The oceanographic conditions along 134 degree E from 12 degree N to 30 degree N in September, 2003 and 2009

The CTD observations were carried out along 134 degree E from 12 degree N to 30 degree N in the northwestern part of the North Pacific in September's of 2003 and 2009. The surface layers warmer than 27.5 degree C were observed from 12 degree N to 27 degree N in 2003 and observed from 12 degree N to 22 degree N in 2009. The present paper aims to comparing the September's hydrographic conditions for the two years. The subtropical Mode Water occupied the subsurface layer between 200m and 400m depths in the region between 18 degree N and 24 degree N for 2003, while in that between 18 degree N and 26 degree N for 2009. The North Equatorial Current, which is identified by the downward slope of isotherms toward the south, was observed north of 17 degree N in 2003 while north of 15 degree N in 2009. The saline water higher than 34.8 psu occupied the subsurface layer between 100 m and 250 m depths in the almost whole section in 2003, whereas only in the region north of 21 degree N in 2009. The halocline below the subsurface saline water, was identified between 34.5 psu and 34.7 psu in the entire sections for both the years. The intermediate water fresher than 34.2 psu occupied within the depths from 550 m to 850 m in the region between 18 degree N and 27 degree N in 2003, but the depths from 550 m to 750 m in the region between 19 degree N and 27 degree N in 2009.