The yearlong mooring data of salinity and temperature along 156¿E from 8¿N to 5¿S in 1999--2000 obtained from TRITON (TRIangle Trans-Ocean buoy Network) demonstrates that the salinity variation contributed to the variation of surface dynamic height, therefore the geostrophic current. The distribution of the surface dynamic height calculated by observed salinity and temperature reveals a large trough corresponding to the southern edge of the north equatorial countercurrent (NECC), which moved northward from 5¿N to 8¿N in June--September 1999, while the dynamic height calculated by estimated salinity from climatological temperature-salinity relationships and observed temperature does not represent the same movement. This difference is caused by anomalous low salinity waters, which dominate above halocline at 5¿N. This study highlights that, in the Pacific warm pool, the variation of surface geostrophic currents such as the NECC is also affected by salinity variation.