On the Wind-Driven Cross-Equatorial Flow in the Atlantic Ocean

Abstract

The zonally-integrated curl of the wind stress across the equatorial Atlantic Ocean results in a southward transport of 10 ? 106 m3 s?1 of water into the South Atlantic, which must be returned in a western boundary current Historical hydrographic and wind data have been used together with a simple steady model to calculate the vertical and horizontal structure of the southward Sverdrup transport. In contrast to the Pacific Ocean, the meridional currents are southward over most of the equatorial Atlantic with strongest flow in the central Atlantic near the surface; the major exception to the pattern is between 31°?39°W where near surface currants are northward. Estimates of the meridional heat transport associated with this steady wind-driven circulation are 0.6?0.8 ? 1015 W. Climatological data also reveal an extraordinary correlation (0.86) between seasonally varying meridional wind stress and meridional sea surface slope in the central and western equatorial Atlantic, as if the ocean were responding in a quasi-steady manner to the seasonal changes in the winds.