The Climate-system Historical Forecast Project: do stratosphere-resolving models make better seasonal climate predictions in boreal winter?

Thumbnail Image
Full text at PDC
Publication Date
Iza San Juan, Maddalen
otros, ...
Advisors (or tutors)
Journal Title
Journal ISSN
Volume Title
Google Scholar
Research Projects
Organizational Units
Journal Issue
Using an international, multi-model suite of historical forecasts from the World Climate Research Programme (WCRP) Climate-system Historical Forecast Project (CHFP), we compare the seasonal prediction skill in boreal wintertime between models that resolve the stratosphere and its dynamics (high-top') and models that do not (low-top'). We evaluate hindcasts that are initialized in November, and examine the model biases in the stratosphere and how they relate to boreal wintertime (December-March) seasonal forecast skill. We are unable to detect more skill in the high-top ensemble-mean than the low-top ensemble-mean in forecasting the wintertime North Atlantic Oscillation, but model performance varies widely. Increasing the ensemble size clearly increases the skill for a given model. We then examine two major processes involving stratosphere-troposphere interactions (the El Niño/Southern Oscillation (ENSO) and the Quasi-Biennial Oscillation (QBO)) and how they relate to predictive skill on intraseasonal to seasonal time-scales, particularly over the North Atlantic and Eurasia regions. High-top models tend to have a more realistic stratospheric response to El Niño and the QBO compared to low-top models. Enhanced conditional wintertime skill over high latitudes and the North Atlantic region during winters with El Niño conditions suggests a possible role for a stratospheric pathway.
© Wiley-Blackwell. All rights reserved. Artículo firmado por 24 autores. We acknowledge the WCRP/CLIVAR Working Group on Seasonal to Interannual Prediction (WGSIP) for establishing the Climate-system Historical Forecast Project (CHFP: Kirtman and Pirani, 2009) and the Centro de Investigaciones del Mar y la Atmósfera (CIMA) for providing the model output. We also thank the data providers for making the model output available through CHFP. We have no potential sources of conflict of interest. The contribution of AYK is funded by the Academy of Finland, project no. 286298.
Unesco subjects
Arribas, A., M. Glover, A. Maidens, K. Peterson, M. Gordon, C. MacLachlan, R. Graham, D. Fereday, J. Camp, A. A. Scaife, P. Xavier, P. McLean, A. Colman, and S. Cusack, 2011: The GloSea4 Ensemble Prediction System for Seasonal Forecasting. Mon. Weather Rev., 139, 1891–1910, doi:10.1175/2010MWR3615.1. Baehr, J., K. Fröhlich, M. Botzet, D. I. V Domeisen, L. Kornblueh, D. Notz, R. Piontek, H. Pohlmann, S. Tietsche, and W. A. Müller, 2015: The prediction of surface temperature in the new seasonal prediction system based on the MPI-ESM coupled climate model. Clim. Dyn., 44, 2723–2735, doi:10.1007/s00382-014-2399-7. Baldwin, M. P., L. J. Gray, T. J. Dunkerton, K. Hamilton, P. H. Haynes, W. J. Randel, J. R. Holton, M. J. Alexander, I. Hirota, T. Horinouchi, D. B. A. Jones, J. S. Kinnersley, C. Marquardt, K. Sato, and M. Takahashi, 2001: The quasi-biennial oscillation. Rev. Geophys., 39, 179–229, doi:10.1029/1999RG000073. Baldwin, M. P., D. B. Stephenson, D. W. J. Thompson, T. J. Dunkerton, A. J. Charlton, A. O’Neill, and David