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  • 1. Akperov, Mirseid
    et al.
    Rinke, Annette
    Mokhov, Igor I.
    Matthes, Heidrun
    Semenov, Vladimir A.
    Adakudlu, Muralidhar
    Cassano, John
    Christensen, Jens H.
    Dembitskaya, Mariya A.
    Dethloff, Klaus
    Fettweis, Xavier
    Glisan, Justin
    Gutjahr, Oliver
    Heinemann, Guenther
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koldunov, Nikolay V.
    Laprise, Rene
    Mottram, Ruth
    Nikiema, Oumarou
    Scinocca, John F.
    Sein, Dmitry
    Sobolowski, Stefan
    Winger, Katja
    Zhang, Wenxin
    Cyclone Activity in the Arctic From an Ensemble of Regional Climate Models (Arctic CORDEX)2018Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 123, nr 5, s. 2537-2554Artikel i tidskrift (Refereegranskat)
  • 2. Akperov, Mirseid
    et al.
    Rinke, Annette
    Mokhov, Igor I.
    Semenov, Vladimir A.
    Parfenova, Mariya R.
    Matthes, Heidrun
    Adakudlu, Muralidhar
    Boberg, Fredrik
    Christensen, Jens H.
    Dembitskaya, Mariya A.
    Dethloff, Klaus
    Fettweis, Xavier
    Gutjahr, Oliver
    Heinemann, Gunther
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koldunov, Nikolay, V
    Laprise, Rene
    Mottram, Ruth
    Nikiema, Oumarou
    Sein, Dmitry
    Sobolowski, Stefan
    Winger, Katja
    Zhang, Wenxin
    Future projections of cyclone activity in the Arctic for the 21st century from regional climate models (Arctic-CORDEX)2019Ingår i: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 182, artikel-id UNSP 103005Artikel i tidskrift (Refereegranskat)
  • 3. Bellucci, A.
    et al.
    Haarsma, R.
    Bellouin, N.
    Booth, B.
    Cagnazzo, C.
    van den Hurk, B.
    Keenlyside, N.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Massonnet, F.
    Materia, S.
    Weiss, M.
    Advancements in decadal climate predictability: The role of nonoceanic drivers2015Ingår i: Reviews of geophysics, ISSN 8755-1209, E-ISSN 1944-9208, Vol. 53, nr 2, s. 165-202Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We review recent progress in understanding the role of sea ice, land surface, stratosphere, and aerosols in decadal-scale predictability and discuss the perspectives for improving the predictive capabilities of current Earth system models (ESMs). These constituents have received relatively little attention because their contribution to the slow climatic manifold is controversial in comparison to that of the large heat capacity of the oceans. Furthermore, their initialization as well as their representation in state-of-the-art climate models remains a challenge. Numerous extraoceanic processes that could be active over the decadal range are proposed. Potential predictability associated with the aforementioned, poorly represented, and scarcely observed constituents of the climate system has been primarily inspected through numerical simulations performed under idealized experimental settings. The impact, however, on practical decadal predictions, conducted with realistically initialized full-fledged climate models, is still largely unexploited. Enhancing initial-value predictability through an improved model initialization appears to be a viable option for land surface, sea ice, and, marginally, the stratosphere. Similarly, capturing future aerosol emission storylines might lead to an improved representation of both global and regional short-term climatic changes. In addition to these factors, a key role on the overall predictive ability of ESMs is expected to be played by an accurate representation of processes associated with specific components of the climate system. These act as signal carriers, transferring across the climatic phase space the information associated with the initial state and boundary forcings, and dynamically bridging different (otherwise unconnected) subsystems. Through this mechanism, Earth system components trigger low-frequency variability modes, thus extending the predictability beyond the seasonal scale.

  • 4.
