line along southern edge of Kuroshio 



20N :5N 130E UO 130 I6OE 170 180 170W 



500 



000 



Figure 12. — Section of salinity (7.=) versus tliermosteric anomaly (cl t ') along right-hand edge of Kuroshio 

 (upper panel). Section of thermosteric anomaU' versus depth (m) along right-hand edge of Kuroshio (lower 

 panel). (From Masuzav\-a 1972.) 



September 1969 to June 1970. In March 1970 the sea- 

 surface temperature was 2.5°C below the 6 yr average. 

 Above-average temperatures occurred in the winters of 

 1966 and 1969. 



The time variability in the vertical structure at OWS- 

 V as reflected by the smoothed isopleths of salinity and 

 depth versus ct, is shown in Figure 14. Harmonic func- 

 tions were evaluated at the first of each month using 12 

 harmonics for 1968-71 and only the first 3 harmonics for 

 1966 and 1967. The isopleths of salinity and depth are 

 not shown for the time from 1 November 1967 to 1 

 March 1968 due to the large data gap during this time. 

 However, the expected surface salinity and density for 

 day 331 of 1967 and days 1 and 31 of 1968 are plotted and 

 were derived from the harmonic coefficients for the sur- 

 face temperature and salinity at OWS-V (Yong 1971). 



The common feature for all years in the isentropic 



salinity distribution is the constancy of salinity versus a , 

 at depths below the a, 26 level reflecting a constancy of 

 T-S relationships. Note the constancy of the salinity 

 minimum layer at a, 26.8, a feature that was also ap- 

 parent in both the meridional and zonal sections shown 

 in Figures 11 and 12. 



Time variability in the salinity becomes pronounced 

 above the a, 26 level and is associated, in part, with the 

 seasonal change in the surface density. Maximum den- 

 sity at the surface occurs in March or April and 

 minimum density in August or September. In 1970, for 

 example, the maximum surface density was only a little 

 less than a, 26. During the summer when the surface 

 salinity is lower than in winter, a subsurface salinity 

 maximum forms. In winter the highest salinity of 34.6 or 

 34.7%. occurs at the surface. The structure of the subsur- 

 face salinity maximum is variable and may appear as 



16 



