The glacial eastern boundary current along the Atlantic Eurafrican continental margin

Abstract

Abstract The paleoceanography of the Bay of Biscay and of the northeast Atlantic continental margin has been reconstructed for the last glacial maximum (18,000 years ago); it is compared to the modern interglacial situation. Planktonic foraminiferal assemblages in glacial and modern sediment samples have been used to infer glacial and interglacial water mass distributions and to estimate the winter and summer sea surface temperatures. Eighteen thousand years ago, the temperate surface water masses of the modern Bay of Biscay were replaced by polar water masses (3 to 4°C) during the winter, but temperature to transitional (8 to 10°C) ones invaded the center of the day during the summer. The water masses in the Bay of Biscay and above the Ibero-Moroccan continental margin have been characterized by the steep temperature gradients across the eastern boundary current system. The latter transported surface waters, which were up to 10dgC cooler than the water masses of the central North Atlantic gyre, southwards along the continental edge.