W. J. Thompson, 2003: Stratospheric Memory and Skill of Extended-Range Weather Forecasts. Science (80-. )., 301, 636–640, doi:10.1126/science.1087143. Becker, E., H. van den Dool, and Q. Zhang, 2014: Predictability and Forecast Skill in NMME. J. Clim., 27, 5891–5906, doi:10.1175/JCLI-D-13-00597.1. Boer, G. J., and K. Hamilton, 2008: QBO influence on extratropical predictive skill. Clim. Dyn., 31, 987–1000, doi:10.1007/s00382-008-0379-5. Butler, A. H., and L. M. Polvani, 2011: El Niño, La Niña, and stratospheric sudden warmings: A reevaluation in light of the observational record. Geophys. Res. Lett., 38, doi:10.1029/2011GL048084. ——, ——, and C. Deser, 2014: Separating the stratospheric and tropospheric pathways of El Niño–Southern Oscillation teleconnections. Environ. Res. Lett., 9, 024014. Cagnazzo, C., and E. Manzini, 2009: Impact of the Stratosphere on the Winter Tropospheric Teleconnections between ENSO and the North Atlantic and European Region. J. Clim., 22, 1223–1238, doi:10.1175/2008JCLI2549.1. Charlton-Perez, A. J., M. P. Baldwin, T. Birner, R. X. Black, A. H. Butler, N. Calvo, N. A. Davis, E. P. Gerber, N. Gillett, S. Hardiman, J. Kim, K. Krüger, Y. Y. Lee, E. Manzini, B. A. McDaniel, L. Polvani, T. Reichler, T. A. Shaw, M. Sigmond, S. W. Son, M. Toohey, L. Wilcox, S. Yoden, B. Christiansen, F. Lott, D. Shindell, S. Yukimoto, and S. Watanabe, 2013: On the lack of stratospheric dynamical variability in low-top versions of the CMIP5 models. J. Geophys. Res. Atmos., 118, 2494–2505. Chen, M., W. Wang, and A. Kumar, 2013: Lagged Ensembles, Forecast Configuration, and Seasonal Predictions. Mon. Weather Rev., 141, 3477–3497, doi:10.1175/MWRD-12-00184.1. Cohen, J., and J. Jones, 2011: A new index for more accurate winter predictions. Geophys. Res. Lett., 38, doi:10.1029/2011GL049626. Cottrill, A., H. H. Hendon, E.-P. Lim, S. Langford, K. Shelton, A. Charles, D. McClymont, D. Jones, and Y. Kuleshov, 2013: Seasonal Forecasting in the Pacific Using the Coupled Model POAMA-2. Weather Forecast., 28, 668–680, doi:10.1175/WAF-D-12-00072.1. Danabasoglu, G., W. G. Large, and B. P. Briegleb, 2010: Climate impacts of parameterized Nordic Sea overflows. J. Geophys. Res. Ocean., 115, doi:10.1029/2010JC006243. Dee, D. P., S. M. Uppala, A. J. Simmons, P. Berrisford, P. Poli, S. Kobayashi, U. Andrae, M. A. Balmaseda, G. Balsamo, P. Bauer, P. Bechtold, A. C. M. Beljaars, L. van de Berg, J. Bidlot, N. Bormann, C. Delsol, R. Dragani, M. Fuentes, A. J. Geer, L. Haimberger, S. B. Healy, H. Hersbach, E. V. Hólm, L. Isaksen, P. Kållberg, M. Köhler, M. Matricardi, A. P. McNally, B. M. Monge Sanz, J.-J. Morcrette, B.-K. Park, C. Peubey, P. de Rosnay, C. Tavolato, J.-N. Thépaut, and F. Vitart, 2011: The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q. J. R. Meteorol. Soc., 137, 553–597, doi:10.1002/qj.828. DelSole, T., J. Nattala, and M. K. Tippett, 2014: Skill Improvement From Increased Ensemble Size and Model Diversity. Geophys. Res. Lett., 2014GL060133, doi:10.1002/2014GL060133. Doblas Reyes, F. J., V. Pavan, and D. B. Stephenson, 2003: The skill of multi-model seasonal forecasts of the wintertime North Atlantic Oscillation. Clim. Dyn., 21, 501-514, doi:10.1007/s00382-003-0350-4. Domeisen, D. I. V., A. H. Butler, K. Fröhlich, M. Bittner, W. A. Müller, and J. Baehr, 2015: Seasonal Predictability over Europe Arising from El Niño and Stratospheric