A METHOD FOR THE MEASUREMENT OF 



ATMOSPHERIC OZONE USING THE 



ABSORPTION OF OZONE IN 



THE VISIBLE SPECTRUM 



By OLIVER R. WULF 



U. S. Weather Bureau, California Institute of Technology 



Pasadena, Calif. 



AND 



JAMES E. ZIMMERMAN 



Astrophysical Observatory, Smithsonian Institution 



Table Mountain, Calif. 



1. INTRODUCTION 



By measuring the transmission of the atmosphere for sunlight over 

 a region of the spectrum in which ozone possesses absorption of 

 intensity known from laboratory measurements, the amount of ozone 

 in the vertical path through the atmosphere can be determined. A 

 large variation of the intensity of the absorption with wavelength is 

 in general advantageous. 



The measurement of atmospheric ozone ordinarily utilizes a spectral 

 region in the near ultraviolet. Ozone in the amount existing in the 

 vertical atmospheric path possesses absorption of convenient strength 

 in that region, and the variation of the absorption coefficient with 

 wavelength is relatively large there. 



Ozone also exhibits absorption across the visible spectrum, with a 

 maximum in the yellow-orange that leads to the blue color of this gas 

 in sufficiently large paths. In the atmospheric path the amount of 

 ozone is relatively small and this absorption is weak, making the 

 visible region of the spectrum less suited, so far as this factor is con- 

 cerned, for atmospheric ozone measurement than the ultraviolet region. 

 Also the variation of the absorption coefficient with wavelength is 

 less rapid in the visible. Nevertheless, some effort has been given 

 to the measurement using this absorption, and if the atmospheric 

 scattering and character of the sky in general is also a matter of 

 interest, this region of the spectrum should be a fruitful one for 

 investigation. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 123, NO. 3 