    Berg, Peter
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Impacts of using spectral nudging on regional climate model RCA4 simulations of the Arctic2013Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 6, nr 3, s. 849-859Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of the Rossby Centre regional climate model RCA4 is investigated for the Arctic CORDEX (COordinated Regional climate Downscaling EXperiment) region, with an emphasis on its suitability to be coupled to a regional ocean and sea ice model. Large biases in mean sea level pressure (MSLP) are identified, with pronounced too-high pressure centred over the North Pole in summer of over 5 hPa, and too-low pressure in winter of a similar magnitude. These lead to biases in the surface winds, which will potentially lead to strong sea ice biases in a future coupled system. The large-scale circulation is believed to be the major reason for the biases, and an implementation of spectral nudging is applied to remedy the problems by constraining the large-scale components of the driving fields within the interior domain. It is found that the spectral nudging generally corrects for the MSLP and wind biases, while not significantly affecting other variables, such as surface radiative components, two-metre temperature and precipitation.

  • 5.
    Berg, Peter
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    On the effects of constraining atmospheric circulation in a coupled atmosphere-ocean Arctic regional climate model2016Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, nr 11-12, s. 3499-3515Artikel i tidskrift (Refereegranskat)
  • 6. Brodeau, Laurent
    et al.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Extinction of the northern oceanic deep convection in an ensemble of climate model simulations of the 20th and 21st centuries2016Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, nr 9-10, s. 2863-2882Artikel i tidskrift (Refereegranskat)
  • 7.
    Caian, Mihaela
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Devasthale, Abhay
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation2018Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 50, nr 1-2, s. 423-441Artikel i tidskrift (Refereegranskat)
  • 8.
    Caian, Mihaela
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Devasthale, Abhay
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation (vol 50, pg 423, 2017)2018Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 50, nr 1-2, s. 443-443Artikel i tidskrift (Refereegranskat)
  • 9.
    Devasthale, Abhay
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Sedlar, Joseph
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Fetzer, E. J.
    The thermodynamic state of the Arctic atmosphere observed by AIRS: comparisons during the record minimum sea ice extents of 2007 and 20122013Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 13, nr 15, s. 7441-7450Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The record sea ice minimum (SIM) extents observed during the summers of 2007 and 2012 in the Arctic are stark evidence of accelerated sea ice loss during the last decade. Improving our understanding of the Arctic atmosphere and accurate quantification of its characteristics becomes ever more crucial, not least to improve predictions of such extreme events in the future. In this context, the Atmospheric Infrared Sounder (AIRS) instrument onboard NASA's Aqua satellite provides crucial insights due to its ability to provide 3-D information on atmospheric thermodynamics. Here, we facilitate comparisons in the evolution of the thermodynamic state of the Arctic atmosphere during these two SIM events using a decade-long AIRS observational record (2003-2012). It is shown that the meteorological conditions during 2012 were not extreme, but three factors of preconditioning from winter through early summer played an important role in accelerating sea ice melt. First, the marginal sea ice zones along the central Eurasian and North Atlantic sectors remained warm throughout winter and early spring in 2012 preventing thicker ice build-up. Second, the circulation pattern favoured efficient sea ice transport out of the Arctic in the Atlantic sector during late spring and early summer in 2012 compared to 2007. Third, additional warming over the Canadian archipelago and southeast Beaufort Sea from May onward further contributed to accelerated sea ice melt. All these factors may have lead the already thin and declining sea ice cover to pass below the previous sea ice extent minimum of 2007. In sharp contrast to 2007, negative surface temperature anomalies and increased cloudiness were observed over the East Siberian and Chukchi seas in the summer of 2012. The results suggest that satellite-based monitoring of atmospheric preconditioning could be a critical source of information in predicting extreme sea ice melting events in the Arctic.

  • 10.
    Doescher, Ralf
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Arctic rapid sea ice loss events in regional coupled climate scenario experiments2013Ingår i: Ocean Science, ISSN 1812-0784, E-ISSN 1812-0792, Vol. 9, nr 2, s. 217-248Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rapid sea ice loss events (RILEs) in a mini-ensemble of regional Arctic coupled climate model scenario experiments are analyzed. Mechanisms of sudden ice loss are strongly related to atmospheric circulation conditions and preconditioning by sea ice thinning during the seasons and years before the event. Clustering of events in time suggests a strong control by large-scale atmospheric circulation. Anomalous atmospheric circulation is providing warm air anomalies of up to 5 K and is forcing ice flow, affecting winter ice growth. Even without a seasonal preconditioning during winter, ice drop events can be initiated by anomalous inflow of warm air during summer. It is shown that RILEs can be generated based on atmospheric circulation changes as a major driving force without major competing mechanisms, other than occasional longwave effects during spring and summer. Other anomalous seasonal radiative forcing or short-lived forcers (e.g., soot) play minor roles or no role at all in our model. RILEs initiated by ocean forcing do not occur in the model, although cannot be ruled out due to model limitations. Mechanisms found are qualitatively in line with observations of the 2007 RILE.