Variability in the MPI-ESM Seasonal Prediction System. J. Clim., 28, 256–271, doi:10.1175/JCLI-D-14-00207.1. Douville, H., 2009: Stratospheric polar vortex influence on Northern Hemisphere winter climate variability. Geophys. Res. Lett., 36, L18703, doi:10.1029/2009GL039334. Dunkerton, T., and M. Baldwin, 1991: Quasi-Biennial Modulation of Planetary-Wave Fluxes in the Northern-Hemisphere Winter. J. Atmos. Sci., 48, 1043–1061, doi:10.1175/1520-0469(1991)048<1043:QBMOPW>2.0.CO;2. Eade, R., D. Smith, A. Scaife, E. Wallace, N. Dunstone, L. Hermanson, and N. Robinson, 2014: Do seasonal-to-decadal climate predictions underestimate the predictability of the real world? Geophys. Res. Lett., 41, 2014GL061146, doi:10.1002/2014GL061146. Ern, M., F. Ploeger, P. Preusse, J. C. Gille, L. J. Gray, S. Kalisch, M. G. Mlynczak, J. M. Russell, and M. Riese, 2014: Interaction of gravity waves with the QBO: A satellite perspective. J. Geophys. Res. Atmos., 119, 2329–2355, doi:10.1002/2013JD020731. Fereday, D. R., A. Maidens, A. Arribas, A. A. Scaife, and J. R. Knight, 2012: Seasonal forecasts of northern hemisphere winter 2009/10. Environ. Res. Lett., 7, 034031, doi:10.1088/1748-9326/7/3/034031. Fletcher, C. G., and P. J. Kushner, 2011: The Role of Linear Interference in the Annular Mode Response to Tropical SST Forcing. J. Clim., 24, 778–794, doi:10.1175/2010JCLI3735.1. García Herrera, R., N. Calvo, R. R. García, and M. a. Giorgetta, 2006: Propagation of ENSO temperature signals into the middle atmosphere: A comparison of two general circulation models and ERA-40 reanalysis data. J. Geophys. Res., 111, D06101, doi:10.1029/2005JD006061. García Serrano, J., C. Frankignoul, G. Gastineau, and Á. de la Cámara, 2015: On the predictability of the winter Euro-Atlantic climate: lagged influence of autumn Arctic sea-ice. J. Clim., doi:10.1175/JCLI-D-14-00472.1. Garfinkel, C. I., and D. L. Hartmann, 2007: Effects of the El Niño–Southern Oscillation and the Quasi-Biennial Oscillation on polar temperatures in the stratosphere. J. Geophys. Res., 112, D19112, doi:10.1029/2007JD008481. ——, and ——, 2008: Different ENSO teleconnections and their effects on the stratospheric polar vortex. J. Geophys. Res., 113, D18114, doi:10.1029/2008JD009920. ——, and ——, 2010: Influence of the quasi-biennial oscillation on the North Pacific and El Niño teleconnections. J. Geophys. Res., 115, D20116, doi:10.1029/2010JD014181. ——, M. M. Hurwitz, D. W. Waugh, and A. H. Butler, 2013: Are the teleconnections of Central Pacific and Eastern Pacific El Niño distinct in boreal wintertime? Clim. Dyn., 1–18, doi:10.1007/s00382-012-1570-2. Gerber, E. P., and L. M. Polvani, 2009: Stratosphere–Troposphere Coupling in a Relatively Simple AGCM: The Importance of Stratospheric Variability. J. Clim., 22, 1920–1933, doi:10.1175/2008JCLI2548.1. Gerber, E. P., C. Orbe, and L. M. Polvani, 2009: Stratospheric influence on the tropospheric circulation revealed by idealized ensemble forecasts. Geophys. Res. Lett., 36, L24801, doi:10.1029/2009GL040913. Gerber, E. P., A. Butler, N. Calvo, A. Charlton-Perez, M. Giorgetta, E. Manzini, J. Perlwitz, L. M. Polvani, F. Sassi, A. A. Scaife, T. A. Shaw, S.