SOME OBSERVATIONS ON WATER COLOR 

 ON THE CONTINENTAL SHELF 



R. W. Austin 



NOTE: The original presentation relied heavily upon colored photographs 

 obtained from Gemini and Apollo space missions and by the 

 author from surface vessels. The following is considerably modi- 

 fied and abbreviated as it is not feasible to use color printing in 

 these proceedings. 



The author had the opportunity to make observations and measure- 

 ments from a surface vessel along the very extensive continental shelf 

 bordering the eastern coast of Asia from the Yellow Sea to the South China 

 Sea. Subjective determinations were made of water color and physical 

 measurements were made of the attenuation of the natural (diffuse) light 

 field in the water and of the reflectance of the water (ratio of the upwell- 

 ing to the downwelling illuminances). Information was obtained at over 

 50 locations. 



Space photographs show marked local variations in water color, 

 and presumably other optical properties, over small horizontal distances 

 in the areas seaward from the mouths of rivers for many miles. Some of 

 these rivers carry large quantities of silts having strong colorations. The 

 measurements made from the surface vessel many miles from the coast 

 confirmed the existence of many areas having higher than usual water re- 

 flectance values and concomitant high values of attenuation. 



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