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51. Consequences of future increased Arctic runoff on Arctic Ocean stratification, circulation, and sea ice cover

Author

Mehmet Ilicak, Camille Li, Aleksi Nummelin, and Lars Henrik Smedsrud

Subjects
Arctic sea ice decline, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Arctic dipole anomaly, 010505 oceanography, Ocean current, Physical oceanography, Oceanography, 01 natural sciences, Arctic geoengineering, Geophysics, Arctic, Space and Planetary Science, Geochemistry and Petrology, Climatology, Earth and Planetary Sciences (miscellaneous), Sea ice, Environmental science, Thermohaline circulation, 0105 earth and related environmental sciences
Abstract

The Arctic Ocean has important freshwater sources including river runoff, low evaporation, and exchange with the Pacific Ocean. In the future, we expect even larger freshwater input as the global hydrological cycle accelerates, increasing high-latitude precipitation, and river runoff. Previous modeling studies show some robust responses to high-latitude freshwater perturbations, including a strengthening of Arctic stratification and a weakening of the large-scale ocean circulation; some idealized modeling studies also document a stronger cyclonic circulation within the Arctic Ocean itself. With the broad range of scales and processes involved, the overall effect of increasing runoff requires an understanding of both the local processes and the broader linkages between the Arctic and surrounding oceans. Here we adopt a more comprehensive modeling approach by increasing river runoff to the Arctic Ocean in a coupled ice-ocean general circulation model, and show contrasting responses in the polar and subpolar regions. Within the Arctic, the stratification strengthens, the halocline and Atlantic Water layer warm, and the cyclonic circulation spins up, in agreement with previous work. In the subpolar North Atlantic, the model simulates a colder and fresher water column with weaker barotropic circulation. In contrast to the estuarine circulation theory, the volume exchange between the Arctic Ocean and the surrounding oceans does not increase with increasing runoff. While these results are robust in our model, we require experiments with other model systems and more complete observational syntheses to better constrain the sensitivity of the climate system to high-latitude freshwater perturbations. publishedVersion

Published
2016

52. North Atlantic simulations in Coordinated Ocean-ice Reference Experiments phase II (CORE-II). Part II: Inter-annual to decadal variability

Author

Patrick Heimbach, Aurore Voldoire, Anatoly Gusev, Alicia Karspeck, Eric P. Chassignet, Rainer Bleck, Dmitry Sidorenko, Alexandra Bozec, David Salas y Mélia, Anastasia Romanou, Who M. Kim, Gael Forget, Daohua Bi, Vittorio Canuto, Simon J. Marsland, Gokhan Danabasoglu, Simona Masina, Hiroyuki Tsujino, Stephen M. Griffies, Sophie Valcke, Jianhua Lu, Mats Bentsen, Claus W. Böning, Pier Giuseppe Fogli, Gurvan Madec, Anthony Leboissetier, Mehmet Ilicak, Anna Pirani, Thomas Jung, Igor Yashayaev, Andrew C. Coward, Maxwell Kelley, Shan Sun, Yosuke Fujii, A. J. George Nurser, Petteri Uotila, Sergey Danilov, Elodie Fernandez, Steve G. Yeager, Christophe Cassou, Nikolay Diansky, A. M. Howard, William G. Large, Helge Drange, Anne-Marie Tréguier, Bonita L. Samuels, Erik Behrens, Qiang Wang, Arne Biastoch, Riccardo Farneti, Markus Scheinert, Antonio Navarra, National Center for Atmospheric Research [Boulder] (NCAR), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Uni Research Climate, Uni Research Ltd, Centre for Australian Weather and Climate Research (CAWCR), NASA Goddard Institute for Space Studies (GISS), NASA Goddard Space Flight Center (GSFC), Center for Ocean-Atmospheric Prediction Studies (COAPS), Florida State University [Tallahassee] (FSU), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), National Oceanography Centre (NOC), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Institute of Numerical Mathematics [Moscou] (INM-RAS), Russian Academy of Sciences [Moscow] (RAS), University of Bergen (UiB), Abdus Salam International Centre for Theoretical Physics [Trieste] (ICTP), Centro Euro-Mediterraneo per i Cambiamenti Climatici [Bologna] (CMCC), Massachusetts Institute of Technology (MIT), Meteorological Research Institute [Tsukuba] (MRI), Japan Meteorological Agency (JMA), NOAA Geophysical Fluid Dynamics Laboratory (GFDL), National Oceanic and Atmospheric Administration (NOAA), Pacific Northwest National Laboratory (PNNL), Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Matematica e Informatica [Perugia] (DMI), Università degli Studi di Perugia = University of Perugia (UNIPG), National Oceanography Centre [Southampton] (NOC), University of Southampton, International CLIVAR, Princeton University, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Biomedical Research Imaging Center [North Carolina] (BRIC), University of North Carolina [Chapel Hill] (UNC), University of North Carolina System (UNC)-University of North Carolina System (UNC), Danabasoglu G, Yeager SG, Kim WM, Behrens E, Bentsen M, Bi DH, Biastoch A, Bleck R, Boning C, Bozec A, Canuto VM, Cassou C, Chassignet E, Coward AC, Danilov S, Diansky N, Drange H, Farneti R, Fernandez E, Fogli PG, Forget G, Fujii Y, Griffies SM, Gusev A, Heimbach P, Howard A, Ilicak M, Jung T, Karspeck AR, Kelley M, Large WG, Leboissetier A, Lu JH, Madec G, Marsland SJ, Masina S, Navarra A, Nurser AJG, Pirani A, Romanou A, Melia DSY, Samuels BL, Scheinert M, Sidorenko D, Sun S, Treguier AM, Tsujino H, Uotila P, Valcke S, Voldoire A, Wang Q, Yashayaev I, CERFACS [Toulouse], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Università degli Studi di Perugia (UNIPG), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), and CERFACS

