BOTTOM CURRENT MEASUREMENTS IN 

 THE VIRGIN ISLAND PASSAGE 



Robert Gerard and Chris Ceike 

 Lamotit-Doherty Geological Observatory 

 of Columbia University 



ABSTRACT 



Continuous measurement of near-bottom currents were made 

 for a period of 76 hours at the southwestern end of the 

 Virgin Island Passage, using a free-fall, pop-up current- 

 meter package. Observations were made 2 meters above the 

 ocean floor in 1800 meters of water at 17°39.2'N, 65°16'W 

 from 31 August to A September 1970. The current speed 

 record showed a semi-diurnal period with two high and two 

 near-zero nodes every 24 hours. The high current peaks 

 increased in magnitude with time (from 7 to 11 cm/sec) , 

 indicating a longer term periodicity which could not be 

 resolved due to insufficient observation time. The 

 direction of this current also exhibited a semi-diurnal 

 period which appears to have a phase shift in relation to 

 speed. The average direction is towards 168° (SxE) with 

 a turning from SE to S as the average velocity increased 

 with time. 



Another measurement was attempted at the sill of the Anegada 

 Passage to the northeast during the same period, but the 

 current meter was not recovered. 



VII-47 



