Introduction 



The first four report* in this series, Cromwell (1951 and 1954), Austin (1954) and 

 Stroup (1954), discuss the results of cruises which were planned to provide data leading to a 

 general understanding of the physical and chemical oceanographic features in the nnid-equatorial 

 Pacific (140°W. to I80th meridian). The present report is principadly concerned with cruise 15 

 of the Hugh M. Smith, a cruise planned so as to provide data relating to the tennporal changes 

 along a meridional section across the equatorial circulation. Also included (Appendix I) are the 

 conventional oceanographic data from cruise 16 of the Hugh M. Smith during which a study of 

 the currents was made by means of shallow ajid deep drags. Preliminary results from this 

 cruise have been reported by Cromwell, Montgomery, and Stroup (1954). A more detailed report 

 is being prepared. 



The present report is descriptive. Its primary purpose is to present the data in a 

 form suitable for staff use a-nd for use by other organizations studying the oceanography of the 

 mid-Pacific region. The data are presented in tabular and graphical form, with but brief de- 

 scriptions of the salient features. More complete analytical reports will follow as sufficient 

 data fronn POFI oceanographic cruises in the equatorial region are accumulated. 



The cruise plan for Hugh M. Smith cruise 15 called for a joint cruise with the 

 Cavalieri , a vessel chartered by POFI to explore the feasibility of comnnercial longline fishing 

 in the equatorial area. The Hugh M. Smith was to precede the Cavalieri along 140 W. longitude, 

 determine the current boundaries and advise the Cavalieri where to steirt fishing. However, due 

 to mechanical failure aboard the Cavalieri, she was forced to temporarily abandon the fishing 



and return to Honolulu for repairs, 

 stations as scheduled. 



The Hugh M. Smith continued the program of oceanographic 



The Smith departed Pearl Harbor, Territory of Hawaii, on May 21, 1952, and re- 

 turned on July 1, 1952. The vessel connpleted a total of 60 oceanographic stations comprising 

 four legs along 140 W. longitude between 9 N. and 7 S. latitudes. The station positions for 

 cruise 15 are shown on figure 1. Table 1 summarizes the elapsed tinae for each of the four legs 

 of the cruise. 



Table 1 



Each station consisted of a 13-bottle cast to 500 meters. Sea water Scimples for 

 salinity and phosphate were taJten at each depth sampled. Two 900-foot bathythermograph lower- 

 ings were nnade at each station with additional lowerings at 10-mile intervals between stations. 

 Standard, 200-meter, oblique zooplankton hauls were made at each station using a 1-meter, 

 30xxx silk grit-gauze net. The samples collected by these tows have been processed and the 

 resulting data will be discussed in a forthcoming report. 