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Mixed layer, Phase (waves), [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Oceanography, 01 natural sciences, Ocean model comparisons, Computer Science (miscellaneous), 14. Life underwater, Atmospheric forcing, Variability in the North Atlantic, 0105 earth and related environmental sciences, Inter-annual to decadal variability and mechanisms, Atlantic meridional overturning circulation variability, 010505 oceanography, Global ocean - sea-ice modelling, Geotechnical Engineering and Engineering Geology, Deep water, Ocean dynamics, Marine Sciences, Sea surface temperature, 13. Climate action, North Atlantic oscillation, Climatology, Global ocean – sea-ice modelling, Ocean model comparisons, Atmospheric forcing, Hydrography, Global ocean – sea-ice modelling, Geology
Abstract

Simulated inter-annual to decadal variability and trends in the North Atlantic for the 1958-2007 period from twenty global ocean - sea-ice coupled models are presented. These simulations are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The study is Part II of our companion paper (Danabasoglu et al., 2014) which documented the mean states in the North Atlantic from the same models. A major focus of the present study is the representation of Atlantic meridional overturning circulation (AMOC) variability in the participating models. Relationships between AMOC variability and those of some other related variables, such as subpolar mixed layer depths, the North Atlantic Oscillation (NAO), and the Labrador Sea upper-ocean hydrographic properties, are also investigated. In general, AMOC variability shows three distinct stages. During the first stage that lasts until the mid-to late-1970s, AMOC is relatively steady, remaining lower than its long-term (1958-2007) mean. Thereafter, AMOC intensifies with maximum transports achieved in the mid-to late-1990s. This enhancement is then followed by a weakening trend until the end of our integration period. This sequence of low frequency AMOC variability is consistent with previous studies. Regarding strengthening of AMOC between about the mid-1970s and the mid-1990s, our results support a previously identified variability mechanism where AMOC intensification is connected to increased deep water formation in the subpolar North Atlantic, driven by NAO-related surface fluxes. The simulations tend to show general agreement in their temporal representations of, for example, AMOC, sea surface temperature (SST), and subpolar mixed layer depth variabilities. In particular, the observed variability of the North Atlantic SSTs is captured well by all models. These findings indicate that simulated variability and trends are primarily dictated by the atmospheric datasets which include the influence of ocean dynamics from nature superimposed onto anthropogenic effects. Despite these general agreements, there are many differences among the model solutions, particularly in the spatial structures of variability patterns. For example, the location of the maximum AMOC variability differs among the models between Northern and Southern Hemispheres. (C) 2015 Elsevier Ltd. All rights reserved.

Published
2016
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53. An assessment of global and regional sea level for years 1993-2007 in a suite of interannual CORE-II simulations

