REPORT ON OCEANOGRAPHY 85 



Programs: 



Since 1949, a total of 13 oceanographic survey cruises have been 

 conducted, 8 in the equatorial area and 5 in the Hawaiian Island wa- 

 ters. On all cruises, continuous records of surface temperature and 

 data from bathythermograph lowerings at frequent intervals are avail- 

 able. Continuous records of surface temperature and those from less 

 frequent bathythermograph lowerings are available from 13 exploratory 

 fishery cruises in the equatorial region and 19 in the Hawaiian area. 



In general, each oceanographic station consisted of thirteen sam- 

 ples, surface to 1,000 meters. Protected and unprotected reversing ther- 

 mometers were used with the Nansen bottles. Samples were drawn 

 from each depth for chlorinity and phosphate analysis. A 900-foot 

 bathythermograph record and associated meteorological observations 

 were included with each station. 



Current measurements were made by all practicable methods in- 

 cluding the drift of the vessel; drift of the nets or longline when avail- 

 able and by actual measurements of surface currents with the GEK. 

 On one cruise, Cruise 16 of the Smith, shallow and deep drags were 

 used. 1 



Navigational methods include the dead reckoning plot with posi- 

 tions fixed by astronomical sights, Loran and, when practicable, by 

 radar. 



Results: 



Analyses of the data from the cruises in the equatorial region, 

 10°N. to 10°S. latitudes between 140° and 180°W. longitudes, have 

 yielded a better understanding of the equatorial circulation within this 

 area. Summaries of the POFI oceanographic cruises, including discus- 

 sion and tabulation of the station data, are being published in the 

 special scientific reports of the Fish and Wildlife Service, U.S. Depart- 

 ment of the Interior. The first such report, Mid-Pacific Oceanography, 

 January-March 1950, by Townsend Cromwell, was issued in July as 

 SSR No. 54. In addition, Mr. Cromwell has submitted for publication 

 a theoretical consideration of equatorial circulation entitled Circula- 

 tion in a Meridional Plane in the Central Equatorial Pacific. Some of 

 the results of these and other studies presently underway are: 



In general, the circulation pattern consists of the westerly moving 

 North and South Equatorial Currents, with the relatively narrow 

 counter-current between. The northern and southern limits of this 

 counter-current are about 10° and 5°N. respectively. In addition to 

 these surface currents, there is evidence of a sub-surface counter-current 

 centered at the Equator, beneath the South Equatorial Current. Al- 



