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  • 201.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Changes in seasonal mean European temperature and precipitation climate from an ensemble of transient RCM simulations driven by several AOGCMs2009Conference paper (Other academic)
  • 202.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Climate change in the Baltic Sea area in an ensemble of regional climate model simulations2010Conference paper (Other academic)
  • 203.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    An ensemble of regional climate change simulations2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M., 2009, p. 134-135Conference paper (Other academic)
  • 204.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    21st century changes in the European climate: uncertainties derived from an ensemble of regional climate model simulations2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, no 1, p. 24-40Article in journal (Refereed)
  • 205.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    21st century changes in the Nordic climate: 8ncertainties derived from an ensemble of regional climate model simulations2010Conference paper (Other academic)
  • 206.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Seasonal mean temperature, precipitation and wind speed in Europe from an ensemble of 16 transient RCM simulations for 1961-21002010In: Geophysical Research Abstracts, 2010, Vol. 12, article id EGU2010-10229Conference paper (Refereed)
  • 207.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Ole Bossing
    Jacob, Daniela
    Keuler, Klaus
    Lenderink, Geert
    van Meijgaard, Erik
    Schar, Christoph
    Somot, Samuel
    Sorland, Silje Lund
    Teichmann, Claas
    Vautard, Robert
    European climate change at global mean temperature increases of 1.5 and 2 degrees C above pre-industrial conditions as simulated by the EURO-CORDEX regional climate models2018In: Earth System Dynamics, ISSN 2190-4979, E-ISSN 2190-4987, Vol. 9, no 2, p. 459-478Article in journal (Refereed)
  • 208.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Ruosteenoja, Kimmo
    Present-day and future precipitation in the Baltic Sea region as simulated in a suite of regional climate models2007In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 81, p. 281-291Article in journal (Refereed)
    Abstract [en]

    Here we investigate simulated changes in the precipitation climate over the Baltic Sea and surrounding land areas for the period 2071-2100 as compared to 1961-1990. We analyze precipitation in 10 regional climate models taking part in the European PRUDENCE project. Forced by the same global driving climate model, the mean of the regional climate model simulations captures the observed climatological precipitation over the Baltic Sea runoff land area to within 15% in each month, while single regional models have errors up to 25%. In the future climate, the precipitation is projected to increase in the Baltic Sea area, especially during winter. During summer increased precipitation in the north is contrasted with a decrease in the south of this region. Over the Baltic Sea itself the future change in the seasonal cycle of precipitation is markedly different in the regional climate model simulations. We show that the sea surface temperatures have a profound impact on the simulated hydrological cycle over the Baltic Sea. The driving global climate model used in the common experiment projects a very strong regional increase in summertime sea surface temperature, leading to a significant increase in precipitation. In addition to the common experiment some regional models have been forced by either a different set of Baltic Sea surface temperatures, lateral boundary conditions from another global climate model, a different emission scenario, or different initial conditions. We make use of the large number of experiments in the PRUDENCE project, providing an ensemble consisting of more than 25 realizations of climate change, to illustrate sources of uncertainties in climate change projections.

  • 209.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Thejll, Peter
    Rummukainen, Markku
    SMHI, Core Services.
    Christensen, Jens H.
    Boberg, Fredrik
    Christensen, Ole B.
    Maule, Cathrine Fox
    Emerging regional climate change signals for Europe under varying large-scale circulation conditions2013In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 56, no 2, p. 103-119Article in journal (Refereed)
    Abstract [en]

    A large ensemble of regional climate model projections was investigated regarding if and when they show an emergence of significant climate change signals in seasonal temperature and precipitation within Europe. The influence of the North Atlantic Oscillation (NAO), as simulated in the projections, was investigated. In most parts of Europe, the projections indicate robust emergence of temperature change in the first 2 decades of the 21st century, typically earlier for summer than for winter. For precipitation changes, signals generally emerge much later than for temperature. For Europe as a whole, the precipitation signals tend to emerge some 40 to 60 yr later than the temperature signals. In some sub-regions, robust signals for precipitation are not found within the studied period, i.e. until 2100. Some sub-regions, notably the Mediterranean area and Scandinavia, show different behaviour in some aspects compared to the ensemble-based results as a whole. NAO has some influence on the temperature change signals, which emerge earlier in winter for some models and regions if NAO is accounted for. For summer temperatures, the influence of NAO is less evident. Similarly, for precipitation, accounting for NAO leads to an earlier emergence in some regions and models. Here, we find an impact for both summer and winter.