-W. Son, and S. Watanabe, 2012: Assessing and Understanding the Impact of Stratospheric Dynamics and Variability on the Earth System. Bull. Am. Meteorol. Soc., 93, 845–859, doi:10.1175/BAMS-D-11-00145.1. Hardiman, S. C., N. Butchart, T. J. Hinton, S. M. Osprey, and L. J. Gray, 2012: The Effect of a Well-Resolved Stratosphere on Surface Climate: Differences between CMIP5 Simulations with High and Low Top Versions of the Met Office Climate Model. J. Clim., 25, 7083–7099, doi:10.1175/JCLI-D-11-00579.1. Haynes, P. H., 1998: The latitudinal structure of the quasi-biennial oscillation. Q. J. R. Meteorol. Soc., 124, 2645–2670, doi:10.1002/qj.49712455206. Holton, J. R., and H.-C. Tan, 1980: The Influence of the Equatorial Quasi-Biennial Oscillation on the Global Circulation at 50 mb. J. Atmos. Sci., 37, 2200–2208, doi:10.1175/1520-0469(1980)037<2200:TIOTEQ>2.0.CO;2. Hurwitz, M. M., N. Calvo, C. I. Garfinkel, A. H. Butler, S. Ineson, C. Cagnazzo, E. Manzini, and C. Peña Ortiz, 2014: Extra-tropical atmospheric response to ENSO in the CMIP5 models. Clim. Dyn., doi:10.1007/s00382-014-2110-z. Imada, Y., H. Tatebe, M. Ishii, Y. Chikamoto, M. Mori, M. Arai, M. Watanabe, and M. Kimoto, 2015: Predictability of Two Types of El Niño Assessed Using an Extended Seasonal Prediction System by MIROC. Mon. Weather Rev., doi:10.1175/MWR-D-15-0007.1. Ineson, S., and A. A. Scaife, 2009: The role of the stratosphere in the European climate response to El Niño. Nat. Geosci., 2, 32–36, doi:10.1038/ngeo381. Iza, M., and N. Calvo, 2015: Role of Stratospheric Sudden Warmings on the response to Central Pacific El Niño. Geophys. Res. Lett., 42, 2482–2489, doi:10.1002/2014GL062935. Jungclaus, J. H., N. Fischer, H. Haak, K. Lohmann, J. Marotzke, D. Matei, U. Mikolajewicz, D. Notz, and J. S. von Storch, 2013: Characteristics of the ocean simulations in the Max Planck Institute Ocean Model (MPIOM) the ocean component of the MPI-Earth system model. J. Adv. Model. Earth Syst., 5, 422–446, doi:10.1002/jame.20023. Kang, D., M.-I. Lee, J. Im, D. Kim, H.-M. Kim, H.-S. Kang, S. D. Schubert, A. Arribas, and C. MacLachlan, 2014: Prediction of the Arctic Oscillation in boreal winter by dynamical seasonal forecasting systems. Geophys. Res. Lett., 41, 2014GL060011, doi:10.1002/2014GL060011. Keeley, S. P. E., R. T. Sutton, and L. C. Shaffrey, 2009: Does the North Atlantic Oscillation show unusual persistence on intraseasonal timescales? Geophys. Res. Lett., 36, doi:10.1029/2009GL040367. Kharin, V. V, F. W. Zwiers, and N. Gagnon, 2001: Skill of seasonal hindcasts as a function of the ensemble size. Clim. Dyn., 17, 835–843, doi:10.1007/s003820100149. Kidston, J., A. A. Scaife, S. C. Hardiman, D. M. Mitchell, N. Butchart, M. P. Baldwin, and L. J. Gray, 2015: Stratospheric influence on tropospheric jet streams, storm tracks and surface weather. Nat. Geosci, 8, 433–440. Kim, H.-M., P. J. Webster, and J. A. Curry, 2012: Seasonal prediction skill of ECMWF System 4 and NCEP CFSv2 retrospective forecast for the Northern Hemisphere Winter. Clim. Dyn., 39, 2957–2973, doi:10.1007/s00382-012-1364-6. Kirtman, B., and A. Pirani, 2009: The State of the Art of Seasonal Prediction: Outcomes and Recommendations from the First World Climate Research Program Workshop on Seasonal Prediction. Bull. Am. Meteorol. Soc., 90, 455–458, doi:10.1175/2008BAMS2707.1. Kumar, A., 2009: Finite Samples and Uncertainty Estimates for Skill Measures for Seasonal Prediction. Mon. Weather Rev., 137, 2622–2631, doi:10.1175/2009MWR2814.1. ——, and M. P. Hoerling, 2000: Analysis of a Conceptual Model of Seasonal Climate Variability and