A PACIFIC HYDROGRAPHIC SECTION AT 88-DEGREES-W - WATER-PROPERTY DISTRIBUTION

Full-depth conductivity-temperature-depth (CTD)/hydrographic measureme nts with high horizontal and vertical resolution were made in February -April 1993 along a line lying at a nominal longitude of 88 degrees W and extending from southern Chile (54 degrees S) to Guatemala (14 degr ees N). It crossed five major deep basins (Southeast Pacific, Chile, P eru, Panama, and Guatemala basins) east of the East Pacific Rise. Vert ical sections of potential temperature, salinity, potential density, o xygen, silica, phosphate, nitrate, and nitrite are presented to illust rate the structure of the entire water column. Some features of intere st found in the sections are described, and an attempt is made to inte rpret them in terms of the isopycnal property distributions associated with the large-scale ocean circulation. These features include: vario us near-surface waters observed in the tropical and subtropical region s and the fronts that mark the boundaries of these waters; the possibl e importance of salt fingering to the downward salt transfer from the high-salinity subtropical water; a shallow thermostad (pycnostad) deve loped at 16 degrees-18.5 degrees C in the subtropical water; low-salin ity surface water in the subantarctic zone west of southern Chile; lar ge domains of extremely low oxygen in the subpycnocline layer on both sides of the equator and a secondary nitrite maximum associated with a nitrate minimum in these low-oxygen domains; high-salinity, low-oxyge n, high-nutrient subpycnocline water that is carried poleward along th e eastern boundary by the Peru-Chile Undercurrent; the Subantarctic Mo de and Antarctic Intermediate waters; middepth isopycnal property extr ema observed at the crest of the Sala y Gomez Ridge; influences of the North Pacific and the North Atlantic upon deep waters along the secti on; and the characteristics and sources of the bottom waters in the fi ve deep basins along the section.