  • 210. Klein, Cornelia
    et al.
    Belusic, Danijel
    SMHI, Research Department, Climate research - Rossby Centre.
    Taylor, Christopher M.
    Wavelet Scale Analysis of Mesoscale Convective Systems for Detecting Deep Convection From Infrared Imagery2018In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 123, no 6, p. 3035-3050Article in journal (Refereed)
  • 211.
    Klein, Thomas
    et al.
    SMHI, Core Services.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Frankenberg, Britt
    SMHI, Core Services.
    Svensson, J
    SMHI.
    Broman, Barry
    SMHI, Research Department, Climate research - Rossby Centre.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    ECDS - a Swedish Research Infrastructure for the Open Sharing of Environment and Climate Data2013In: Data Science Journal, ISSN 1683-1470, E-ISSN 1683-1470, no 12, p. 1-9Article in journal (Refereed)
  • 212. Klingaman, Nicholas P.
    et al.
    Woolnough, Steven J.
    Jiang, Xianan
    Waliser, Duane
    Xavier, Prince K.
    Petch, Jon
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Hannay, Cecile
    Kim, Daehyun
    Ma, Hsi-Yen
    Merryfield, William J.
    Miyakawa, Tomoki
    Pritchard, Mike
    Ridout, James A.
    Roehrig, Romain
    Shindo, Eiki
    Vitart, Frederic
    Wang, Hailan
    Cavanaugh, Nicholas R.
    Mapes, Brian E.
    Shelly, Ann
    Zhang, Guang J.
    Vertical structure and physical processes of the Madden-Julian oscillation: Linking hindcast fidelity to simulated diabatic heating and moistening2015In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 120, no 10, p. 4690-4717Article in journal (Refereed)
    Abstract [en]

    Many theories for the Madden-Julian oscillation (MJO) focus on diabatic processes, particularly the evolution of vertical heating and moistening. Poor MJO performance in weather and climate models is often blamed on biases in these processes and their interactions with the large-scale circulation. We introduce one of the three components of a model evaluation project, which aims to connect MJO fidelity in models to their representations of several physical processes, focusing on diabatic heating and moistening. This component consists of 20day hindcasts, initialized daily during two MJO events in winter 2009-2010. The 13 models exhibit a range of skill: several have accurate forecasts to 20days lead, while others perform similarly to statistical models (8-11days). Models that maintain the observed MJO amplitude accurately predict propagation, but not vice versa. We find no link between hindcast fidelity and the precipitation-moisture relationship, in contrast to other recent studies. There is also no relationship between models' performance and the evolution of their diabatic heating profiles with rain rate. A more robust association emerges between models' fidelity and net moistening: the highest-skill models show a clear transition from low-level moistening for light rainfall to midlevel moistening at moderate rainfall and upper level moistening for heavy rainfall. The midlevel moistening, arising from both dynamics and physics, may be most important. Accurately representing many processes may be necessary but not sufficient for capturing the MJO, which suggests that models fail to predict the MJO for a broad range of reasons and limits the possibility of finding a panacea.

  • 213. Klutse, Nana Ama Browne
    et al.
    Ajayi, Vincent O.
    Gbobaniyi, Bode
    SMHI, Professional Services.
    Egbebiyi, Temitope S.
    Kouadio, Kouakou
    Nkrumah, Francis
    Quagraine, Kwesi Akumenyi
    Olusegun, Christiana
    Diasso, Ulrich
    Abiodun, Babatunde J.
    Lawal, Kamoru
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Lennard, Christopher
    Dosio, Alessandro
    Potential impact of 1.5 degrees C and 2 degrees C global warming on consecutive dry and wet days over West Africa2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 5, article id 055013Article in journal (Refereed)
  • 214. Klutse, Nana Ama Browne
    et al.
    Sylla, Mouhamadou Bamba
    Diallo, Ismaila
    Sarr, Abdoulaye
    Dosio, Alessandro
    Diedhiou, Arona
    Kamga, Andre
    Lamptey, Benjamin
    Ali, Abdou
    Gbobaniyi, Emiola O.
    Owusu, Kwadwo
    Lennard, Christopher
    Hewitson, Bruce
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    Daily characteristics of West African summer monsoon precipitation in CORDEX simulations2016In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 123, no 1-2, p. 369-386Article in journal (Refereed)
    Abstract [en]

