From January to June 1979 the R. V. Meteor surveyed the central equatorial Atlantic on a line along 22W from 2S to 3N. By means of CTD and horizontal deflection measurements of a towed undulating instrument, the "Delphin," a time series of the horizontal location of the velocity core of the Equatorial Undercurrent and its related salinity maximum could be obtained. The time interval of observations between the 11 "Delphin" sections ranged from 5 to 30 days. In the mean the salinity maximum is located 30 km south of the velocity maximum. The separation distance depends on the meridional location of the cores and is highest when the cores are farthest to the north. The separation can be explained by asymmetric vertical erosion of the salinity core. The erosion is stronger at the northern flank. This is due to the presence of a tongue of low salinity water which originates by modification of South Equatorial Current water with Gulf of Guinea water.