N. 

 26' 



156° 154° 



V2C>"^"' 







^■-.. 



Figure 1. --Cruise track and station pattern 

 of the Trade Wind Zone Oceanography Pilot 

 Study. Open dots represent oceanographic 

 stations, crosses represent bathythermograph 

 stations. 



The general distribution of temperature and salinity in the 

 trade wind zone region of the central North Pacific based on 

 historic data is well known. (See, for example, recent publi- 

 cations by Barkley, 1968; Reid, 1965; and Tsuchiya, 1968.) 

 The sections of this circular, however, provide, in addition to 

 more detail, the month-to-month changes in the distribution of 

 temperature, salinity, and water masses that occurred from 

 February 1964 to June 1965. Although predictions for any given 

 month cannot be made, the sections show the month-to-month 

 variability and limits of occurrence that can be expected of the 

 properties presented. 



Not all of those who may use this circular are familiar with 

 the central North Pacific or are specialists in oceanography. 

 For this reason some basic features of the vertical tempera- 

 ture and salinity distributions are described below and pos- 

 sible applications are indicated. 



Finally, since the oxygen concentration was not determined 

 regularly during the TWZO cruises, I show how the gross dis- 

 tribution of the dissolved oxygen concentration can be inferred 

 from salinity sections. 



DESCRIPTION OF SECTIONS 



The temperature and salinity sections are presented in sets 

 of four each per cruise and are identified by cruise number, 

 month, and year when the cruise began. The temperature dis- 

 tribution in ° C. from the surface to 240 m. is based on bathy- 

 thermograph observations made at 30-nautical mile intervals. 

 The salinity distribution in parts per thousand (grams of salt 

 per kilogram of water) from the surface to 600 m. is based on 

 oceanographic stations occupied at 90-nautical m ile intervals 

 (see fig. 1). At these stations samples were obtained at 25-m. 