    We analyze and intercompare the performance of a set of ten regional climate models (RCMs) along with the ensemble mean of their statistics in simulating daily precipitation characteristics during the West African monsoon (WAM) period (June-July-August-September). The experiments are conducted within the framework of the COordinated Regional Downscaling Experiments for the African domain. We find that the RCMs exhibit substantial differences that are associated with a wide range of estimates of higher-order statistics, such as intensity, frequency, and daily extremes mostly driven by the convective scheme employed. For instance, a number of the RCMs simulate a similar number of wet days compared to observations but greater rainfall intensity, especially in oceanic regions adjacent to the Guinea Highlands because of a larger number of heavy precipitation events. Other models exhibit a higher wet-day frequency but much lower rainfall intensity over West Africa due to the occurrence of less frequent heavy rainfall events. This indicates the existence of large uncertainties related to the simulation of daily rainfall characteristics by the RCMs. The ensemble mean of the indices substantially improves the RCMs' simulated frequency and intensity of precipitation events, moderately outperforms that of the 95th percentile, and provides mixed benefits for the dry and wet spells. Although the ensemble mean improved results cannot be generalized, such an approach produces encouraging results and can help, to some extent, to improve the robustness of the response of the WAM daily precipitation to the anthropogenic greenhouse gas warming.

  • 215. Knist, Sebastian
    et al.
    Goergen, Klaus
    Buonomo, Erasmo
    Christensen, Ole Bossing
    Colette, Augustin
    Cardoso, Rita M.
    Fealy, Rowan
    Fernandez, Jesus
    Garcia-Diez, Markel
    Jacob, Daniela
    Kartsios, Stergios
    Katragkou, Eleni
    Keuler, Klaus
    Mayer, Stephanie
    van Meijgaard, Erik
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Soares, Pedro M. M.
    Sobolowski, Stefan
    Szepszo, Gabriella
    Teichmann, Claas
    Vautard, Robert
    Warrach-Sagi, Kirsten
    Wulfmeyer, Volker
    Simmer, Clemens
    Land-atmosphere coupling in EURO-CORDEX evaluation experiments2017In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 122, no 1, p. 79-103Article in journal (Refereed)
  • 216.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Beatty, Christof Konig
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Potential decadal predictability and its sensitivity to sea ice albedo parameterization in a global coupled model2012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 38, no 11-12, p. 2389-2408Article in journal (Refereed)
    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.

  • 217.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Berg, Peter
    SMHI, Research Department, Hydrology.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Arctic climate change in an ensemble of regional CORDEX simulations2015In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 34, article id 24603Article in journal (Refereed)
    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.

  • 218.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brodeau, Laurent
    Arctic climate and its interaction with lower latitudes under different levels of anthropogenic warming in a global coupled climate model2017In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 49, no 1-2, p. 471-492Article in journal (Refereed)
  • 219.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brodeau, Laurent
    Ocean heat transport into the Arctic in the twentieth and twenty-first century in EC-Earth2014In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 42, no 11-12, p. 3101-3120Article in journal (Refereed)
    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.

  • 220.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brodeau, Laurent
    Graversen, Rune Grand
    Karlsson, Johannes
    Svensson, Gunilla
    Tjernstrom, Michael
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Arctic climate change in 21st century CMIP5 simulations with EC-Earth2013In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 40, no 11-12, p. 2719-2743Article in journal (Refereed)
    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.

  • 221.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Regional Arctic sea ice variations as predictor for winter climate conditions2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 1-2, p. 317-337Article in journal (Refereed)
    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.

  • 222.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Karlsson, Karl-Göran
    SMHI, Research Department, Atmospheric remote sensing.
    Summer Arctic sea ice albedo in CMIP5 models2014In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 14, no 4, p. 1987-1998Article in journal (Refereed)
    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.