Implications for Seasonal Prediction. Bull. Am. Meteorol. Soc., 81, 255–264, doi:10.1175/1520-0477(2000)081<0255:AOACMO>2.3.CO;2. Kuroda, Y., 2008: Role of the stratosphere on the predictability of medium-range weather forecast: A case study of winter 2003–2004. Geophys. Res. Lett., 35, L19701, doi:10.1029/2008GL034902. Lee, T., and M. J. McPhaden, 2010: Increasing intensity of El Niño in the central-equatorial Pacific. Geophys. Res. Lett., 37, L14603, doi:10.1029/2010GL044007. MacLachlan, C., A. Arribas, K. A. Peterson, A. Maidens, D. Fereday, A. A. Scaife, M. Gordon, M. Vellinga, A. Williams, R. E. Comer, J. Camp, P. Xavier, and G. Madec, 2015: Global Seasonal forecast system version 5 (GloSea5): a high-resolution seasonal forecast system. Q. J. R. Meteorol. Soc., 141, 1072–1084, doi:10.1002/qj.2396. Manzini, E., M. a. Giorgetta, M. Esch, L. Kornblueh, and E. Roeckner, 2006: The Influence of Sea Surface Temperatures on the Northern Winter Stratosphere: Ensemble Simulations with the MAECHAM5 Model. J. Clim., 19, 3863–3881, doi:10.1175/JCLI3826.1. Marshall, A. G., and A. a. Scaife, 2009: Impact of the QBO on surface winter climate. J. Geophys. Res., 114, D18110, doi:10.1029/2009JD011737. ——, and ——, 2010: Improved predictability of stratospheric sudden warming events in an atmospheric general circulation model with enhanced stratospheric resolution. J. Geophys. Res., 115, D16114, doi:10.1029/2009JD012643. Maycock, A. C., S. P. E. Keeley, A. J. Charlton-Perez, and F. J. Doblas-Reyes, 2011: Stratospheric circulation in seasonal forecasting models: implications for seasonal prediction. Clim. Dyn., 36, 309–321, doi:10.1007/s00382-009-0665-x. Merryfield, W. J., W.-S. Lee, G. J. Boer, V. V Kharin, J. F. Scinocca, G. M. Flato, R. S. Ajayamohan, J. C. Fyfe, Y. Tang, and S. Polavarapu, 2013: The Canadian Seasonal to Interannual Prediction System. Part I: Models and Initialization. Mon. Weather Rev., 141, 2910–2945, doi:10.1175/MWR-D-12-00216.1. Molteni, F., T. Stockdale, M. Balmaseda, G. Balsamo, R. Buizza, L. Ferranti, L. Magnusson, K. Mogensen, T. Palmer, and F. Vitart, 2011: The new ECMWF seasonal forecast system (System 4). Tech. Memo., 656, 1–49. Müller, W. A., C. Appenzeller, and C. Schär, 2005: Probabilistic seasonal prediction of the winter North Atlantic Oscillation and its impact on near surface temperature. Clim. Dyn., 24, 213–226, doi:10.1007/s00382-004-0492-z. National Research Council, 2010: Assessment of Intraseasonal to Interannual Climate Prediction and Predictability. The National Academies Press, Washington, DC,. Orsolini, Y. J., I. T. Kindem, and N. G. Kvamstø, 2009: On the potential impact of the stratosphere upon seasonal dynamical hindcasts of the North Atlantic Oscillation: a pilot study. Clim. Dyn., 36, 579–588, doi:10.1007/s00382-009-0705-6. Osprey, S. M., L. J. Gray, S. C. Hardiman, N. Butchart, and T. J. Hinton, 2013: Stratospheric Variability in Twentieth-Century CMIP5 Simulations of the Met Office Climate Model: High Top versus Low Top. J. Clim., 26, 1595–1606, doi:10.1175/JCLI-D-12-00147.1. Peng, P., A. Kumar, H. van den Dool, and A. G. Barnston, 2002: An analysis of multimodel ensemble predictions for seasonal climate anomalies. J. Geophys. Res. Atmos., 107, 4710, doi:10.1029/2002JD002712. Riddle, E. E., A. H. Butler, J. C. Furtado, J. L. Cohen, and A. Kumar, 2013: CFSv2 ensemble prediction of the wintertime Arctic Oscillation. Clim. Dyn., 41, 1099–1116. Roff, G., D. W. J. Thompson, and H. Hendon, 2011: Does increasing model stratospheric resolution improve extended-range forecast skill? Geophys. Res. Lett., 38, doi:10.1029/2010GL046515. Saha, S., S. Nadiga, C. Thiaw, J. Wang, W. Wang, Q. Zhang, H. M. Van den Dool, H.