Effects of correcting salinity with altimeter measurements in an equatorial Pacific ocean model

In this paper, we study the consequences of making salinity corrections in a tropical Pacific ocean model run for the period 1993–1997. Salinity and temperature corrections are obtained by assimilating temperature profile data and TOPEX/Poseidon sea level observations in the ocean general circulation model of the National Centers for Environmental Prediction (NCEP). The results are compared to two model runs in which no salinity corrections have been made, one using only temperature data and the other using both temperature and sea level data. The salinity correction sharpens the salinity front at the eastern edge of the western Pacific fresh pool, leading to improved patterns of salinity variability in the model. In addition, the salinity correction allows the model to follow both the temperature and the sea level more closely and estimates the heat content more accurately compared to the case when only temperature is corrected. In the western Pacific, the zonal pressure gradient resulting from the combined temperature and salinity corrections causes an acceleration of the Equatorial Under Current (EUC) that differs from the case when correcting temperature only. In the eastern Pacific, zonal current changes are similar for both runs in which sea level has been assimilated, and are directly related to local changes in surface pressure. We do not observe a remote effect of the salinity corrections on the zonal current structure in the eastern Pacific.