  • 223.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Arctic future scenario experiments with a coupled regional climate model2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, no 1, p. 69-86Article in journal (Refereed)
  • 224.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Fuentes Franco, Ramon
    SMHI, Research Department, Climate research - Rossby Centre.
    Towards normal Siberian winter temperatures?2019In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 39, no 11, p. 4567-4574Article in journal (Refereed)
  • 225.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - 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 areas2019In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 52, no 5-6, p. 3111-3137Article in journal (Refereed)
  • 226.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Mikolajewicz, Uwe
    Seasonal to interannual climate predictability in mid and high northern latitudes in a global coupled model2009In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 32, no 6, p. 783-798Article in journal (Refereed)
  • 227.
    Koenigk, Torben
    et al.
    SMHI, Research Department, Climate research - 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 model2009In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 32, no 7-8, p. 1119-1138Article in journal (Refereed)
  • 228. Kotlarski, S.
    et al.
    Keuler, K.
    Christensen, O. B.
    Colette, A.
    Deque, M.
    Gobiet, A.
    Goergen, K.
    Jacob, D.
    Luethi, D.
    van Meijgaard, E.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Schaer, C.
    Teichmann, C.
    Vautard, R.
    Warrach-Sagi, K.
    Wulfmeyer, V.
    Regional climate modeling on European scales: a joint standard evaluation of the EURO-CORDEX RCM ensemble2014In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 7, no 4, p. 1297-1333Article in journal (Refereed)
    Abstract [en]

    EURO-CORDEX is an international climate downscaling initiative that aims to provide high-resolution climate scenarios for Europe. Here an evaluation of the ERA-Interim-driven EURO-CORDEX regional climate model (RCM) ensemble is presented. The study documents the performance of the individual models in representing the basic spatiotemporal patterns of the European climate for the period 1989-2008. Model evaluation focuses on near-surface air temperature and precipitation, and uses the E-OBS data set as observational reference. The ensemble consists of 17 simulations carried out by seven different models at grid resolutions of 12 km (nine experiments) and 50 km (eight experiments). Several performance metrics computed from monthly and seasonal mean values are used to assess model performance over eight subdomains of the European continent. Results are compared to those for the ERA40-driven ENSEMBLES simulations. The analysis confirms the ability of RCMs to capture the basic features of the European climate, including its variability in space and time. But it also identifies nonnegligible deficiencies of the simulations for selected metrics, regions and seasons. Seasonally and regionally averaged temperature biases are mostly smaller than 1.5 degrees C, while precipitation biases are typically located in the +/- 40% range. Some bias characteristics, such as a predominant cold and wet bias in most seasons and over most parts of Europe and a warm and dry summer bias over southern and southeastern Europe reflect common model biases. For seasonal mean quantities averaged over large European subdomains, no clear benefit of an increased spatial resolution (12 vs. 50 km) can be identified. The bias ranges of the EURO-CORDEX ensemble mostly correspond to those of the ENSEMBLES simulations, but some improvements in model performance can be identified (e. g., a less pronounced southern European warm summer bias). The temperature bias spread across different configurations of one individual model can be of a similar magnitude as the spread across different models, demonstrating a strong influence of the specific choices in physical parameterizations and experimental setup on model performance. Based on a number of simply reproducible metrics, the present study quantifies the currently achievable accuracy of RCMs used for regional climate simulations over Europe and provides a quality standard for future model developments.

  • 229. Koutroulis, A. G.
    et al.
    Papadimitriou, L. V.
    Grillakis, M. G.
    Tsanis, I. K.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Betts, R. A.
    Freshwater vulnerability under high end climate change. A pan-European assessment2018In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 613, p. 271-286Article in journal (Refereed)
  • 230. Koutroulis, Aristeidis G.
    et al.
    Papadimitriou, Lamprini V.
    Grillakis, Manolis G.
    Tsanis, Ioannis K.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Caesar, John
    Betts, Richard A.
    Simulating Hydrological Impacts under Climate Change: Implications from Methodological Differences of a Pan European Assessment2018In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 10, no 10, article id 1331Article in journal (Refereed)
  • 231. Krueger, Oliver
    et al.
    Feser, Frauke
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Kaas, Eigil
    Schmith, Torben
    Tuomenvirta, Heikki
    von Storch, Hans
    Comment on "Trends and low frequency variability of extra-tropical cyclone activity in the ensemble of twentieth century reanalysis" by Xiaolan L. Wang, Y. Feng, G. P. Compo, V. R. Swail, F. W. Zwiers, R. J. Allan, and P. D. Sardeshmukh, Climate Dynamics, 20122014In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 42, no 3-4, p. 1127-1128Article in journal (Other academic)
    Abstract [en]

    The main subject of this article is to comment on the issue of storminess trends derived from the twentieth century reanalysis (20CR) and from observations in the North Atlantic region written about in Wang et al. (Clim Dyn 40(11-12):2775-2800, 2012). The statement that the 20CR estimates would be consistent with storminess derived from pressure-based proxies does not hold for the time prior to 1950.

