Rudol ph Hoi 1 man 



Dept. of Meteorology and Oceanography 



New York University 



Bronx, N. Y. 



Over the oast years we have made a study of the albedo of the 

 sea surface, that is, the ratio of the uoward radiant flux to the 

 downward radiant flux, over the rather broad soectral band of 

 approximately 0.35u to 2.5u. The instrumentation consisted of two 

 Epnlv pyranometers , a oyrhel iometer , and a photocell. The two 

 pyranometers were mounted back-to-back on a gimbal mounting affixed 

 to a long boom that was extended over the bow of the research vessel. 

 The upright pyranometer sensed the total downward radiant flux 

 (irradiance) or global radiation and the inverted ovranometer sensed 

 the UDward radiant flux from the sea surface. The ratio of these 

 two irradiances is defined as the albedo. The pyrhel iometer measured 

 the direct solar radiation so that the difference between the global 

 and the direct radiation yields a measure of the diffuse sky radiation. 

 The calibrated photocell was mounted on a float and provided a measure 

 of the unv/ard radiant flux due to scattering within the water. These 

 measurements were largely carried out over the waters of Eastern Long 

 I si and Sound . 



The results of these measurements show that the backscattered 

 light contributes significantly (25 to 50^) to the albedo. We know 

 that the albedo depends upon the solar altitude but vie found the albedo 

 also depends upon the state or condition of the atmosnhere, that is, 

 cloud conditions, turbidity, etc. An index of the state of the atmosohere 



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