Jet-topography interactions affect energy pathways to the deep Southern Ocean

Alice Barthel*, Andrew McC. Hogg, Stephanie Waterman, Shane Keating

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)

    Abstract

    In the Southern Ocean, strong eastward ocean jets interact with large topographic features, generating eddies that feed back onto the mean flow. Deep-reaching eddies interact with topography, where turbulent dissipation and generation of internal lee waves play an important role in the ocean's energy budget.However, eddy effects in the deep ocean are difficult to observe and poorly characterized. This study investigates the energy contained in eddies at depth, when an ocean jet encounters topography. This study uses a two-layer ocean model in which an imposed unstable jet encounters a topographic obstacle (either a seamount or a meridional ridge) in a configuration relevant to an Antarctic Circumpolar Current frontal jet. The authors find that the presence of topography increases the eddy kinetic energy (EKE) at depth but that the dominant processes generating this deep EKE depend on the shape and height of the obstacle as well as on the baroclinicity of the jet before it encounters topography. In cases with high topography, horizontal shear instability is the dominant source of deepEKE,while a flat bottomor a strongly sheared inflowleads to deepEKEbeing generated primarily through baroclinic instability. These results suggest that the deep EKE is set by an interplay between the inflowing jet properties and topography and imply that the response of deep EKE to changes in the Southern Ocean circulation is likely to vary across locations depending on the topography characteristics.

    Original languageEnglish
    Pages (from-to)1799-1816
    Number of pages18
    JournalJournal of Physical Oceanography
    Volume47
    Issue number7
    DOIs
    Publication statusPublished - 1 Jul 2017

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