OCEAN CURRENTS OVER PLANTAGENET BANK, BERMUDA 



INTRODUCTION 



The U. S. Navy Etydrographic Office*is currently engaged in a 

 comprehensive environmental research program at the Navy's ARGUS ISLAND 

 tower on Plantagenet Bank near Bermuda (Figure 1). This Texas-Tower- 

 type structure (Figiire 2) was constructed during the summer of 1959 in 

 support of underwater acoustics research activities under the direction 

 of the Office of Naval Research. Through cooperation of the Office of 

 Naval Research, arrangements have been made for utilization of the tower 

 by the Hydrographic Office as an oceanographic research platform. This 

 research effort is associated with the development of the Antisubmarine 

 Warfare Environmental Prediction System (ASVEPS) and is an outgrowth of 

 experience gained by the I^drographic Office at Texas Towers 2 and k 

 (Carlson and collaborators, 1956; Gaxa, 1961). 



Prior to the initiation of oceanographic research at ARGUS ISLAND, 

 it was necessary to consider the extent to which environmental studies 

 on Plantagenet Bank would be descriptive of adjacent ocean processes. 

 Such considerations must involve the question of distribution of oceano- 

 graphic properties over the Bank as well as the influence of the Bank on 

 currents which influence these properties. Thus, a current study in 

 conjunction with a survey of the distribution of the oceanographic vari- 

 ables over Plantagenet Bank was considered of primary importance in de- 

 termining the significance of future studies at ARGUS ISLAND. 



Plantagenet Bank is situated atop a seamount which protrudes ab- 

 ruptly from the deep ocean floor approximately 20 miles southwest of 

 Bermuda. The area of the Bank is approximately 15 square miles and is 

 characterized by a relatively uniform 30-fathom depth. The bottom 

 plunges sharply off the edge of the Bank to great depths. 



The circxilation over the Bank has recently been a subject of spec- 

 ulation based on a limited number of observations. Unpublished inves- 

 tigations by the Columbia University Geophysical Field Station, St. 

 Davids, Bermuda have indicated that these currents are quite variable, 

 with wind and tidal influences being difficult to recognize. Rfcent 

 studies by the Woods Hole Oceanographic Institution (Bruce, I961), how- 

 ever, have largely clarified the nature of the October circulation im- 

 mediately southwest of the Bank. 



Prior to undertaking detailed environmental studies at ARGUS 

 ISLAND, supplementary observations of the circulation over the Bank 

 were considered necessary. Current data contained in this report con- 

 stitute a portion of the preliminary efforts to satisfy this require- 

 ment. These data were obtained through the utilization of the USS 

 PREVAIL (AGS-20) between 1 and 15 August I961. 



* Redesignated U. S. Naval Oceanographic Office 10 July I962 