  • 232. Kumar, Pankaj
    et al.
    Wiltshire, Andrew
    Mathison, Camilla
    Asharaf, Shakeel
    Ahrens, Bodo
    Lucas-Picher, Philippe
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Jens H.
    Gobiet, Andreas
    Saeed, Fahad
    Hagemann, Stefan
    Jacob, Daniela
    Downscaled climate change projections with uncertainty assessment over India using a high resolution multi-model approach2013In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 468, p. S18-S30Article in journal (Refereed)
    Abstract [en]

    This study presents the possible regional climate change over South Asia with a focus over India as simulated by three very high resolution regional climate models (RCMs). One of the most striking results is a robust increase in monsoon precipitation by the end of the 21st century but regional differences in strength. First the ability of RCMs to simulate the monsoon climate is analyzed. For this purpose all three RCMs are forced with ECMWF reanalysis data for the period 1989-2008 at a horizontal resolution of similar to 25 km. The results are compared against independent observations. In order to simulate future climate the models are driven by lateral boundary conditions from two global climate models (GCMs: ECHAM5-MPIOM and HadCM3) using the SRES A1B scenario, except for one RCM, which only used data from one GCM. The results are presented for the full transient simulation period 1970-2099 and also for several time slices. The analysis concentrates on precipitation and temperature over land. All models show a clear signal of gradually wide-spread warming throughout the 21st century. The ensemble-mean warming over India is 1.5 degrees C at the end of 2050, whereas it is 3.9 degrees C at the end of century with respect to 1970-1999. The pattern of projected precipitation changes shows considerable spatial variability, with an increase in precipitation over the peninsular of India and coastal areas and, either no change or decrease further inland. From the analysis of a larger ensemble of global climate models using the A1B scenario a wide spread warming (similar to 3.2 degrees C) and an overall increase (similar to 8.5%) in mean monsoon precipitation by the end of the 21st century is very likely. The influence of the driving GCM on the projected precipitation change simulated with each RCM is as strong as the variability among the RCMs driven with one. (C) 2013 Elsevier B.V. All rights reserved.

  • 233. Kuttippurath, J.
    et al.
    Godin-Beekmann, S.
    Lefevre, F.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Santee, M. L.
    Froidevaux, L.
    Record-breaking ozone loss in the Arctic winter 2010/2011: comparison with 1996/19972012In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, no 15, p. 7073-7085Article in journal (Refereed)
    Abstract [en]

    We present a detailed discussion of the chemical and dynamical processes in the Arctic winters 1996/1997 and 2010/2011 with high resolution chemical transport model (CTM) simulations and space-based observations. In the Arctic winter 2010/2011, the lower stratospheric minimum temperatures were below 195K for a record period of time, from December to mid-April, and a strong and stable vortex was present during that period. Simulations with the Mimosa-Chim CTM show that the chemical ozone loss started in early January and progressed slowly to 1 ppmv (parts per million by volume) by late February. The loss intensified by early March and reached a record maximum of similar to 2.4 ppmv in the late March-early April period over a broad altitude range of 450-550 K. This coincides with elevated ozone loss rates of 2-4 ppbv sh(-1) (parts per billion by volume/sunlit hour) and a contribution of about 30-55% and 30-35% from the ClO-ClO and ClO-BrO cycles, respectively, in late February and March. In addition, a contribution of 30-50% from the HOx cycle is also estimated in April. We also estimate a loss of about 0.7-1.2 ppmv contributed (75%) by the NOx cycle at 550-700 K. The ozone loss estimated in the partial column range of 350-550K exhibits a record value of similar to 148DU (Dobson Unit). This is the largest ozone loss ever estimated in the Arctic and is consistent with the remarkable chlorine activation and strong denitrification (40-50%) during the winter, as the modeled ClO shows similar to 1.8 ppbv in early January and similar to 1 ppbv in March at 450-550 K. These model results are in excellent agreement with those found from the Aura Microwave Limb Sounder observations. Our analyses also show that the ozone loss in 2010/2011 is close to that found in some Antarctic winters, for the first time in the observed history. Though the winter 1996/1997 was also very cold in March-April, the temperatures were higher in December-February, and, therefore, chlorine activation was moderate and ozone loss was average with about 1.2 ppmv at 475-550K or 42DU at 350-550 K, as diagnosed from the model simulations and measurements.