  • 11.
    Fuentes Franco, Ramon
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Sensitivity of the Arctic freshwater content and transport to model resolution2019Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 53, nr 3-4, s. 1765-1781Artikel i tidskrift (Refereegranskat)
  • 12. Grist, Jeremy P.
    et al.
    Josey, Simon A.
    New, Adrian L.
    Roberts, Malcolm
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Iovino, Doroteaciro
    Increasing Atlantic Ocean Heat Transport in the Latest Generation Coupled Ocean-Atmosphere Models: The Role of Air-Sea Interaction2018Ingår i: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 123, nr 11, s. 8624-8637Artikel i tidskrift (Refereegranskat)
  • 13. Guemas, Virginie
    et al.
    Blanchard-Wrigglesworth, Edward
    Chevallier, Matthieu
    Day, Jonathan J.
    Deque, Michel
    Doblas-Reyes, Francisco J.
    Fuckar, Neven S.
    Germe, Agathe
    Hawkins, Ed
    Keeley, Sarah
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Salas y Melia, David
    Tietsche, Steffen
    A review on Arctic sea-ice predictability and prediction on seasonal to decadal time-scales2016Ingår i: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 142, nr 695, s. 546-561Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sea ice plays a crucial role in the Earth's energy and water budget and has a substantial impact on local and remote atmospheric and oceanic circulations. Predictions of Arctic sea-ice conditions a few months to a few years in advance could be of interest for stakeholders. This article presents a review of the potential sources of Arctic sea-ice predictability on these time-scales. Predictability mainly originates from persistence or advection of sea-ice anomalies, interactions with the ocean and atmosphere and changes in radiative forcing. After estimating the inherent potential predictability limit with state-of-the-art models, current sea-ice forecast systems are described, together with their performance. Finally, some challenges and issues in sea-ice forecasting are presented, along with suggestions for future research priorities.

  • 14. Haarsma, Reindert J.
    et al.
    Roberts, Malcolm J.
    Vidale, Pier Luigi
    Senior, Catherine A.
    Bellucci, Alessio
    Bao, Qing
    Chang, Ping
    Corti, Susanna
    Fuckar, Neven S.
    Guemas, Virginie
    von Hardenberg, Jost
    Hazeleger, Wilco
    Kodama, Chihiro
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Leung, L. Ruby
    Lu, Jian
    Luo, Jing-Jia
    Mao, Jiafu
    Mizielinski, Matthew S.
    Mizuta, Ryo
    Nobre, Paulo
    Satoh, Masaki
    Scoccimarro, Enrico
    Semmler, Tido
    Small, Justin
    von Storch, Jin-Song
    High Resolution Model Intercomparison Project (HighResMIP v1.0) for CMIP62016Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 9, nr 11, s. 4185-4208Artikel i tidskrift (Refereegranskat)
  • 15. Hazeleger, Wilco
    et al.
    Severijns, Camiel
    Semmler, Tido
    Stefanescu, Simona
    Yang, Shuting
    Wang, Xueli
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Dutra, Emanuel
    Baldasano, Jose M.
    Bintanja, Richard
    Bougeault, Philippe
    Caballero, Rodrigo
    Ekman, Annica M. L.
    Christensen, Jens H.
    van den Hurk, Bart
    Jimenez, Pedro
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kållberg, Per
    SMHI, Forskningsavdelningen, Meteorologi.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    McGrath, Ray
    Miranda, Pedro
    Van Noije, Twan
    Palmer, Tim
    Parodi, Jose A.
