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sufficiently accurate, during the time period, for the purposes of this study ( Bromwich and Fogt 2004 ; Yu et al. 2010 ). This section describes the primary dataset utilized as well as the methodologies used to explore the data. Of particular interest is the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim, 1979–2013) ( Dee et al. 2011 ), as it has been shown to be the best reanalysis currently available ( Bracegirdle and Marshall 2012 ; Jones and Lister 2015
sufficiently accurate, during the time period, for the purposes of this study ( Bromwich and Fogt 2004 ; Yu et al. 2010 ). This section describes the primary dataset utilized as well as the methodologies used to explore the data. Of particular interest is the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim, 1979–2013) ( Dee et al. 2011 ), as it has been shown to be the best reanalysis currently available ( Bracegirdle and Marshall 2012 ; Jones and Lister 2015
Washington . Wea. Forecasting , 18 , 600 – 613 , doi: 10.1175/1520-0434(2003)018<0600:TIOTMO>2.0.CO;2 . Brown , R. D. , and P. W. Mote , 2009 : The response of Northern Hemisphere snow cover to a changing climate . J. Climate , 22 , 2124 – 2145 , doi: 10.1175/2008JCLI2665.1 . Cassou , C. , 2008 : Intraseasonal interaction between the Madden–Julian oscillation and the North Atlantic Oscillation . Nature , 455 , 523 – 527 , doi: 10.1038/nature07286 . Cohen , J. , and D. Rind , 1991
Washington . Wea. Forecasting , 18 , 600 – 613 , doi: 10.1175/1520-0434(2003)018<0600:TIOTMO>2.0.CO;2 . Brown , R. D. , and P. W. Mote , 2009 : The response of Northern Hemisphere snow cover to a changing climate . J. Climate , 22 , 2124 – 2145 , doi: 10.1175/2008JCLI2665.1 . Cassou , C. , 2008 : Intraseasonal interaction between the Madden–Julian oscillation and the North Atlantic Oscillation . Nature , 455 , 523 – 527 , doi: 10.1038/nature07286 . Cohen , J. , and D. Rind , 1991
the extratropical extreme warm and cold events during boreal winter are associated with wave responses to tropical MJO forcing. Understanding the MJO and its teleconnection is therefore crucial for an accurate forecast of extratropical weather and climate including for North America, especially for the 2–4-week range. Despite the importance of MJO teleconnection, realistic representation of the MJO has been a longstanding challenge for global climate models ( Slingo et al. 1996 ; Lin et al. 2006
the extratropical extreme warm and cold events during boreal winter are associated with wave responses to tropical MJO forcing. Understanding the MJO and its teleconnection is therefore crucial for an accurate forecast of extratropical weather and climate including for North America, especially for the 2–4-week range. Despite the importance of MJO teleconnection, realistic representation of the MJO has been a longstanding challenge for global climate models ( Slingo et al. 1996 ; Lin et al. 2006
Forecasts (ECMWF) interim reanalysis (ERAI; Dee et al. 2011 ) for the horizontal moisture flux, downward IR, and surface heat fluxes. Arctic station-based observations indicate that reanalysis data capture the observed day-to-day variability of downward IR reasonably well ( Morcrette 2002 ). To analyze the impact of winter downward IR, with minimal impact by solar radiation, data from December to early March are analyzed. The relationships among the moisture flux, downward IR, and sea ice are analyzed
Forecasts (ECMWF) interim reanalysis (ERAI; Dee et al. 2011 ) for the horizontal moisture flux, downward IR, and surface heat fluxes. Arctic station-based observations indicate that reanalysis data capture the observed day-to-day variability of downward IR reasonably well ( Morcrette 2002 ). To analyze the impact of winter downward IR, with minimal impact by solar radiation, data from December to early March are analyzed. The relationships among the moisture flux, downward IR, and sea ice are analyzed
Grant NA14OAR4310190. We thank three anonymous reviewers for their helpful comments, the European Centre for Medium-Range Weather Forecasts for providing us with the ERA-Interim data, and NOAA’s Climate Prediction Center for providing the Arctic Oscillation index. REFERENCES Baggett , C. , and S. Lee , 2015 : Arctic warming induced by tropically forced tapping of available potential energy and the role of the planetary-scale waves . J. Atmos. Sci. , 72 , 1562 – 1568 , doi: 10.1175/JAS-D-14
Grant NA14OAR4310190. We thank three anonymous reviewers for their helpful comments, the European Centre for Medium-Range Weather Forecasts for providing us with the ERA-Interim data, and NOAA’s Climate Prediction Center for providing the Arctic Oscillation index. REFERENCES Baggett , C. , and S. Lee , 2015 : Arctic warming induced by tropically forced tapping of available potential energy and the role of the planetary-scale waves . J. Atmos. Sci. , 72 , 1562 – 1568 , doi: 10.1175/JAS-D-14
