The Distribution of Helium 3 in the Deep Western and Southern Indian Ocean

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Jamous, Daniel, Mémery, Laurent, Andrié, Chantal, Jean-Baptiste, Philippe, Merlivat, Liliane
• Other Authors: Laboratoire de Géochimie Isotopique Environnementale (GIS) / Université de Nîmes (GIS), Université de Nîmes (UNIMES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Hydrogéologie et de Géochimie Isotopique (LHGI), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 1992
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; Southern Ocean; The Antarctic; Pacific; Indian; Antarctic Ocean; Antarc*
• Online Access: https://hal.science/hal-03334768; https://hal.science/hal-03334768/document; https://hal.science/hal-03334768/file/jgrC1992Jamous2243.pdf; https://doi.org/10.1029/91JC02062

International audience Almost a decade after the Geochemical Ocean Sections Study Indian Expedition, the new deep 3He data from the INDIGO program give a further insight into the distribution of this tracer in the Indian Ocean. This distribution exhibits some major features related on one hand to a hydrothermal 3He input in the Gulf of Aden and on the Mid-Indian Ocean Ridge, and on the other to the origin of the water masses and to the characteristics of the deep circulation. The main pattern is a significant north-south 3He gradient, with deep waters of the southern ocean showing 83He values around 8-9% due to the influence of the Atlantic deep waters poor in 3He and relatively high values in the northern and central regions (15% to 18% between 2000 m and 3000 m depth) originating from the hydrothermal activity. In the easternmost part of the basin, the 3He values exhibit a significant increase at shallower depths (around 1000 m) probably due to the Pacific water flow through the Indonesian sills, whereas the data in the Indian sector of the Antarctic ocean show a maximum of the order of 10%, south of the Polar Front, interpreted as showing the presence of the Pacific deep waters in the Antarctic Circumpolar Current. These different aspects are summarized by mapping the horizontal distribution of the 83He maxima all over the Indian basin. This map points out some characteristics of the deep circulation but also stresses the need for further measurements in order to clarify the description of this tracer in several key areas.