    Schmith, Torben
    Selten, Frank
    Storelvmo, Trude
    Sterl, Andreas
    Tapamo, Honore
    Vancoppenolle, Martin
    Viterbo, Pedro
    Willén, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    EC-Earth A Seamless Earth-System Prediction Approach in Action2010Ingår i: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 91, nr 10, s. 1357-1363Artikel i tidskrift (Övrigt vetenskapligt)
  • 16. Jung, Thomas
    et al.
    Doblas-Reyes, Francisco
    Goessling, Helge
    Guemas, Virginie
    Bitz, Cecilia
    Buontempo, Carlo
    Caballero, Rodrigo
    Jakobson, Erko
    Jungclaus, Johann
    Karcher, Michael
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Matei, Daniela
    Overland, James
    Spengler, Thomas
    Yang, Shuting
    POLAR LOWER-LATITUDE LINKAGES AND THEIR ROLE IN WEATHER AND CLIMATE PREDICTION2015Ingår i: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 96, nr 11, s. ES197-ES200Artikel i tidskrift (Refereegranskat)
  • 17. Jungclaus, Johann H.
    et al.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Low-frequency variability of the arctic climate: the role of oceanic and atmospheric heat transport variations2010Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 34, nr 2-3, s. 265-279Artikel i tidskrift (Refereegranskat)
  • 18.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Beatty, Christof Konig
    Caian, Mihaela
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Potential decadal predictability and its sensitivity to sea ice albedo parameterization in a global coupled model2012Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 38, nr 11-12, s. 2389-2408Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Decadal prediction is one focus of the upcoming 5th IPCC Assessment report. To be able to interpret the results and to further improve the decadal predictions it is important to investigate the potential predictability in the participating climate models. This study analyzes the upper limit of climate predictability on decadal time scales and its dependency on sea ice albedo parameterization by performing two perfect ensemble experiments with the global coupled climate model EC-Earth. In the first experiment, the standard albedo formulation of EC-Earth is used, in the second experiment sea ice albedo is reduced. The potential prognostic predictability is analyzed for a set of oceanic and atmospheric parameters. The decadal predictability of the atmospheric circulation is small. The highest potential predictability was found in air temperature at 2 m height over the northern North Atlantic and the southern South Atlantic. Over land, only a few areas are significantly predictable. The predictability for continental size averages of air temperature is relatively good in all northern hemisphere regions. Sea ice thickness is highly predictable along the ice edges in the North Atlantic Arctic Sector. The meridional overturning circulation is highly predictable in both experiments and governs most of the decadal climate predictability in the northern hemisphere. The experiments using reduced sea ice albedo show some important differences like a generally higher predictability of atmospheric variables in the Arctic or higher predictability of air temperature in Europe. Furthermore, decadal variations are substantially smaller in the simulations with reduced ice albedo, which can be explained by reduced sea ice thickness in these simulations.

  • 19.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Berg, Peter
    SMHI, Forskningsavdelningen, Hydrologi.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Arctic climate change in an ensemble of regional CORDEX simulations2015Ingår i: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 34, artikel-id 24603Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fifth phase Climate Model Intercomparison Project historical and scenario simulations from four global climate models (GCMs) using the Representative Concentration Pathways greenhouse gas concentration trajectories RCP4.5 and RCP8.5 are downscaled over the Arctic with the regional Rossby Centre Atmosphere model (RCA). The regional model simulations largely reflect the circulation bias patterns of the driving global models in the historical period, indicating the importance of lateral and lower boundary conditions. However, local differences occur as a reduced winter 2-m air temperature bias over the Arctic Ocean and increased cold biases over land areas in RCA. The projected changes are dominated by a strong warming in the Arctic, exceeding 15 degrees K in autumn and winter over the Arctic Ocean in RCP8.5, strongly increased precipitation and reduced sea-level pressure. Near-surface temperature and precipitation are linearly related in the Arctic. The wintertime inversion strength is reduced, leading to a less stable stratification of the Arctic atmosphere. The diurnal temperature range is reduced in all seasons. The large-scale change patterns are dominated by the surface and lateral boundary conditions so future response is similar in RCA and the driving global models. However, the warming over the Arctic Ocean is smaller in RCA; the warming over land is larger in winter and spring but smaller in summer. The future response of winter cloud cover is opposite in RCA and the GCMs. Precipitation changes in RCA are much larger during summer than in the global models and more small-scale change patterns occur.

