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Kevin M. Schmidt, Sebastiaan Swart, Chris Reason, and Sarah-Anne Nicholson

1. Introduction Mid- to high-latitude regions in the Southern Ocean are host to the strongest wind fields at the ocean surface. These strong winds (speeds > 20 m s −1 ; Yuan 2004 ) significantly impact upper-ocean properties and processes, such as mixed layer dynamics, Ekman processes, and air–sea exchange. Exchanges in heat, moisture, and momentum at the air–sea interface are facilitated by sea surface winds. In addition to driving physical processes at the sea surface, these winds also have

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David P. Schneider and David B. Reusch

1. Introduction Several aspects of observed climate changes over the Southern Ocean and Antarctica have been challenging to explain, lowering confidence in projections of future changes. For example, there is no single agreed-upon explanation for the increase in Antarctic sea ice extent during the satellite era (e.g., Holland 2014 ; Fan et al. 2014 ; Bintanja et al. 2013 ), little consensus on the response of the Antarctic Circumpolar Current (ACC) to the observed increase in the westerly

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A. Bodas-Salcedo, K. D. Williams, P. R. Field, and A. P. Lock

radiative effect (CRE) in several models, which leads to an excess in surface downwelling solar radiation (SDSR). More recently, Trenberth and Fasullo (2010) show that the third Coupled Model Intercomparison Project (CMIP3; Meehl et al. 2005 ) models show a consistent positive bias in the absorbed shortwave radiation (ASR) over the southern oceans (in the belt between 45° and 60°S). This region also shows a strong negative trend in the ASR in the projections for the end of the twenty-first century

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Christopher C. Chapman, Andrew McC. Hogg, Andrew E. Kiss, and Stephen R. Rintoul

tracks are found near the cores of the midlatitude jet streams ( Blackmon 1976 ) but show zonal asymmetry. In the Northern Hemisphere, there are two distinct storm tracks: one over the North Pacific basin, another over the North Atlantic basin ( Hoskins and Hodges 2002 ). The storm tracks in the Southern Hemisphere are found primarily over the South Atlantic and Indian Ocean basins, although the zonal asymmetry of the EKE fields is not as strong as that of the Northern Hemisphere ( Hoskins and Hodges

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Ryan Abernathey, John Marshall, and David Ferreira

1. Introduction Changes in wind stress over the Southern Ocean may be responsible for modulating the strength of the global meridional overturning circulation (MOC) ( Toggweiler 2009 ). Such wind-induced changes in the MOC could help regulate glacial–interglacial cycles by venting CO 2 from the deep ocean to the atmosphere ( Toggweiler and Russell 2008 ; Anderson et al. 2009 ; Marshall and Speer 2011 ). The mechanism could also play an important role in future climate change; the westerlies

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K. Shafer Smith and John Marshall

, for enhanced particle exchange at the steering level. Satellite altimetric observations of the Southern Ocean do suggest the presence of large-scale waves that propagate downstream in the Antarctic Circumpolar Current (ACC) at a rate significantly slower (25%) than that of surface currents. This was anticipated by Hughes (1996) in studies of an eddy-resolving model of the Southern Ocean where it was argued that the eastward flow of the ACC turned it into a Rossby waveguide. The top panel of Fig

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Brian J. Butterworth and Scott D. Miller

1. Introduction Air–sea exchange at high latitudes in the Southern Hemisphere affects the global climate system. The fluxes of momentum and heat affect cold-water formation and the global oceanic circulation ( Rintoul et al. 2010 ), and the Southern Ocean is responsible for roughly half the CO 2 absorbed by the world’s oceans ( Takahashi et al. 2012 ). The Southern Ocean is also changing—warming more rapidly than the global average sea temperature ( Rintoul et al. 2010 )—and some studies

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Emma J. D. Boland, Emily Shuckburgh, Peter H. Haynes, James R. Ledwell, Marie-José Messias, and Andrew J. Watson

only estimated diapycnal diffusivity but also provoked a lively debate about other mixing processes that lead to horizontal spreading of tracer and, acting in opposition to quasi-horizontal deformation by the mesoscale eddy field, limit the thinning of tracer filaments. In this paper, we examine whether corresponding information on such mixing processes can be obtained from other tracer measurements, such as those made in the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES

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David P. Schneider, Clara Deser, and Tingting Fan

(EOF) of extratropical, lower-tropospheric geopotential height anomalies ( Thompson and Wallace 2000 ). The positive trend in the SAM has been linked with a reduction in the Southern Ocean carbon sink (e.g., Le Quéré et al. 2007 ; Lovenduski et al. 2008 ), shifts in the spatial distribution of precipitation ( Kang et al. 2011 ; Previdi and Polvani 2014 ), and cooling trends in East Antarctic surface climate ( Marshall 2007 ; Nicolas and Bromwich 2014 ). There have also been significant regional

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A. Köhl, D. Stammer, and B. Cornuelle

–cooling cycle. In contrast, the variability in the Tropics originates from the changes of the flow field on seasonal time scales and from Rossby wave activity there. However, most of the enhanced variability on the western and eastern sides of the Pacific Ocean and in the Indian Ocean are associated with the 1997/98 ENSO event. In the Southern Ocean, enhanced variability southwest of Australia and upstream of Drake Passage is associated with high-latitude barotropic activity. Figure 6 shows the mean

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