1.2 Observations 



In 1961, the Coast and Geodetic Survey of the United States Department of Commerce 

 began field work on a survey of that part of the North Pacific Ocean between the Hawaiian 

 Islands on the south, the Aleutian Islands on the north, and (approximately) the 158° W 

 and 180° meridians on the east and west, respectively. Oceanographic stations in this 

 program included observations of temperature by reversing thermometers, salinity by 

 salinometer, and dissolved oxygen by Winkler titration (table 1 and fig. 1). Only those 

 stations deeper than 2,000 meters (fig. 2) were useful for the present study. The field 

 observations are summarized graphically in figures 3 through 17. 



Table 1. — Recent Coast and Geodetic Survey observations in the central North Pacific 



Ocean 



Values for the variables at standard depths and computed values of sigma-f, the 

 specific volume anomaly, the geopotential anomaly, and the potential energy anomaly 

 (Fofonoff, 1962), were determined by means of an interpolation and computation program 

 prepared by the Applied Mathematics staff of the Department of Oceanography. University 

 of Washington. The computations were made on the University's IBM 709 computer. 

 The 1961 and 1962 observations were also submitted to the National Oceanographic Data 

 Center, where values for standard depths were again calculated. The values reported 

 by the National Oceanographic Data Center disagree slightly with those from the Uni- 

 versity because of minor variations in the two interpolation and computation programs. 



1.3 Description of the Area 



The observations listed above are of considerable interest in supporting recent de- 

 criptions of the fields of oceanographic variables in the central North Pacific Ocean. 

 Since 1955, co-operative efforts such as those summarized by the NORPAC Committee 

 (1960a, b), observations resulting from International Geophysical Year cruises, programs 

 of the International North Pacific Fisheries Commission and of the Bureau of Commercial 

 Fisheries in connection with its Pacific Oceanic Fisheries Investigations, have provided 

 a basis for detailed descriptions of the area by previous investigators. The present 

 investigation confirms these descriptions of temperature, salinity and oxygen distributions 

 (figs. 3 to 17 inclusive), and amplifies certain details. However, the primary purpose of 

 this investigation is to describe the circulation and characteristics of the deep water. 



Most oceanographic descriptions of this area treat the upper 1,000 meters because 

 that stratum includes the more striking parts of the structure, and relatively few data 

 are available from greater depths. Hence, most descriptions of the circulation deal with 

 surface velocities or are limited to velocities and transports above 1,000 meters. Reid 

 (1961) described the surface geostrophic flow for the Pacific Ocean. His calculations 

 were based on a level of no net motion at 1.000 decibars. The NORPAC Atlas (1960a) 

 covers in greater detail the geostrophic flow in the North Pacific Ocean. Permanent 

 features of the surface flow in the central north Pacific Ocean are: the Alaskan Stream and 



