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The Polar Front in Drake Passage: a composite-mean stream-coordinate view

journal contribution
posted on 2023-05-20, 17:06 authored by Annie FoppertAnnie Foppert, Donohue, KA, Watts, DR

The Polar Front (PF) is studied using 4 years of data collected by a line of current‐ and pressure‐recording inverted echo sounders in Drake Passage complemented with satellite altimetry. The location of the PF is bimodal in latitude. A northern and southern PF exist at separate times, separated geographically by a seafloor ridge—the Shackleton Fracture Zone—and hydrographically by 17 cm of geopotential height. Expressed in stream coordinates, vertical structures of buoyancy are determined with a gravest empirical mode analysis. Baroclinic velocity referenced to zero at 3500 dbar, width, and full transport (about 70 Sv) of the jets are statistically indistinguishable; the two jets alternate carrying the baroclinic transport rather than coexisting. Influences of local bathymetry and deep cyclogenesis manifest as differences in deep reference velocity structures. Downstream reference velocities of the PF‐N and PF‐S reach maximum speeds of 0.09 and 0.06 m s−1, respectively. Buoyancy fields are indicative of upwelling and poleward residual circulation at the PF. Based on potential vorticity and mixing lengths, the northern and southern PF both act as a barrier to cross‐frontal exchange while remaining susceptible to baroclinic instability.

History

Publication title

Journal of Geophysical Research: Oceans

Volume

121

Pagination

1771-1788

ISSN

2169-9275

Department/School

Institute for Marine and Antarctic Studies

Publisher

Wiley-Blackwell Publishing Inc.

Place of publication

United States

Rights statement

Copyright 2016. American Geophysical Union

Repository Status

  • Restricted

Socio-economic Objectives

Understanding climate change not elsewhere classified

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