-L. Pan, S. Moorthi, D. Behringer, D. Stokes, M. Peña, S. Lord, G. White, W. Ebisuzaki, P. Peng, and P. Xie, 2006: The NCEP Climate Forecast System. J. Clim., 19, 3483–3517, doi:10.1175/JCLI3812.1. Von Salzen, K., J. F. Scinocca, N. A. McFarlane, J. Li, J. N. S. Cole, D. Plummer, D. Verseghy, M. C. Reader, X. Ma, M. Lazare, and L. Solheim, 2013: The Canadian Fourth Generation Atmospheric Global Climate Model (CanAM4). Part I: Representation of Physical Processes. Atmosphere-Ocean, 51, 104–125, doi:10.1080/07055900.2012.755610. Sato, K., and T. J. Dunkerton, 1997: Estimates of momentum flux associated with equatorial Kelvin and gravity waves. J. Geophys. Res. Atmos., 102, 26247–26261, doi:10.1029/96JD02514. Scaife, A. A., J. R. Knight, G. K. Vallis, and C. K. Folland, 2005: A stratospheric influence on the winter NAO and North Atlantic surface climate. Geophys. Res. Lett., 32, doi:10.1029/2005GL023226. ——, D. Copsey, C. Gordon, C. Harris, T. Hinton, S. Keeley, A. O’Neill, M. Roberts, and K. Williams, 2011: Improved Atlantic winter blocking in a climate model. Geophys. Res. Lett., 38, doi:10.1029/2011GL049573. ——, T. Spangehl, D. R. Fereday, U. Cubasch, U. Langematz, H. Akiyoshi, S. Bekki, P. Braesicke, N. Butchart, M. P. Chipperfield, A. Gettelman, S. C. Hardiman, M. Michou, E. Rozanov, and T. G. Shepherd, 2012: Climate change projections and stratosphere–troposphere interaction. Clim. Dyn., 38, 2089–2097, doi:10.1007/s00382-011-1080-7. Scaife, A. A., A. Arribas, E. Blockley, A. Brookshaw, R. T. Clark, N. Dunstone, R. Eade, D. Fereday, C. K. Folland, M. Gordon, L. Hermanson, J. R. Knight, D. J. Lea, C. MacLachlan, A. Maidens, M. Martin, A. K. Peterson, D. Smith, M. Vellinga, E. Wallace, J. Waters, and A. Williams, 2014a: Skillful long-range prediction of European and North American winters. Geophys. Res. Lett., 41, 2014GL059637, doi:10.1002/2014GL059637. Scaife, A. A., M. Athanassiadou, M. Andrews, A. Arribas, M. Baldwin, N. Dunstone, J. Knight, C. MacLachlan, E. Manzini, W. A. Müller, H. Pohlmann, D. Smith, T. Stockdale, and A. Williams, 2014b: Predictability of the Quasi-Biennial Oscillation and its Northern Winter Teleconnection on Seasonal to Decadal Timescales. Geophys. Res. Lett., 41, 1752–1758, doi:10.1002/2013GL059160. Scaife, A. A., A. Y. Karpechko, M. P. Baldwin, A. Brookshaw, A. H. Butler, R. Eade, M. Gordon, C. MacLachlan, N. Martin, N. Dunstone, and D. Smith, 2015: Seasonal winter forecasts and the stratosphere. Atmos. Sci. Lett., doi:10.1002/asl.598. Scinocca, J. F., N. A. McFarlane, M. Lazare, J. Li, and D. Plummer, 2008: Technical Note: The CCCma third generation AGCM and its extension into the middle atmosphere. Atmos. Chem. Phys., 8, 7055–7074, doi:10.5194/acp-8-7055-2008. Shaw, T. A., and J. Perlwitz, 2010: The Impact of Stratospheric Model Configuration on Planetary-Scale Waves in Northern Hemisphere Winter. J. Clim., 23, 3369–3389, doi:10.1175/2010JCLI3438.1. ——, ——, and O. Weiner, 2014: Troposphere-stratosphere coupling: Links to North Atlantic weather and climate, including their representation