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L. St. Laurent, A. C. Naveira Garabato, J. R. Ledwell, A. M. Thurnherr, J. M. Toole, and A. J. Watson

1981 ; Polzin 2004 ; MacKinnon and Winters 2005 ); that energy in turn can support turbulence and mixing of the ocean’s buoyancy field. In contrast to most midocean regions of the subtropical basins, the Southern Ocean is a site of strong, deep-reaching geostrophic flow: the Antarctic Circumpolar Current (ACC). The ACC consists of a series of frontal zones where the flow is most enhanced—the Southern ACC Front (SACCF) to the south, the Polar Front (PF) in the middle, and the Subantarctic Front

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Jean-Baptiste Sallée, Kevin Speer, Steve Rintoul, and S. Wijffels

, associated with subduction of Subantartic Mode Water (SAMW) ( Speer et al. 2000 ; Karsten and Marshall 2002 ). This must involve a combination of the strong northward Ekman transport and geostrophic transport and be balanced by eddy processes of diffusion and a southward eddy-induced advection. We aim to revisit these components to the extent possible with existing observations. Because of data from the Argo program, we have, for the first time in the Southern Ocean, access to an accurate month

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James A. Screen, Nathan P. Gillett, Alexey Yu Karpechko, and David P. Stevens

models. Future changes in the winds (closely related to the SAM trend) are key to the projected changes in the Southern Ocean and a major component of intermodel variability results from surface wind differences in the CMIP3 models ( Sen Gupta et al. 2009 ). The reanalyses’s SLP responses to the SAM exhibit zonal asymmetry in the central Pacific sector, which is less pronounced in the simulations. This error propagates to other atmospheric fields including the turbulent heat fluxes. The reanalyses

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Daniel T. McCoy, Dennis L. Hartmann, and Daniel P. Grosvenor

1. Introduction McCoy et al. (2014 , hereinafter Part I) studied the effect on the reflected shortwave radiation (SW ↑ ) of the observed seasonal cycles of cloud properties derived from an array of remote sensing platforms in the Southern Ocean region (40°–60°S). Calculations of SW ↑ over the Southern Ocean were performed based on remotely sensed cloud properties. This was accomplished by synthesizing the observed cloud properties in the Southern Ocean into a data structure containing cloud

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Katherine A. Adams, Philip Hosegood, John R. Taylor, Jean-Baptiste Sallée, Scott Bachman, Ricardo Torres, and Megan Stamper

1. Introduction The Southern Ocean hosts the most energetic current system in the world, the Antarctic Circumpolar Current (ACC). Zonally unbounded by land, the ACC connects ocean basins and transports an estimated 173 Sv (1 Sv ≡ 10 6 m 3 s −1 ) through the Drake Passage ( Donohue et al. 2016 ). The ACC is predominantly in geostrophic balance with sea surface height (SSH) gradients and lateral density gradients, hereafter fronts. Large-scale instabilities in the balanced ACC flow cause

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Bernadette M. Sloyan and Igor V. Kamenkovich

1. Introduction The Southern Ocean’s Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) are two globally significant upper-ocean water masses that circulate in all of the Southern Hemisphere subtropical gyres and cross the equator to enter the North Pacific and North Atlantic Oceans. They are important components of the ocean heat and freshwater transport. SAMW and AAIW ventilate and resupply nutrients to the upper ocean, maintaining a substantial proportion of the global

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Carolina O. Dufour, Stephen M. Griffies, Gregory F. de Souza, Ivy Frenger, Adele K. Morrison, Jaime B. Palter, Jorge L. Sarmiento, Eric D. Galbraith, John P. Dunne, Whit G. Anderson, and Richard D. Slater

1. Introduction The Southern Ocean (south of 30°S) is a key region for the meridional transport of heat and biogeochemical tracers and one of the few places in the global ocean where ancient deep waters are exposed to the atmosphere ( Marshall and Speer 2012 ; Talley 2013 ; Morrison et al. 2015 ). Within the latitudes of the Antarctic Circumpolar Current (ACC), vigorous wind-driven upwelling brings old waters, poor in oxygen and rich in natural carbon and nutrients, to the surface. Once

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Kaitlin A. Naughten, Katrin J. Meissner, Benjamin K. Galton-Fenzi, Matthew H. England, Ralph Timmermann, and Hartmut H. Hellmer

number of ocean models that simulate ice shelf thermodynamics in this manner [see Dinniman et al. (2016) and references therein], but future projections with these models have so far been limited. By forcing FESOM with atmospheric output from the CMIP5 experiments, we obtain projections of ice shelf melt rates throughout the twenty-first century, as well as continental shelf water mass properties, sea ice processes, and Southern Ocean circulation. FESOM has previously been used for future

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Sunke Schmidtko and Gregory C. Johnson

1. Introduction Antarctic Intermediate Water (AAIW) is a very prominent water mass that lies above the deep water and spreads below the subtropical thermocline in the Southern Hemisphere. AAIW has long been identified by a pronounced salinity minimum from 600- to 1000-m depth ( Wüst 1936 , 1–288) found north of the Antarctic Circumpolar Current (ACC) in all three oceans ( Fig. 1 ). McCartney (1977) suggested that AAIW is formed primarily in the southeast Pacific Ocean just equatorward of the

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Richard G. Williams, Chris Wilson, and Chris W. Hughes

the ocean, eddy activity appears to be similarly localized and persistent. Local maxima in eddy kinetic energy (EKE) broadly reflect where there are strong time-mean currents, along the Antarctic Circumpolar Current in the Southern Ocean and over the extension of western boundary currents into the interior of ocean basins. The starting point of this study is the assumption that ocean eddy variability is primarily formed through baroclinic instability ( Gill et al. 1974 ), although over some

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