Fig 113 Bissett-Berman (Plessey) water sensor pod with pressure tiousing re- 

 moved Components in cage measure salinity, temperature, sound velocity and 

 depth (WHOII 



Fig. 1 1 4 Water sensor pod logic and recorder components (above and betow). 

 (WHOI) 



down from the sea surface is caught by a 

 cosine collector, passed through a narrow 

 band interference filter with transmission 

 peak matching that of seawater and meas- 

 ured by a photomultiplier. A temperature- 

 compensating circuit reduces the effect of 

 temperature on the photomultipliers. The re- 

 sulting measurements of light flux are re- 

 corded on an open channel of the water 

 sensor pod. 



Data: (A.C. Electronics Model) Under 

 static solar radiation conditions at the sea 

 surface, the change in light flux with depth 

 is a measure of the diffuse extinction coeffi- 

 cient of the seawater. Also, at levels below 

 which natural light can penetrate, the lumi- 

 nescence of passing biological life can be 

 monitored. 



546 



