NO. 3 MEASUREMENT OF OZONE — WULF AND ZIMMERMAN I3 



where each one of these three quantities is the result of the summation 

 of seven terms arising in the multiplication. 



The final results are thus given in (i6). It is instructive to sub- 

 stitute these values of x, 8, and C into equation (i) and compute the 

 optical densities for each of the seven spectrum places. These may 

 be compared with the measured optical densities. This gives an idea 

 of how satisfactorily the measured transmission coefficients at the 

 seven spectrum places have been represented by (i). The calculated 

 optical densities for this day have the values given in table 4. Com- 



Table 4 



Place 19 20 22 24 26 28 30 



Computed optical 

 densities 0.01695 0.02157 0.03897 0.04779 0.05234 0.05970 0.07174 



parison of these values with the values of table 3 shows that the 

 average difference between the measured and calculated values is 

 roughly 0.0005. I^i the transmission coefficients this means a differ- 

 ence of about one unit in the third figure, which indicates that for this 

 day the measured values have been well represented by equation ( i ) . 

 In this respect this particular day is somewhat better than average. 



In the above illustrative calculations no correction was made for 

 water absorption. The precipitable water for this day was, however, 

 0.628 cm, for which (see section 4) we believe a correction at Place 24 

 is warranted. For this water value the term r^-pptHaO is 0.00057. 

 Subtracting this from the value 0.02009 for Place 24 in the matrix L 

 of (15) yields 0.01952 as the value corrected for water absorption. 

 Inserting this in place of the value 0.02009 in L and solving otherwise 

 as before gives 



.^ = 0.250 



8 = 0.0147 (17) 



^ = 0.0145 



as compared with the values given in (16) which were obtained before 

 the water correction. Recomputing the optical densities, using (17) 

 instead of ( 16) , we get the values given in table 5. 



Table 5 



Place 19 20 22 24 26 28 30 



Computed optical 

 densities 0.01701 0.02158 0.03876 0.04811 0.05222 0.05968 0.07176 



As to the accuracy of the ozone determination, this can be better 

 estimated after an intensive study of a series of measurements have 



