o o 



8. The two absorption dips at 3900 A and 4300 A 



are real and due to actual dips in the solar spectral irradiance 



o 



(see all spectra 19-26 for the intense absorption near 4000 A) , 



9. The structural consistency for the Top of Water 

 spectra is excellent (compare 20, 21 and 22). 



10. The irradiance variation on 2'0--22 ranges over a 

 factor of about 5. This factor com23ares favorably with the 

 Gray Card data and is probably due to changing cloud cover. 

 Therefore, I would accept this variation as being real. 



11. Considering 20 as the best Top of V7ater spectrum 



o 



and comparing with the Gray Card data (25 and 26) at 4500 A 



2 2 



v;e find an irradiance of 8.3 x ].0 [i watts/cm [x for 20 



3 2 



and an average of 3 x 10 [i v^^atts/cin \j. for 25 and 26. Since 



the Gray Card reflectance is known as 0.18 one concludes that 

 the reflectance at the surface of the v;ater is 0.04. Admittedly, 

 many meteorological changes were taking place during this 



o 



time jseriod. Nevertheless, our value of 0.04 at 4500 I\ com.pares 

 favorably with Tyler's value of 0.09 for Crater Lake. 



12. Sfjectra 20--22 are "peakless". Tyler observed the 

 same effect in liis work. 



13. Compare 20 and 25. Very litt].o difference seen 

 betv.-een Gray Card and Top of V7ater in str'nctural detai]. . 



29-6 



