UPPER OCEAN THERMOHALINE FIELDS NEAR 2-DEGREES-S, 156-DEGREES-E, DURING THE TROPICAL OCEAN GLOBAL ATMOSPHERE COUPLED OCEAN-ATMOSPHERE RESPONSE EXPERIMENT, NOVEMBER 1992 TO FEBRUARY 1993

Zonal and meridional Seasoar sections centered at 1 degrees 50'S, 156 degrees 06'E were repeated >30 times in three 20-day periods between N ovember 13, 1992, and February 15, 1993. Both sections were 130 km lon g, and sampling depth was 0-280 m, with a vertical resolution of simil ar to 2 dbar (2 x 10(4) Pa) and a horizontal resolution of similar to 3 km. The observed fields are complex and variable and are summarized graphically in several forms. Characteristics of the near-surface laye r varied with the local winds which were variable and weak (< 6 m s(-1 )) during the first 20-day period, strong and westerly (> 10 m s(-1)) during much of the second, and moderate and westerly (4-10 m s(-1)) du ring most of the third. Near-surface temperatures were warmest (up to 30 degrees C) during the first period and coldest (often < 29 degrees C) during the second. Thermal stratification in the near-surface layer was strong under weak winds and weak under strong and moderate winds. Except during and after heavy rainfall, salinity stratification iii t he near-surface layer was generally weak. Surface salinity generally d ecreased toward the north. The depth of the surface isopycnal layer wa s often but not always limited by salinity stratification; the surface isohaline layer was shallower than the top of the thermocline through out. Strong lateral temperature and salinity gradients occurred on a f ew occasions, Increased wind stress was associated with lateral homoge nization as well as vertical mixing, Structure and water properties of the thermocline also varied between cruises and within each cruise. T he upper thermocline was shallowest in late January after prolonged ea sterly winds. Isotherms in the upper and midthermocline (20 degrees-25 degrees C) sloped generally upward to the north, while those in the l ower thermocline (12 degrees-14 degrees C) sloped down to envelop the core of the Equatorial Undercurrent, which shoaled (from 225 to 160 m) and warmed (from 15 degrees to 20 degrees C) between the first and la st survey periods. Mesoscale and fine-scale water mass features were u sually recognizable in sections less than a few days apart and migrate d eastward sit about 0.3 m s(-1). There is a remarkably high degree of nonstationarity in these thermohaline fields from the Warm Pool of th e western Pacific Ocean.