  • 20.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Brodeau, Laurent
    Arctic climate and its interaction with lower latitudes under different levels of anthropogenic warming in a global coupled climate model2017Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 49, nr 1-2, s. 471-492Artikel i tidskrift (Refereegranskat)
  • 21.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Brodeau, Laurent
    Ocean heat transport into the Arctic in the twentieth and twenty-first century in EC-Earth2014Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 42, nr 11-12, s. 3101-3120Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ocean heat transport into the Arctic and the heat budget of the Barents Sea are analyzed in an ensemble of historical and future climate simulations performed with the global coupled climate model EC-Earth. The zonally integrated northward heat flux in the ocean at 70A degrees N is strongly enhanced and compensates for a reduction of its atmospheric counterpart in the twenty first century. Although an increase in the northward heat transport occurs through all of Fram Strait, Canadian Archipelago, Bering Strait and Barents Sea Opening, it is the latter which dominates the increase in ocean heat transport into the Arctic. Increased temperature of the northward transported Atlantic water masses are the main reason for the enhancement of the ocean heat transport. The natural variability in the heat transport into the Barents Sea is caused to the same extent by variations in temperature and volume transport. Large ocean heat transports lead to reduced ice and higher atmospheric temperature in the Barents Sea area and are related to the positive phase of the North Atlantic Oscillation. The net ocean heat transport into the Barents Sea grows until about year 2050. Thereafter, both heat and volume fluxes out of the Barents Sea through the section between Franz Josef Land and Novaya Zemlya are strongly enhanced and compensate for all further increase in the inflow through the Barents Sea Opening. Most of the heat transported by the ocean into the Barents Sea is passed to the atmosphere and contributes to warming of the atmosphere and Arctic temperature amplification. Latent and sensible heat fluxes are enhanced. Net surface long-wave and solar radiation are enhanced upward and downward, respectively and are almost compensating each other. We find that the changes in the surface heat fluxes are mainly caused by the vanishing sea ice in the twenty first century. The increasing ocean heat transport leads to enhanced bottom ice melt and to an extension of the area with bottom ice melt further northward. However, no indication for a substantial impact of the increased heat transport on ice melt in the Central Arctic is found. Most of the heat that is not passed to the atmosphere in the Barents Sea is stored in the Arctic intermediate layer of Atlantic water, which is increasingly pronounced in the twenty first century.

  • 22.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Brodeau, Laurent
    Graversen, Rune Grand
    Karlsson, Johannes
    Svensson, Gunilla
    Tjernstrom, Michael
    Willén, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Arctic climate change in 21st century CMIP5 simulations with EC-Earth2013Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 40, nr 11-12, s. 2719-2743Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Arctic climate change is analyzed in an ensemble of future projection simulations performed with the global coupled climate model EC-Earth2.3. EC-Earth simulates the twentieth century Arctic climate relatively well but the Arctic is about 2 K too cold and the sea ice thickness and extent are overestimated. In the twenty-first century, the results show a continuation and strengthening of the Arctic trends observed over the recent decades, which leads to a dramatically changed Arctic climate, especially in the high emission scenario RCP8.5. The annually averaged Arctic mean near-surface temperature increases by 12 K in RCP8.5, with largest warming in the Barents Sea region. The warming is most pronounced in winter and autumn and in the lower atmosphere. The Arctic winter temperature inversion is reduced in all scenarios and disappears in RCP8.5. The Arctic becomes ice free in September in all RCP8.5 simulations after a rapid reduction event without recovery around year 2060. Taking into account the overestimation of ice in the twentieth century, our model results indicate a likely ice-free Arctic in September around 2040. Sea ice reductions are most pronounced in the Barents Sea in all RCPs, which lead to the most dramatic changes in this region. Here, surface heat fluxes are strongly enhanced and the cloudiness is substantially decreased. The meridional heat flux into the Arctic is reduced in the atmosphere but increases in the ocean. This oceanic increase is dominated by an enhanced heat flux into the Barents Sea, which strongly contributes to the large sea ice reduction and surface-air warming in this region. Increased precipitation and river runoff lead to more freshwater input into the Arctic Ocean. However, most of the additional freshwater is stored in the Arctic Ocean while the total Arctic freshwater export only slightly increases.