  • 234. Kuttippurath, J.
    et al.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    A comparative study of the major sudden stratospheric warmings in the Arctic winters 2003/2004-2009/20102012In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, no 17, p. 8115-8129Article in journal (Refereed)
    Abstract [en]

    We present an analysis of the major sudden stratospheric warmings (SSWs) in the Arctic winters 2003/04-2009/10. There were 6 major SSWs (major warmings [MWs]) in 6 out of the 7 winters, in which the MWs of 2003/04, 2005/06, and 2008/09 were in January and those of 2006/07, 2007/08, and 2009/10 were in February. Although the winter 2009/10 was relatively cold from mid-December to mid-January, strong wave 1 activity led to a MW in early February, for which the largest momentum flux among the winters was estimated at 60 degrees N/10 hPa, about 450 m(2) s(-2). The strongest MW, however, was observed in 2008/09 and the weakest in 2006/07. The MW in 2008/09 was triggered by intense wave 2 activity and was a vortex split event. In contrast, strong wave 1 activity led to the MWs of other winters and were vortex displacement events. Large amounts of Eliassen-Palm (EP) and wave 1/2 EP fluxes (about 2-4x10(5) kg s-2) are estimated shortly before the MWs at 100 hPa averaged over 45-75 degrees N in all winters, suggesting profound tropospheric forcing for the MWs. We observe an increase in the occurrence of MWs (similar to 1.1 MWs/winter) in recent years (1998/99-2009/10), as there were 13MWs in the 12 Arctic winters, although the long-term average (1957/58-2009/10) of the frequency stays around its historical value (similar to 0.7 MWs/winter), consistent with the findings of previous studies. An analysis of the chemical ozone loss in the past 17 Arctic winters (1993/94-2009/10) suggests that the loss is inversely proportional to the intensity and timing of MWs in each winter, where early (December-January) MWs lead to minimal ozone loss. Therefore, this high frequency of MWs in recent Arctic winters has significant implications for stratospheric ozone trends in the northern hemisphere.

  • 235. Kuttippurath, Jayanarayanan
    et al.
    Kleinboehl, Armin
    Sinnhuber, Miriam
    Bremer, Holger
    Kuellmann, Harry
    Notholt, Justus
    Godin-Beekmann, Sophie
    Tripathi, Omprakash
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Arctic ozone depletion in 2002-2003 measured by ASUR and comparison with POAM observations2011In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 116, article id D22305Article in journal (Refereed)
    Abstract [en]

    We present ozone loss estimated from airborne measurements taken during January-February and March in the Arctic winter 2002/2003. The first half of the winter was characterized by unusually cold temperatures and the second half by a major stratospheric sudden warming around 15-18 January 2003. The potential vorticity maps show a vortex split in the lower stratosphere during the major warming (MW) in late January and during the minor warming in mid-February due to wave 1 amplification. However, the warming can be termed as a vortex displacement event as there was no vortex split during the MW period at 10 hPa. Very low temperatures, large areas of polar stratospheric clouds (PSCs), and high chlorine activation triggered significant ozone loss in the early winter, as the vortex moved to the midlatitude regions. The ozone depletion derived from the ASUR measurements sampled inside the vortex, in conjunction with the Mimosa-Chim model tracer, shows a maximum of 1.3 +/- 0.2 ppmv at 450-500 K by late March. The partial column loss derived from the ASUR ozone profiles reaches up to 61 +/- 4 DU in 400-550 K in the same period. The evolution of ozone and ozone loss assessed from the ASUR measurements is in very good agreement with POAM observations. The reduction in ozone estimated from the POAM measurements shows a similar maximum of 1.3 +/- 0.2 ppmv at 400-500 K or 63 +/- 4 DU in 400-550 K in late March. Our study reveals that the Arctic winter 2002/2003 was unique as it had three minor warmings and a MW, yet showed large loss in ozone. No such feature was observed in any other Arctic winter in the 1989-2010 period. In addition, an unusually large ozone loss in December, around 0.5 +/- 0.2 ppmv at 450-500 K or 12 +/- 1 DU in 400-550 K, was estimated for the first time in the Arctic. A careful and detailed diagnosis with all available published results for this winter exhibits an average ozone loss of 1.5 +/- 0.3 ppmv at 450-500 K or 65 +/- 5 DU in 400-550 K by the end of March, which exactly matches the ozone depletion derived from the ASUR, POAM and model data. The early ozone loss together with considerable loss afterwards put the warm Arctic winter 2002/2003 amongst the moderately cold winters in terms of the significance of the ozone loss.