Author

Sophie Valcke, David M. Holland, Michael Winton, Xuebin Zhang, David Salas y Mélia, Gokhan Danabasoglu, Mats Bentsen, Sergey Danilov, Richard J. Greatbatch, Eric P. Chassignet, William G. Large, Hiroyuki Tsujino, Jianhua Lu, Stephen M. Griffies, Paul Goddard, A. J. George Nurser, Jens Schröter, Daohua Bi, Riccardo Farneti, Simon J. Marsland, Jianjun Yin, Petteri Uotila, Helge Drange, Anne-Marie Tréguier, Akhilesh Mishra, Katja Lorbacher, Bonita L. Samuels, Erik Behrens, Qiang Wang, Arne Biastoch, Catia M. Domingues, Aurore Voldoire, Yu-Heng Tseng, Paul J. Durack, Mehmet Ilicak, Franziska U. Schwarzkopf, Dmitry Sidorenko, Alexandra Bozec, Susan C. Bates, Jaime B. Palter, Elodie Fernandez, Claus W. Böning, NOAA Geophysical Fluid Dynamics Laboratory ( GFDL ), National Oceanic and Atmospheric Administration ( NOAA ), Department of Geosciences, University of Arizona, Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, National Center for Atmospheric Research [Boulder] ( NCAR ), GEOMAR - Helmholtz Centre for Ocean Research [Kiel] ( GEOMAR ), Uni Research Climate, Uni Research Ltd, Center for Australian Weather and Climate Research, Bureau of Meteorolgy, Center for Acean-Atmospheric Prediction Studies ( COAPS ), Florida State University, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung ( AWI ), University of Bergen ( UIB ), International Centre for Theoretical Physics, Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique ( CERFACS ), CERFACS, New York University [New York], National Oceanography Centre [Southampton] ( NOC ), University of Southampton [Southampton], Groupe d'étude de l'atmosphère météorologique ( CNRM-GAME ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Météo France-Centre National de la Recherche Scientifique ( CNRS ), McGill University, Laboratoire de physique des océans ( LPO ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ), Meteorological Research Institute [Tsukuba] ( MRI ), Japan Meteorological Agency ( JMA ), CSIRO Marine and Atmospheric Research ( CSIRO ), Commonwealth Scientific and Industrial Research Organisation [Canberra] ( CSIRO ), NOAA Geophysical Fluid Dynamics Laboratory (GFDL), National Oceanic and Atmospheric Administration (NOAA), Department of Geosciences [Tucson], Lawrence Livermore National Laboratory (LLNL), National Center for Atmospheric Research [Boulder] (NCAR), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Centre for Australian Weather and Climate Research (CAWCR), Center for Ocean-Atmospheric Prediction Studies (COAPS), Florida State University [Tallahassee] (FSU), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), University of Bergen (UiB), Abdus Salam International Centre for Theoretical Physics [Trieste] (ICTP), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), New York University [New York] (NYU), NYU System (NYU), National Oceanography Centre [Southampton] (NOC), University of Southampton, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), McGill University = Université McGill [Montréal, Canada], Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Meteorological Research Institute [Tsukuba] (MRI), Japan Meteorological Agency (JMA), CSIRO Marine and Atmospheric Research (CSIRO), and Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO)

Subjects
Arctic sea ice decline, Atmospheric Science, 010504 meteorology & atmospheric sciences, Oceanography, 01 natural sciences, CORE global ocean-ice simulations, Ocean gyre, Steric sea level, Computer Science (miscellaneous), Sea level, 14. Life underwater, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Momentum (technical analysis), geography, geography.geographical_feature_category, [ SDU.STU.OC ] Sciences of the Universe [physics]/Earth Sciences/Oceanography, 010505 oceanography, Advection, Global sea level, Geotechnical Engineering and Engineering Geology, Ocean heat content, 13. Climate action, North Atlantic oscillation, Climatology, Environmental science, Thermohaline circulation
Abstract

Highlights: • Global mean sea level simulated in interannual CORE simulations. • Regional sea level patterns simulated in interannual CORE simulations. • Theoretical foundation for analysis of global mean sea level and regional patterns. Abstract: We provide an assessment of sea level simulated in a suite of global ocean-sea ice models using the interannual CORE atmospheric state to determine surface ocean boundary buoyancy and momentum fluxes. These CORE-II simulations are compared amongst themselves as well as to observation-based estimates. We focus on the final 15 years of the simulations (1993–2007), as this is a period where the CORE-II atmospheric state is well sampled, and it allows us to compare sea level related fields to both satellite and in situ analyses. The ensemble mean of the CORE-II simulations broadly agree with various global and regional observation-based analyses during this period, though with the global mean thermosteric sea level rise biased low relative to observation-based analyses. The simulations reveal a positive trend in dynamic sea level in the west Pacific and negative trend in the east, with this trend arising from wind shifts and regional changes in upper 700 m ocean heat content. The models also exhibit a thermosteric sea level rise in the subpolar North Atlantic associated with a transition around 1995/1996 of the North Atlantic Oscillation to its negative phase, and the advection of warm subtropical waters into the subpolar gyre. Sea level trends are predominantly associated with steric trends, with thermosteric effects generally far larger than halosteric effects, except in the Arctic and North Atlantic. There is a general anti-correlation between thermosteric and halosteric effects for much of the World Ocean, associated with density compensated changes.

