Salinity 



The salinity cross sections (fig. 19) show a maximum greater than 35 /oo 

 just below the quasi-homogeneous surface layer at all stations except 22. However, 

 the Hansen bottle spacing was such that this layer was missed in the sampling at a 

 large number of stations, so it was largely constructed by reference to the T-3 

 diagrams of the adjoining stations. The thickness of the layer was greatest in the 

 western section (fig. 19, panel A), where the > 35.0 °/oo band was 100 m. or more 

 in thickness. 



The surface salinity (fig. 20) reflects the extent of the sub-surface 

 maximum by sharp increases in the west and northwest sectors. Over the rest of the 

 area it is almost uniform (34.6 - 34.7 °/oo), except for the area around the middle 

 islands, where a cell of less than 34.6 °/oo occurred, and around stations 10 and 

 31, where it increased sharply. The minimum could only have been caused by runoff 

 from the islands. The maxima were in areas of strong cyclonic motion and could have 

 been caused by divergence. 



Dissolved Oxygen 



The vertical distribution of dissolved oxygen (fig. 21) was typical of 

 the North Pacific at these latitudes. It had a maximuxa of more than 5.0 g/1 just 

 below the level of the well-defined density gradient and a deep minimum of 0.6 - 

 1.0 ml/1 at the 500-800 m. level. The maximum is attributed to contact with the 

 surface at the subtropical convergence during the period when evaporation increased 

 the salinity. Although the minimum is frequently attributed to lack of replenish- 

 ment by horizontal flow, its origin is not completely understood. 



HUGH M. oMITH CfiUISi:; 12 



Cruise 12 of the Hufih M. Smith was made to observe the hydrographic condi- 

 tions in the offshore waters of the Hawaiian Islands during the period when the 

 local skipjack fishery was undergoing its fall decline. The station coverage (fig. 

 22) was similar to cruise 10, but a number of changes were made in the observational 

 program. Dissolved oxygen analyses were omitted and inorganic phosphate analyses 

 were included. The geomagnetic electrokinetograph, which had been installed just 

 before this cruise, was used to make current observations at each station and mid- 

 way between stations. The stations north of Hawaii, 31 to 32 of cruise 10 (fig. llh 

 were omitted to permit further study of the eddj indicated in the vicinity of sta- 

 tion 1 by the G£K data. 



The order and method of presenting the data are the same as for cruises 1 

 and 10. 



General Vjind Pattern 



The winds during the cruise period (table 5) were of about normal force 

 for October, but they were more southeasterly than normal. From October 13 to 26 

 they were part of the circulation around the Eastern I»orth Pacific High, but a 

 greater percentage than normal were from the east and southeast. Therefore, the 

 currents inferred by the 45° cum sole rule are 15° to 55° to the right of the 280°T 

 mean for October. A shift of the currents even further to the right may be in- 

 ferred after October 27, when the wind shifted to the south as a low moved into the 

 area from the west. 



Dynamic Topot-'.raj'hy and Geostrophic Currents 



The dynamic heights (fig. 23) showed less variation than those of cruise 

 10 and consequently the geostrophic currents (fig. 24) were shallower and weaker. 

 Significant velocities of 10 cm/sec (0.2 kt.) or greater were limited to depths of 



13 



