The thermohaline structure at 4 °S, 156 °E was analyzed based on CTD data acquired during theTOGA COARE Intensive Observing Period(IOP) from November,1992 to February,1993. The ocean re-sponses during two Madden-Julian Oscillation(MJO)events were preliminarily studied based onmeteorological field observation.The main water masses at the observation point were Tropical SurfaceWater, Southern Subtropical Lower Water and Southern Intermediate Water from surface downward. Therewas good correlation of sea surface temperature with the wind field,and of the surface salinity with windspeed and rainfalls. Both of the two surface variables were also modulated by upwelling caused by west-erly winds at the observation point. The isohaline layer was not always shallower than the isothermal lay-er in this observation and could be considered as the lower limit of the diurnal variation of theisothermal layers in most cases. The existence of large variations of the maximum salinity core is sug-gested to be related to t The thermohaline structure at 4 ° S, 156 ° E was analyzed based on CTD data acquired during the TOGA COARE Intensive Observing Period (IOP) from November, 1992 to February, 1993. The ocean re-sponses during two Madden-Julian Oscillation (MJO) events were preliminarily studied based onmeteorological field observation.The main water masses at the observation point were Tropical Surface Water, Southern Subtropical Lower Water and Southern Intermediate Water from surface downward. Therewas good correlation of sea surface temperature with the wind field, and of the surface salinity with windspeed and rainfalls. Both of the two surface variables were also modulated by upwelling caused by west-erly winds at the observation point. The isohaline layer was not always shallower than the isothermal lay-er in this observation and could be be considered as the lower limit of the diurnal variation of theisothermal layers in most cases. The existence of large variations of the maximum salinity core is sug-gested to be related to t