Salinity variability in the equatorial Pacific Ocean during the 1993-98 period

The salinity variability during the 1993-98 period in the equatorial Pacific Ocean is estimated by an indirect method based on statistical modes which are fitted to the TAO temperature profiles and the TTP sea level observations. The maximum variability in salinity occurs primarily in the fresh warm pool of the western Pacific. The nature of the variability is consistent with different mechanisms recently proposed. From mid-95 to the end of 1996, positive anomalies of salinity in the upper layers near the eastern edge of the warm pool lead to a negative steric height anomaly which represent up to 30-40% of the thermal counterpart. As a consequence, the heat storage is significantly greater than the one would have inferred from observed sea level fluctuations only. The potential impact of the salinity field during the 1997-98 El Nino event is also discussed.