; Turner et al. 2013b ; Schneider et al. 2012 ). The paper is laid out as follows: section 2 provides an overview of the data and methods used, results are given in section 3 , and a discussion and conclusions are offered in section 4 . 2. Data and methods Monthly-mean atmospheric fields are from the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim; Dee et al. 2011 ) employed at 1.5° × 1.5° resolution for the period 1979–2015. As ERA-Interim is considered
; Turner et al. 2013b ; Schneider et al. 2012 ). The paper is laid out as follows: section 2 provides an overview of the data and methods used, results are given in section 3 , and a discussion and conclusions are offered in section 4 . 2. Data and methods Monthly-mean atmospheric fields are from the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim; Dee et al. 2011 ) employed at 1.5° × 1.5° resolution for the period 1979–2015. As ERA-Interim is considered
Geophysical Fluid Dynamics Laboratory (GFDL). The GFDL dry-dynamical-core serves as a numerical solver of the primitive equations. It is set up with a horizontal resolution of ~3 degrees (T42). The model is initialized with a climatological background flow averaged from the interim European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim; Dee et al. 2011 ) for the JJA austral winter season, from 1979 to 2012. At each time step, an additional forcing is added to the
Geophysical Fluid Dynamics Laboratory (GFDL). The GFDL dry-dynamical-core serves as a numerical solver of the primitive equations. It is set up with a horizontal resolution of ~3 degrees (T42). The model is initialized with a climatological background flow averaged from the interim European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim; Dee et al. 2011 ) for the JJA austral winter season, from 1979 to 2012. At each time step, an additional forcing is added to the
reanalysis data As the ASL resides primarily off the coast of West Antarctica where in situ observations are sparse, this study also implements atmospheric reanalysis data. Several fields from the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim; Dee et al. 2011 ) are examined to validate CAM4. ERA-Interim data were chosen over other contemporary global reanalyses because of its superior performance within the southern high latitudes ( Bracegirdle and Marshall
reanalysis data As the ASL resides primarily off the coast of West Antarctica where in situ observations are sparse, this study also implements atmospheric reanalysis data. Several fields from the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim; Dee et al. 2011 ) are examined to validate CAM4. ERA-Interim data were chosen over other contemporary global reanalyses because of its superior performance within the southern high latitudes ( Bracegirdle and Marshall
South America . Geophys. Res. Lett. , 30 , 2155 , doi: 10.1029/2003GL018277 . Son , S.-W. , A. Purich , H. H. Hendon , B. M. Kim , and L. M. Polvani , 2013 : Improved seasonal forecast using ozone hole variability? Geophys. Res. Lett. , 40 , 6231 – 6235 , doi: 10.1002/2013GL057731 . Song , H.-J. , E. Choi , G.-H. Lim , Y. H. Kim , J.-S. Kug , and S.-W. Yeh , 2011 : The central Pacific as the export region of the El Niño–Southern Oscillation sea surface
South America . Geophys. Res. Lett. , 30 , 2155 , doi: 10.1029/2003GL018277 . Son , S.-W. , A. Purich , H. H. Hendon , B. M. Kim , and L. M. Polvani , 2013 : Improved seasonal forecast using ozone hole variability? Geophys. Res. Lett. , 40 , 6231 – 6235 , doi: 10.1002/2013GL057731 . Song , H.-J. , E. Choi , G.-H. Lim , Y. H. Kim , J.-S. Kug , and S.-W. Yeh , 2011 : The central Pacific as the export region of the El Niño–Southern Oscillation sea surface
the eastern Pacific SST anomalies during DJF (e.g., Ding et al. 2012 ; Lim et al. 2013 ), the focus in Fig. 4 is on the spring into early summer as the ENSO teleconnection has been demonstrated to be strongly correlated with the SAM during this season ( Fogt and Bromwich 2006 ) and reflects a transition from asymmetric to more zonal flow ( Karoly 1990 ). The European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim, hereafter ERAI; Dee et al. 2011 ) is used to
the eastern Pacific SST anomalies during DJF (e.g., Ding et al. 2012 ; Lim et al. 2013 ), the focus in Fig. 4 is on the spring into early summer as the ENSO teleconnection has been demonstrated to be strongly correlated with the SAM during this season ( Fogt and Bromwich 2006 ) and reflects a transition from asymmetric to more zonal flow ( Karoly 1990 ). The European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim, hereafter ERAI; Dee et al. 2011 ) is used to
