Introduction 



This report is concerned with cruise 14 of the M/V Hugh M. Smith, the fifth in a 

 series of equatorial oceanographic cruises by the Pacific Oceanic Fishery Investigations of 

 the U. S. Fish and Wildlife Service. _' The cruise was carried out in January and February 

 1952 in conjunction with longline tuna fishing in the same area on cruise 11 of the M/V John 

 R. Manning; the results of the fishing have been described by Murphy and Shomura (195 3). 

 The purpose of these simultaneous operations was to help relate the occurrence of tunas to 

 the oceanography of the upper layers in the equatorial Pacific between 155 W. and 180 

 longitude. 



Measurements of surface and subsurface temperature, salinity, and inorganic 

 phosphate as well as plankton collections were made during Smith cruise 14. The purpose 

 of this report is to present the tabulated station data and various vertical sections, with 

 minimum analysis of results. There are, in addition, brief descriptions of one of the smaller 

 features of the area. The results of the plankton collections will appear in later reports. 



Vessel, Equipment, and Procedures 



The shipboard equipment was essentially as described by Cromwell (1951), except 

 that the hydrographic winch and work platform were raised to a safer and more workable loca- 

 tion on the boat deck, about 6 meters above the sea surface (see frontispiece). The main-deck 

 laboratories were also redesigned for greater convenience. The methods of collection and 

 processing of the raw data have been described in detail (Cromwell 1951, 1954). 



The treatment of the observed data from Smith cruise 14 leading to their ultimate 

 presentation as interpolated data and vertical sections differs somewhat from the previous 

 cruises. Smith cruises 5 and 8 (Cromwell 1954) and 11 (Austin 1954) were presented using 

 modifications of the methods proposed by Montgomery in his evaluation of a Smith cruise 2 

 section (Montgomery 1954). The procedures used in the analysis of Smith cruise 14 are, in 

 effect, an extension of Montgomery's method, embodying, in addition to the methods he em- 

 ployed, several further details suggested in his paper. An outline of the method of analysis 

 will be given here; reference to the reports above (especially Montgomery 1954) should be 

 made for detailed discussion and theoretical consideration. 



The basic representation of each oceanographic station was made on a graph embody- 

 ing a temperature scale vs. scales of depth, salinity, and phosphate phosphorous, with lines of 

 constant sigma-t corresponding to the temperature and salinity arguments also included on the 

 graph (fig. 1). Temperature-depth curves for each station were first drawn, passing through 

 the values obtained from the reversing thermometers but utilizing the shape of the station 

 bathythermograph (BT) trace to define detail in the upper 270 meters. Temperature-salinity 

 and temperature-phosphate curves (station "characteristic curves") were then drawn. Values 

 from adjacent stations, and in many cases from stations two or three removed on the same 

 longitude, assisted in construction of the curves between observed points; this was readily 

 accomplished by superposing the station graphs on a light table during the drawing. The neces- 

 sity for this procedure is evident in an examination of the vertical sections (see below). The 

 depths sampled by the Nansen bottles (entered as dots on the sections) necessarily often miss 

 some of the major features of the distributions, especially in the region of the thermocline, but 

 by utilizing adjacent-station values the continuity of these features is not destroyed. The varia- 

 tions in these characteristic curves with latitude were made as regular as possible, and, so far 

 as the observed data permitted, maxima and minima were located on the same respective values 

 of sigma-t from station to station. 



1/ Certain results of the previous cruises in this series appear in reports by Cromwell (1951, 

 ~ 1953, 1954), Austin (1954), and Montgomery ( 1954). 



