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Hydrothermal heat enhances abyssal mixing in the Antarctic Circumpolar Current

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Downes, SM ORCID: 0000-0002-5595-7243, Sloyan, BM, Rintoul, SR ORCID: 0000-0002-7055-9876 and Lupton, JE 2019 , 'Hydrothermal heat enhances abyssal mixing in the Antarctic Circumpolar Current' , Geophysical Research Letters, vol. 46, no. 2 , pp. 812-821 , doi: 10.1029/2018GL080410.

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Abstract

Upwelling in the world's strongest current, the Antarctic Circumpolar Current, is thought to be driven by wind stress, surface buoyancy flux, and mixing generated from the interaction between bottom currents and rough topography. However, the impact of localized injection of heat by hydrothermal vents where the Antarctic Circumpolar Current interacts with mid-ocean ridges remains poorly understood. Here a circumpolar compilation of helium and physical measurements are used to show that while geothermal heat is transferred to the ocean over a broad area by conduction, heat transfer by convection dominates near hydrothermal vents. Buoyant hydrothermal plumes decrease stratification above the vent source and increase stratification to the south, altering the local vertical diffusivity and diapycnal upwelling within 500 m of the sea floor by an order of magnitude. Both the helium tracer and stratification signals induced by hydrothermal input are advected by the flow and influence properties downstream.

Item Type: Article
Authors/Creators:Downes, SM and Sloyan, BM and Rintoul, SR and Lupton, JE
Keywords: hydrothermal plumes, geothermal heat, Southern Ocean, vertical mixing, upwelling, Antarctic Circumpolar Current
Journal or Publication Title: Geophysical Research Letters
Publisher: Amer Geophysical Union
ISSN: 0094-8276
DOI / ID Number: 10.1029/2018GL080410
Copyright Information:

Copyright 2019 American Geophysical Union

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