2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I23 



Craig has reviewed the subject of atmospheric ozone in a recent 

 monograph/ Concerning the visible region of the spectrum in par- 

 ticular, we wish to mention here the work of Cabannes and Dufay ^ 

 and of Fowle ^ having to do with data obtained in the work of the 

 Smithsonian Astrophysical Observatory, as does the present paper ; 

 of Gauzit * who used a method of visual spectrophotometry ; and of 

 Duninowski ^ who employed an apparatus that recorded the spectral 

 distribution of the intensity of solar radiation in a manner similar to 

 that in the regular work of the Smithsonian Astrophysical Observa- 

 tory. More recently Tien Kiu ** made a detailed study of atmospheric 

 optical density using Smithsonian data from the station at Montezuma, 

 Chile. This work includes a graphical evaluation of ozone. 



A convenient means of adequately measuring atmospheric ozone 

 using the visible region of the spectrum would make possible a helpful 

 comparison with daily measurements employing the ultraviolet region. 

 Moreover, such work in the visible region is, in certain respects, 

 somewhat less demanding instrumentally than that in the ultraviolet, 

 and it seems possible that a procedure, reliable though somewhat less 

 precise than that commonly employed in the ultraviolet, might be 

 developed for the visible. 



2. PURPOSE OF THE PRESENT WORK 



The atmospheric transmission coefficients, obtained in the work 

 of the Smithsonian Astrophysical Observatory on days of especially 

 clear skies when the "long method" of observing is employed in the 

 determination of the solar constant, offer an unusual opportunity to 

 determine the vertical-path ozone using the visible region of the spec- 

 trum. It is on these transmission coefficients at appropriately chosen 

 places in the spectrum that most of the relatively small amount of 

 earlier work in this spectral region has been based (see, however, 

 footnotes 4 and 5 ) . The present investigation attempts to put the use 

 of these transmission coefficients for the determination of ozone on 

 any one day on as accurate a basis as practicable and to provide a rapid 

 computational method for making the determination. 



1 Craig, R. A., Amer. Meteorol. Soc, Meteorological Monographs, vol. I, 

 No. 2, 1950. 



~ Cabannes, J., and Dufay, J., Journ. Phys. et Rad., ser. 6, vol. 7, p. 257, 

 1926; ibid., ser. 6, vol. 8, p. 353, 1927. 



3 Fowle, F. E., Smithsonian Misc. Coll., vol. 81, No. 11, 1929. 



* Gauzit, J., Thesis, Paris, 1935. 



5 Duninowski, A. I., Thesis, Montpellier, 1932. 



6 Tien Kiu, Journ. Phys. et Rad., ser. 7, vol. 9, p. 297, 1938. 