  • 23.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Caian, Mihaela
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Regional Arctic sea ice variations as predictor for winter climate conditions2016Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, nr 1-2, s. 317-337Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seasonal prediction skill of winter mid and high northern latitudes climate from sea ice variations in eight different Arctic regions is analyzed using detrended ERA-interim data and satellite sea ice data for the period 1980-2013. We find significant correlations between ice areas in both September and November and winter sea level pressure, air temperature and precipitation. The prediction skill is improved when using November sea ice conditions as predictor compared to September. This is particularly true for predicting winter NAO-like patterns and blocking situations in the Euro-Atlantic area. We find that sea ice variations in Barents Sea seem to be most important for the sign of the following winter NAO-negative after low ice-but amplitude and extension of the patterns are modulated by Greenland and Labrador Seas ice areas. November ice variability in the Greenland Sea provides the best prediction skill for central and western European temperature and ice variations in the Laptev/East Siberian Seas have the largest impact on the blocking number in the Euro-Atlantic region. Over North America, prediction skill is largest using September ice areas from the Pacific Arctic sector as predictor. Composite analyses of high and low regional autumn ice conditions reveal that the atmospheric response is not entirely linear suggesting changing predictive skill dependent on sign and amplitude of the anomaly. The results confirm the importance of realistic sea ice initial conditions for seasonal forecasts. However, correlations do seldom exceed 0.6 indicating that Arctic sea ice variations can only explain a part of winter climate variations in northern mid and high latitudes.

  • 24.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Devasthale, Abhay
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Karlsson, Karl-Göran
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Summer Arctic sea ice albedo in CMIP5 models2014Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 14, nr 4, s. 1987-1998Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spatial and temporal variations of summer sea ice albedo over the Arctic are analyzed using an ensemble of historical CMIP5 model simulations. The results are compared to the CLARA-SAL product that is based on long-term satellite observations. The summer sea ice albedo varies substantially among CMIP5 models, and many models show large biases compared to the CLARA-SAL product. Single summer months show an extreme spread of ice albedo among models; July values vary between 0.3 and 0.7 for individual models. The CMIP5 ensemble mean, however, agrees relatively well in the central Arctic but shows too high ice albedo near the ice edges and coasts. In most models, the ice albedo is spatially too uniformly distributed. The summer-to-summer variations seem to be underestimated in many global models, and almost no model is able to reproduce the temporal evolution of ice albedo throughout the summer fully. While the satellite observations indicate the lowest ice albedos during August, the models show minimum values in July and substantially higher values in August. Instead, the June values are often lower in the models than in the satellite observations. This is probably due to too high surface temperatures in June, leading to an early start of the melt season and too cold temperatures in August causing an earlier refreezing in the models. The summer sea ice albedo in the CMIP5 models is strongly governed by surface temperature and snow conditions, particularly during the period of melt onset in early summer and refreezing in late summer. The summer surface net solar radiation of the ice-covered Arctic areas is highly related to the ice albedo in the CMIP5 models. However, the impact of the ice albedo on the sea ice conditions in the CMIP5 models is not clearly visible. This indicates the importance of other Arctic and large-scale processes for the sea ice conditions.

  • 25.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Arctic future scenario experiments with a coupled regional climate model2011Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, nr 1, s. 69-86Artikel i tidskrift (Refereegranskat)
  • 26.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Fuentes Franco, Ramon
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Towards normal Siberian winter temperatures?2019Ingår i: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 39, nr 11, s. 4567-4574Artikel i tidskrift (Refereegranskat)
  • 27.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Gao, Y.
    Gastineau, G.
    Keenlyside, N.
    Nakamura, T.
    Ogawa, F.
    Orsolini, Y.
    Semenov, V.
    Suo, L.