in CMIP5 models. J. Geophys. Res. Atmos., 2013JD021191, doi:10.1002/2013JD021191. Shi, W., N. Schaller, D. MacLeod, T. N. Palmer, and A. Weisheimer, 2015: Impact of hindcast length on estimates of seasonal climate predictability. Geophys. Res. Lett., 42, 1554–1559, doi:10.1002/2014GL062829. Sigmond, M., J. F. Scinocca, and P. J. Kushner, 2008: Impact of the stratosphere on tropospheric climate change. Geophys. Res. Lett., 35, doi:10.1029/2008GL033573. Sigmond, M., J. F. Scinocca, V. V. Kharin, and T. G. Shepherd, 2013: Enhanced seasonal forecast skill following stratospheric sudden warmings. Nat. Geosci., 6, 98–102, doi:10.1038/ngeo1698. Smith, D. M., A. A. Scaife, and B. P. Kirtman, 2012: What is the current state of scientific knowledge with regard to seasonal and decadal forecasting? Environ. Res. Lett., 7, 15602. Smith, K. L., C. G. Fletcher, and P. J. Kushner, 2010: The Role of Linear Interference in the Annular Mode Response to Extratropical Surface Forcing. J. Clim., 23, 6036–6050, doi:10.1175/2010JCLI3606.1. Stevens, B., M. Giorgetta, M. Esch, T. Mauritsen, T. Crueger, S. Rast, M. Salzmann, H. Schmidt, J. Bader, K. Block, R. Brokopf, I. Fast, S. Kinne, L. Kornblueh, U. Lohmann, R. Pincus, T. Reichler, and E. Roeckner, 2013: Atmospheric component of the MPI-M Earth System Model: ECHAM6. J. Adv. Model. Earth Syst., 5, 146–172, doi:10.1002/jame.20015. Stockdale, T. N., F. Molteni, and L. Ferranti, 2015: Atmospheric initial conditions and the predictability of the Arctic Oscillation. Geophys. Res. Lett., 42, 2014GL062681, doi:10.1002/2014GL062681. Takaya, Y., T. Yasuda, T. Ose, and T. Nakaegawa, 2010: Predictability of the Mean Location of Typhoon Formation in a Seasonal Prediction Experiment with a Coupled General Circulation Model. J. Meteorol. Soc. Japan, 88, 799–812, doi:10.2151/jmsj.2010-502. Toniazzo, T., and A. a. Scaife, 2006: The influence of ENSO on winter North Atlantic climate. Geophys. Res. Lett., 33, L24704, doi:10.1029/2006GL027881. Tripathi, O. P., M. Baldwin, A. Charlton-Perez, M. Charron, S. D. Eckermann, E. Gerber, R. G. Harrison, D. R. Jackson, B.-M. Kim, Y. Kuroda, A. Lang, S. Mahmood, R. Mizuta, G. Roff, M. Sigmond, and S.-W. Son, 2014: The predictability of the extratropical stratosphere on monthly time-scales and its impact on the skill of tropospheric forecasts. Q. J. R. Meteorol. Soc., doi:10.1002/qj.2432. ——, A. Charlton-Perez, M. Sigmond, and F. Vitart, 2015: Enhanced long-range forecast skill in boreal winter following stratospheric strong vortex conditions. Environ. Res. Lett., 10, 104007. Voldoire, A., E. Sánchez Gómez, D. Salas y Mélia, B. Decharme, C. Cassou, S. Sénési, S. Valcke, I. Beau, A. Alias, M. Chevallier, M. Déqué, J. Deshayes, H. Douville, E. Fernández, G. Madec, E. Maisonnave, M.-P. Moine, S. Planton, D. Saint-Martin, S. Szopa, S. Tyteca, R. Alkama, S. Belamari, A. Braun, L. Coquart, and F. Chauvin, 2013: The CNRM-CM5.1 global climate model: description and basic evaluation. Clim. Dyn., 40, 2091–2121, doi:10.1007/s00382-011-1259-y. Watanabe, M., T. Suzuki, R. O’ishi, Y. Komuro, S. Watanabe, S. Emori, T. Takemura, M. Chikira, T. Ogura, M. Sekiguchi, K. Takata, D. Yamazaki, T. Yokohata, T. Nozawa, H. Hasumi, H. Tatebe, and M. Kimoto, 2010: Improved Climate Simulation by MIROC5: Mean States, Variability, and Climate Sensitivity. J. Clim., 23, 6312–6335, doi:10.1175/2010JCLI3679.1.