Figure F8. Meridional cross section of water masses, characterized by dissolved oxygen concentrations in the tropical East Pacific (Levitus et al., 1993) and Leg 202 site locations. GUC = Gunther Undercurrent, EUC = Equatorial Undercurrent, NPIW = North Pacific Intermediate Water, PCW = Pacific Central Water, PBW = Peru Basin Water. The relatively low oxygen content of water in the Guatemala Basin reflects the water's sources in PCW, relative isolation of water masses within the deep Guatemala Basin, and high organic rain on the Central American margin.