Published
2014
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54. Non-Hydrostatic Modeling Of Exchange Flows Across Complex Geometries

Author

Paul Fischer, Mehmet Ilicak, Emin Özsoy, and Tamay M. Özgökmen

Subjects
Atmospheric Science, Meteorology, Turbulence, Time evolution, Mechanics, Internal wave, Geotechnical Engineering and Engineering Geology, Oceanography, Potential energy, Eddy, Closure (computer programming), Inviscid flow, Computer Science (miscellaneous), Geology, Large eddy simulation
Abstract

Flows between ocean and marginal sea basins are often connected by narrow channels and shallow sills. In this study, we address the effect of lateral and vertical geometric constrictions on mixing and hydraulic control. We conduct a set of numerical experiments of the lock-exchange problem in the presence of lateral and vertical contractions. Large eddy simulations (LES) are carried out using the high-order nonhydrostatic spectral element model Nek5000. A spanwise-averaged 2D non-hydrostatic model, denoted SAM, is also employed. Comparison between 2D and 3D models are conducted on the basis of the shape of the density interface and the time evolution of the background potential energy that quantifies the cumulative effects of the stratified mixing in the system. LES indicates that an S-shaped channel induces the highest amount of mixing possibly due to the additional shears caused by the centrifugal force. Vertical and horizontal constrictions enhance mixing by the trapping and breaking of the internal waves in between the obstacles. On the other hand, vertical and horizontal constrictions overlapping with each other restrain the rate of the exchange flow, reduce vertical shears and the mixing. The lowest mixing is encountered in a W -shaped channel. It is also found that SAM appears to be accurate in identifying the hydraulic control points due to both horizontal and vertical constrictions. A good agreement is found between SAM and inviscid two-layer theory regarding the steady-state location of the density interface. However SAM overestimates mixing with respect to LES since overturning eddies tend to merge in 2D, while they break down into smaller scales in 3D. SAM is then further tested a realistic application to model the flow in the Bosphorus Strait. Here, the main challenges of using SAM revolved around a non-trivial reduction of 3D geometry to a 2D mapping function, and excessive diffusion with simple closures. The realism of SAM improves significantly using a comprehensive turbulence closure of Very Large Eddy Simulation, VLES. In conclusion, exchange flows in narrow straits pose significant computational challenges due to the details of domain geometry and their impact on mixing. SAM with the VLES turbulence closure appears to be an attractive modeling tool for a first-order assessment of dynamical problems involving mixing

Published
2009

55. Variability along the Atlantic water pathway in the forced Norwegian Earth System Model

Author

Mehmet Ilicak, Anne Britt Sandø, Marius Årthun, and Helene R. Langehaug

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Subpolar North Atlantic, Anomaly (natural sciences), Ocean current, Temperature salinity diagrams, Norwegian, 010502 geochemistry & geophysics, Nordic seas, 01 natural sciences, Thermohaline anomalies, Atlantic water, language.human_language, Subpolar Gyre, 13. Climate action, Climatology, NorESM, language, Climate model, Thermohaline circulation, Predictability, Geology, 0105 earth and related environmental sciences
Abstract

The growing attention on mechanisms that can provide predictability on interannual-to-decadal time scales, makes it necessary to identify how well climate models represent such mechanisms. In this study we use a high (0.25° horizontal grid) and a medium (1°) resolution version of a forced global ocean-sea ice model, utilising the Norwegian Earth System Model, to assess the impact of increased ocean resolution. Our target is the simulation of temperature and salinity anomalies along the pathway of warm Atlantic water in the subpolar North Atlantic and the Nordic Seas. Although the high resolution version has larger biases in general at the ocean surface, the poleward propagation of thermohaline anomalies is better resolved in this version, i.e., the time for an anomaly to travel northward is more similar to observation based estimates. The extent of these anomalies can be rather large in both model versions, as also seen in observations, e.g., stretching from Scotland to northern Norway. The easternmost branch into the Nordic and Barents Seas, carrying warm Atlantic water, is also improved by higher resolution, both in terms of mean heat transport and variability in thermohaline properties. A more detailed assessment of the link between the North Atlantic Ocean circulation and the thermohaline anomalies at the entrance of the Nordic Seas reveals that the high resolution is more consistent with mechanisms that are previously published. This suggests better dynamics and variability in the subpolar region and the Nordic Seas in the high resolution compared to the medium resolution. This is most likely due a better representation of the mean circulation in the studied region when using higher resolution. As the poleward propagation of ocean heat anomalies is considered to be a key source of climate predictability, we recommend that similar methodology presented herein should be performed oncoupledclimate models that are used for climate prediction.

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