The dataset provides the planktonic foraminiferal species total count and the Globorotalia truncatulinoides dextral/sinistral coiling ratio, as well as the Agulhas Leakage Efficiency (ALE) Index for IODP Expedition 391, Site U1575, covering the Early-Middle to Late Pleistocene time interval. The drilled site was cored along the Tristan-Gough-Walvis Ridge (TGW) seamount track, which, in turn, is situated in the northernmost sector of the Benguela Upwelling System or BUS (Southeastern Atlantic Ocean). The BUS region is interested by several water masses, among which the Benguela Oceanic Current (BOC) and the South Atlantic Central Waters (SACWs). The BOC represents a cold surface water mass flowing along the coast of Africa, from Cape Town (34°S) to Walvis Bay (23°S). The SACWs, instead, are warm, oligotrophic subsurface water masses, located in the Angola Basin, north of the BUS. They can interact with the colder water of the BOC during time, causing the shift of the Angola-Benguela thermal front (ABF). Furthermore, warm waters from the Indian Ocean can access the BUS through a mechanism known as the Agulhas Leakage. The collected dataset was used to better understand variations in the local paleoceanographic conditions (stability of the thermocline) induced by the interactions of the previously mentioned water masses. Specifically, the foraminifera content, the Globorotalia truncatulinoides dextral/sinistral coiling ratio, as well as the Agulhas Leakage Efficiency (ALE) Index were applied to characterize the different water masses as well as to reconstruct their interplay during the Early-Middle to Late Pleistocene. The determination of the paleoceanographic conditions in the BUS further allowed to associate their variations to climatic processes (such as Benguela Niño/Niña-like stages and deglaciation intervals).
