes from 10 km to 50 km. By revising his distribution parameters, the GDF will hold well for altitudes above 18 km for the 0.35-cm profile. From sea level to 18 km, the fit will be loose or unsatis­factory due to the step character of the profile.

The semantics of the topic require a brief comment. The use of the term "standard distribution" for ozone is questionable. Much has been learned concerning ozone distribution in the at­mosphere, but much remains to be learned. Accordingly, less rigid terminology should be used since other distributions will be proposed from time to time. Such terms as representative or generalized distribution seem more apropos.

Acknowledgment is made of the helpful conversations with S. Penn and T. R. Borden of the Meteorological Research

Laboratory, AFCRL, and especially to W. S. Hering who de­veloped the three ozone distribution profiles5 from the many sources available to him.

References 1. Handbook of Geophysics for Air Force Designers (Macmillan,

New York, 1957). 2. T. L. Altshuler, Infrared Transmission and Background

Radiation by Clear Atmospheres, Doc. 61SD199 (General Electric MSVD, Philadelphia, Pa., 1961).

3. E. L. Hubbard, U. of Chicago, Laboratory for Applied Sci­ence, Rept. LAS-TR-199-48, Contract No. SD-71, ARPA (1963).

4. A. E. S. Green, Appl. Opt. 3 , 203 (1964). 5. Handbook of Geophysics and Space Environment (AFCRL,

scheduled for late 1964). 6. J. London, K. Ooyama, and C. Prabhakara, N.Y. University,

Final Report, Contract AF19(604)-5492 (AFCRL, Bedford, Mass., 1962).

7. E. Vigroux, Ann. Phys. 8, 709 (1953).

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