Variability of the Equatorial Undercurrent in the Eastern Tropical Atlantic and Gulf of Guinea

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ABSTRACTOCE-0623552The Atlantic and Pacific oceans both have an Equatorial Undercurrent, which is a strong eastward current lying near the equator. Its main role in both oceans is to supply thermocline waters from the shallow subduction zones in the subtropics to the main upwelling zones in the central and eastern part of the equatorial basins and the off-equatorial upwelling domes near the Eastern boundary. In the Pacific Ocean, this current is well-described from over a decade of intensive shipboard and time-series programs. The variability of the Equatorial Undercurrent has been closely linked to sea surface temperature variations in the eastern cold tongue region on both seasonal to interannual time scales and thus the system has important consequences for El Nino events. In the Atlantic Ocean, the Equatorial Undercurrent has received much less scientific attention. Consequently, its mean structure across the basin and its seasonal-to-interannual variability is not well understood. Particularly in the eastern part of the basin, where the Equatorial Undercurrent decays and appears to exhibit strong variability in its eastward penetration, observations are sparse and virtually no time series measurements are available. In this study, scientists from the University of Miami will study the seasonal-to-interannual variability of the current in the eastern Atlantic through moored current observations, using ADCPs, for a three year period. With these data, they will provide a description of the mean state and the variability of the current in the central and eastern Atlantic including how far the current penetrates into the Gulf of Guinea. The study will be conducted at the same time as European scientists are also investigating the circulation of the equatorial Atlantic, and thus one of the broader impacts of this study is the international collaboration. The study also will greatly improve our understanding of how oceanic processes affect sea surface temperature variability in the eastern tropical Atlantic. This variability influences the climate throughout the region. They study contributes to the goals of TACE (Tropical Atlantic Climate Experiment), which is a CLIVAR program that is designed to improve climate predictions.