    Tian, T.
    Wang, T.
    Wettstein, J. J.
    Yang, S.
    Impact of Arctic sea ice variations on winter temperature anomalies in northern hemispheric land areas2019Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 52, nr 5-6, s. 3111-3137Artikel i tidskrift (Refereegranskat)
  • 28.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Mikolajewicz, Uwe
    Seasonal to interannual climate predictability in mid and high northern latitudes in a global coupled model2009Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 32, nr 6, s. 783-798Artikel i tidskrift (Refereegranskat)
  • 29.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Mikolajewicz, Uwe
    Jungclaus, Johann H.
    Kroll, Alexandra
    Sea ice in the Barents Sea: seasonal to interannual variability and climate feedbacks in a global coupled model2009Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 32, nr 7-8, s. 1119-1138Artikel i tidskrift (Refereegranskat)
  • 30. Ogawa, Fumiaki
    et al.
    Keenlyside, Noel
    Gao, Yongqi
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Yang, Shuting
    Suo, Lingling
    Wang, Tao
    Gastineau, Guillaume
    Nakamura, Tetsu
    Cheung, Ho Nam
    Omrani, Nour-Eddine
    Ukita, Jinro
    Semenov, Vladimir
    Evaluating Impacts of Recent Arctic Sea Ice Loss on the Northern Hemisphere Winter Climate Change2018Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, nr 7, s. 3255-3263Artikel i tidskrift (Refereegranskat)
  • 31. Paquin, Jean-Philippe
    et al.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Sushama, Laxmi
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Causes and consequences of mid-21st-century rapid ice loss events simulated by the Rossby centre regional atmosphere-ocean model2013Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 65, artikel-id 19110Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent observations and modelling studies suggest that the Arctic climate is undergoing important transition. One manifestation of this change is seen in the rapid sea-ice cover decrease as experienced in 2007 and 2012. Although most numerical climate models cannot adequately reproduce the recent changes, some models produce similar Rapid Ice Loss Events (RILEs) during the mid-21st-century. This study presents an analysis of four specific RILEs clustered around 2040 in three transient climate projections performed with the coupled Rossby Centre regional Atmosphere-Ocean model (RCAO). The analysis shows that long-term thinning causes increased vulnerability of the Arctic Ocean sea-ice cover. In the Atlantic sector, pre-conditioning (thinning of sea ice) combined with anomalous atmospheric and oceanic heat transport causes large ice loss, while in the Pacific sector of the Arctic Ocean sea-ice albedo feedback appears important, particularly along the retreating sea-ice margin. Although maximum sea-ice loss occurs in the autumn, response in surface air temperature occurs in early winter, caused by strong increase in ocean-atmosphere surface energy fluxes, mainly the turbulent fluxes. Synchronicity of the events around 2040 in the projections is caused by a strong large-scale atmospheric circulation anomaly at the Atlantic lateral boundary of the regional model. The limited impact on land is caused by vertical propagation of the surface heat anomaly rather than horizontal, caused by the absence of low-level temperature inversion over the ocean.

  • 32. Smith, D. M.
    et al.
    Scaife, A. A.
    Hawkins, E.
    Bilbao, R.
    Boer, G. J.
    Caian, Mihaela
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Caron, L. -P
    Danabasoglu, G.
    Delworth, T.
    Doblas-Reyes, F. J.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Dunstone, N. J.
    Eade, R.
    Hermanson, L.
    Ishii, M.
    Kharin, V.
    Kimoto, M.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kushnir, Y.
    Matei, D.
    Meehl, G. A.
    Menegoz, M.
    Merryfield, W. J.
    Mochizuki, T.
    Mueller, W. A.
    Pohlmann, H.
    Power, S.
    Rixen, M.
    Sospedra-Alfonso, R.
    Tuma, M.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Yang, X.
    Yeager, S.
    Predicted Chance That Global Warming Will Temporarily Exceed 1.5 degrees C2018Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, nr 21, s. 11895-11903Artikel i tidskrift (Refereegranskat)
  • 33. Sterl, Andreas
    et al.
