Figure 10.— Dynamic topography (dynamic meters) of the sea surface relative to the 1,000 decibar surface derived from selected stations dur- 

 ing the summer of 1957 (from Kawai 1972). The location of Ocean Weather Station V is denoted by an "X". 



panel) is the constancy of a, of the salinity minimum 

 layer. This layer protrudes southward from the subarc- 

 tic front between lat. 41° and 42°N and is identified 

 with the North Pacific intermediate water (Sverdrup et 

 al. 1942; Reid 1965). During the time of this section, at 

 the latitude of OWS-V, the salinity decreased 

 monotonically from the surface to the depth of the 

 salinity minimum. Farther south, however, shallow 

 salinity maxima occurred. 



The distribution of depth as a function of a, in the sec- 

 tion (Fig. 11, middle panel) reflects the baroclinicity of 

 the zonal flow and embedded eddies. The bottom panel 

 of Figure 11 shows that the principal zonal geostrophic 

 flow occurs between lat. 29° and 35°N. Given the 

 meandering nature of this current (Fig. 10) it is p)ossible 

 that the vertical density structure at OWS-V may be 

 similar to that found within, to the north, or to the south 

 of the current. 



Useful zonal sections have been produced by 

 Masuzawa (1972) from a selection of 18 stations during 

 the summer season on the south side of the Kuroshio 

 and Kuroshio Extension. The distribution of ther- 

 mosteric anomaly versus depth and salinity versus ther- 

 mosteric anomaly are reproduced in Figure 12. [Surfaces 

 of thermosteric anomaly are parallel to surfaces of a, 

 (Montgomery and Wooster 1954).] The middle portion 

 of this section from long. 130° to 170°E runs along 

 approximately lat. 32°N. Note the differences in the dis- 

 tribution of salinity above a, 26.0. East of long. 165°E 

 the highest salinities occur at or near the surface, iden- 

 tifying the North Pacific central water. West of long. 

 160°E a shallow salinity maximum occurs at about o; 

 25. This subtropical water structure with relatively low 



salinity surface water is characteristic of the Kuroshio 

 during summer (Masuzawa 1972). At the longitude of 

 OWS-V, the thermosteric anomaly of 200 cl/f (about a, 

 26) is at 500 m (Fig. 12), but at long. 168°E and at the 

 same latitude as OWS-V a, 26 is near 200 m (Fig. 11). 

 This difference is consistent with the meanders of the 

 current shown in Figure 10. 



Variability and Structure 1966-71 



The seasonal variability of the sea surface 

 temperature and salinity for the 6 years of hydro- 

 graphic observations are shown in the T-S diagrams of 

 Figure 13. Six-year averages provide the reference T-S 

 relationships with temperatures ranging from about 

 16°C in March to 26°C in August and salinities ranging 

 from about 34.73%. in April to 34.437.. in September. 

 Departures from the average pattern during each year 

 appear to be more pronounced in the salinity than in the 

 temperature. For example, from June to December 1966 

 salinities were up to 0.2%. higher. Higher salinities also 

 occurred during spring and early summer of 1968. 

 Salinities were lower than the average during much of 

 the summer and fall of 1969 and again from June to 

 August of 1971. 



A major departure from the average temperature, 

 lasting several months, occurred in 1969-70. 

 Temperatures were 1°C or more below average from 



Figure 11.— Meridional sections, lat. 21° to 42''N, long. 168°E, based 

 on B7 STD stations occupied 3-11 .April 1971. Upper panel: Salinity 

 (7..) vs. (7, values. Middle panel: Depth (m) vs. <r, values. Bottom 

 panel: Dynamic topography (dyn. m.) at the sea surface relative to 

 1,000 decibar surface. 



14 



