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Kate Snow, Andrew McC. Hogg, Bernadette M. Sloyan, and Stephanie M. Downes

fluxes as a result of a warming atmosphere and increased surface freshwater fluxes. Observed freshening of AABW ( Aoki et al. 2005 ; Rintoul 2007 ; Purkey and Johnson 2010 , 2013 ) is linked with evidence of increased precipitation and glacial melt around Antarctica (e.g., Jullion et al. 2013 ). AABW observations also indicate a warming and contraction of the densest water mass ( Purkey and Johnson 2010 , 2013 ). Warming of AABW remains a significant contributor to sea level rise through

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Hyo-Seok Park, Sukyoung Lee, Seok-Woo Son, Steven B. Feldstein, and Yu Kosaka

anomalies ( Deser et al. 2000 ), but increased downward IR in Arctic winter was also proposed as a factor for changing sea ice thickness ( Francis and Hunter 2006 ). In particular, recent studies have found that poleward moisture fluxes into the Arctic associated with anomalous wintertime large-scale circulations increase downward IR at the surface ( Lee et al. 2011 ; Yoo et al. 2012a ; Woods et al. 2013 ). While one may wonder if an increase in downward IR can reduce sea ice thickness during the

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Xiaofang Feng, Qinghua Ding, Liguang Wu, Charles Jones, Ian Baxter, Robert Tardif, Samantha Stevenson, Julien Emile-Geay, Jonathan Mitchell, Leila M. V. Carvalho, Huijun Wang, and Eric J. Steig

vectors (10 4 Pa m 2 s −2 ; vectors less than 10 3 Pa m 2 s −2 are omitted) denote the wave activity flux ( Plumb 1985 ) associated with the corresponding EOF pattern. The total variance explained by each EOF is indicated in the parentheses. In (c), stippling indicates statistically significant correlations at the 95% confidence level. Correlations of surface temperatures with the principal component of EOF1 (PC1) show a warming Arctic over Greenland and northeastern Canada, cooling over the

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M. Nuncio and Xiaojun Yuan

et al. 2008 ). The impact of El Niño–Southern Oscillation (ENSO) over southern Australia and China occurs through ENSO’s coherence with IOD ( Cai et al. 2011 ). Sea ice, on the other hand, is one of the highly varying cryospheric parameters. The growth and decay of sea ice on different time scales, ranging from seasonal to decadal, is associated with numerous processes. The Antarctic Oscillation (AAO) influences sea ice by means of anomalous mean surface heat flux and ice advection ( Liu et al

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Aaron B. Wilson, David H. Bromwich, and Keith M. Hines

simulation and all seasons. Several authors (e.g., Seager et al. 2003 ; Lim et al. 2013 ) have demonstrated that low-frequency El Niño variability can force a SAM− state through the modulation of the SH STJ that imparts a decrease in transient momentum flux convergence at high latitudes (weaker zonal flow) and an equatorward shift in the eddy-driven jet. While there is a tendency for such an occurrence, this does not necessarily mean a SAM− event will always occur with El Niño, as a number of recent

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Jin-Yi Yu, Houk Paek, Eric S. Saltzman, and Tong Lee

the SAM: an eddy–mean flow interaction mechanism in the troposphere and a stratospheric pathway mechanism. The eddy–mean flow interaction mechanism requires that, during El Niño events, the increased meridional temperature gradient associated with a tropical tropospheric warming ( Chiang and Sobel 2002 ) produce a strengthened and equatorward-displaced subtropical jet. The strengthened subtropical jet then affects the propagation of transient eddies to change the location of eddy momentum flux

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Robert A. Tomas, Clara Deser, and Lantao Sun

). Without the insulating effect of sea ice, the newly exposed warm surface waters will flux heat and water vapor into the overlying atmosphere, warming and moistening the lower troposphere (e.g., Screen and Simmonds 2010 ). Winds will mix the excess heat and moisture southward over the adjacent continents, increasing temperature and precipitation at high latitudes ( Deser et al. 2010 ). Northern land areas are also expected to experience a decrease in surface temperature variance ( Screen et al. 2015a

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Michael Goss, Steven B. Feldstein, and Sukyoung Lee

positive SWI 1 and the deceleration of the stratospheric polar vortex, and vice versa for negative SWI 1 , is associated with vertical wave activity propagation from the troposphere into the stratosphere, we calculate lagged composites of the meridional heat flux at 100 hPa. The results are shown in the top (bottom) panel of Fig. 11 , calculated as [υ* T *]′, where υ is the meridional component of the wind at 100 hPa, T is the temperature at 100 hPa, the square brackets denote the zonal mean, an

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Bradley P. Goodwin, Ellen Mosley-Thompson, Aaron B. Wilson, Stacy E. Porter, and M. Roxana Sierra-Hernandez

during cool ENSO (La Niña) events ( Vincent 1994 ). This generates a positive feedback with poleward transient eddy momentum flux that interacts with the polar front to increase cyclonic activity in the South Pacific sector of the Antarctic coast ( Chen et al. 1996 ). Conversely, during negative SAM the circumpolar trough is weakened as the high-latitude storm track relaxes to the north while warm ENSO (El Niño) events shift the SPCZ equatorward as well, directing cyclones away from the AP and toward

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Xiaojun Yuan, Michael R. Kaplan, and Mark A. Cane

to tropical SST changes ( Chen et al. 1996 ; Bals-Elsholz et al. 2001 ); 3) anomalous mean meridional and zonal circulations and associated heat fluxes ( Carleton and Whalley 1988 ; Cullather et al. 1996 ; Kreutz et al. 2000 ; Liu et al. 2002 ; Seager et al. 2003 ; Liu et al. 2004 ; Yuan 2004 ); and 4) altered transient eddy activity ( Carleton and Carpenter 1990 ; Carleton and Fitch 1993 ; Sinclair et al. 1997 ; Carleton and Song 2000 ). Through the atmospheric connection, ENSO events

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