    Bintanja, Richard
    Brodeau, Laurent
    Gleeson, Emily
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Schmith, Torben
    Semmler, Tido
    Severijns, Camiel
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Yang, Shuting
    A look at the ocean in the EC-Earth climate model2012Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 39, nr 11, s. 2631-2657Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    EC-Earth is a newly developed global climate system model. Its core components are the Integrated Forecast System (IFS) of the European Centre for Medium Range Weather Forecasts (ECMWF) as the atmosphere component and the Nucleus for European Modelling of the Ocean (NEMO) developed by Institute Pierre Simon Laplace (IPSL) as the ocean component. Both components are used with a horizontal resolution of roughly one degree. In this paper we describe the performance of NEMO in the coupled system by comparing model output with ocean observations. We concentrate on the surface ocean and mass transports. It appears that in general the model has a cold and fresh bias, but a much too warm Southern Ocean. While sea ice concentration and extent have realistic values, the ice tends to be too thick along the Siberian coast. Transports through important straits have realistic values, but generally are at the lower end of the range of observational estimates. Exceptions are very narrow straits (Gibraltar, Bering) which are too wide due to the limited resolution. Consequently the modelled transports through them are too high. The strength of the Atlantic meridional overturning circulation is also at the lower end of observational estimates. The interannual variability of key variables and correlations between them are realistic in size and pattern. This is especially true for the variability of surface temperature in the tropical Pacific (El Nio). Overall the ocean component of EC-Earth performs well and helps making EC-Earth a reliable climate model.

  • 34.
    Thomas, Manu
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Devasthale, Abhay
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Roberts, Malcolm
    Roberts, Christopher
    Lohmann, Katja
    A statistical and process-oriented evaluation of cloud radiative effects in high-resolution global models2019Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 12, nr 4, s. 1679-1702Artikel i tidskrift (Refereegranskat)
  • 35.
    Thomas, Manu
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Devasthale, Abhay
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    L'Ecuyer, Tristan
    Wang, Shiyu
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Snowfall distribution and its response to the Arctic Oscillation: an evaluation of HighResMIP models in the Arctic using CPR/CloudSat observations2019Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 12, nr 8, s. 3759-3772Artikel i tidskrift (Refereegranskat)
  • 36. Vanniere, Benoit
    et al.
    Demory, Marie-Estelle
    Vidale, Pier Luigi
    Schiemann, Reinhard
    Roberts, Malcolm J.
    Roberts, Christopher D.
    Matsueda, Mio
    Terray, Laurent
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Senan, Retish
    Multi-model evaluation of the sensitivity of the global energy budget and hydrological cycle to resolution2019Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 52, nr 11, s. 6817-6846Artikel i tidskrift (Refereegranskat)
  • 37. Zhang, Wenxin
    et al.
    Miller, Paul A.
    Smith, Benjamin
    Wania, Rita
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Tundra shrubification and tree-line advance amplify arctic climate warming: results from an individual-based dynamic vegetation model2013Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 8, nr 3, artikel-id 034023Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One major challenge to the improvement of regional climate scenarios for the northern high latitudes is to understand land surface feedbacks associated with vegetation shifts and ecosystem biogeochemical cycling. We employed a customized, Arctic version of the individual-based dynamic vegetation model LPJ-GUESS to simulate the dynamics of upland and wetland ecosystems under a regional climate model-downscaled future climate projection for the Arctic and Subarctic. The simulated vegetation distribution (1961-1990) agreed well with a composite map of actual arctic vegetation. In the future (2051-2080), a poleward advance of the forest-tundra boundary, an expansion of tall shrub tundra, and a dominance shift from deciduous to evergreen boreal conifer forest over northern Eurasia were simulated. Ecosystems continued to sink carbon for the next few decades, although the size of these sinks diminished by the late 21st century. Hot spots of increased CH4 emission were identified in the peatlands near Hudson Bay and western Siberia. In terms of their net impact on regional climate forcing, positive feedbacks associated with the negative effects of tree-line, shrub cover and forest phenology changes on snow-season albedo, as well as the larger sources of CH4, may potentially dominate over negative feedbacks due to increased carbon sequestration and increased latent heat flux.

1 - 37 av 37
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