Figure 3. (a) A T-S diagram of Survey II CTD data from the equator to 5 N. (b) A composite temperature section from UOR data in the upper ~100 meters [Aiken and Bellan, 1990] and CTD temperature data below that. Shaded regions on both figures correlate the locations of five water masses in T-S space and physical space. Water with a distinctive signature in T-S (a "cusp", subsurface salinity maximum at temperature ~ 24, labeled "CW") outcrops to the south of the front (revealed by the outcropping of the 26 isotherm), and can be traced northward to 3 N in the CTD data. Other water masses have been called warm surface water ("WSW"), equatorial undercurrent ("EUC"), saddle water ("SW"), and equatorial surface water ("ESW").