  • 236. Laiti, L.
    et al.
    Mallucci, S.
    Piccolroaz, S.
    Bellin, A.
    Zardi, D.
    Fiori, A.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Majone, B.
    Testing the Hydrological Coherence of High-Resolution Gridded Precipitation and Temperature Data Sets2018In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 54, no 3, p. 1999-2016Article in journal (Refereed)
  • 237.
    Lake, Irene
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Gutowski, William
    Giorgi, Filipo
    Lee, Boram
    CORDEX Climate Research and Information for Regions2017In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 98, no 8, p. ES189-ES192Article in journal (Refereed)
  • 238. Lang, Francisco
    et al.
    Belusic, Danijel
    SMHI, Research Department, Climate research - Rossby Centre.
    Siems, Steven
    Observations of Wind-Direction Variability in the Nocturnal Boundary Layer2018In: Boundary-layer Meteorology, ISSN 0006-8314, E-ISSN 1573-1472, Vol. 166, no 1, p. 51-68Article in journal (Refereed)
  • 239.
    Langner, Joakim
    et al.
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Air pollution Assessment Study Using the MATCH Modelling System: Application to sulfur and nitrogen compounds over Sweden 19941996Report (Other academic)
  • 240.
    Langner, Joakim
    et al.
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Validation of the operational emergency response model at the Swedish Meteorological and Hydrological Institute using data from ETEX and the Chernobyl accident1998In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 32, no 24, p. 4325-4333Article in journal (Refereed)
    Abstract [en]

    The Eulerian atmospheric tracer transport model MATCH (Multiscale Atmospheric Transport and Chemistry model) has been extended with a Lagrangian particle model treating the initial dispersion of pollutants from point sources. The model has been implemented at the Swedish Meteorological and Hydrological Institute in an emergency response system for nuclear accidents and can be activated on short notice to provide forecast concentration and deposition fields. The model has been used to simulate the transport of the inert tracer released during the ETEX experiment and the transport and deposition of Cs-137 from the Chernobyl accident. Visual inspection of the results as well as statistical analysis shows that the extent, time of arrival and duration of the tracer cloud, is in good agreement with the observations for both cases, with a tendency towards over-prediction for the first ETEX release. For the Chernobyl case the simulated deposition pattern over Scandinavia and over Europe as a whole agrees with observations when observed precipitation is used in the simulation. When model calculated precipitation is used, the quality of the simulation is reduced significantly and the model fails to predict major features of the observed deposition held. (C) 1998 Elsevier Science Ltd. All rights reserved.

  • 241. Lauer, Axel
    et al.
    Eyring, Veronika
    Righi, Mattia
    Buchwitz, Michael
    Defourny, Pierre
    Evaldsson, Martin
    SMHI, Research Department, Climate research - Rossby Centre.
    Friedlingstein, Pierre
    de Jeu, Richard
    de Leeuw, Gerrit
    Loew, Alexander
    Merchant, Christopher J.
    Mueller, Benjamin
    Popp, Thomas
    Reuter, Maximilian
    Sandven, Stein
    Senftleben, Daniel
    Stengel, Martin
    Van Roozendael, Michel
    Wenzel, Sabrina
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Benchmarking CMIP5 models with a subset of ESA CCI Phase 2 data using the ESMValTool2017In: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 203, p. 9-39Article in journal (Refereed)
  • 242. Lauer, Axel
    et al.
    Jones, Colin
    Eyring, Veronika
    Evaldsson, Martin
    SMHI, Research Department, Climate research - Rossby Centre.
    Stefan, Hagemann A.
    Makela, Jarmo
    Martin, Gill
    Roehrig, Romain
    Wang, Shiyu
    SMHI, Research Department, Climate research - Rossby Centre.
    Process-level improvements in CMIP5 models and their impact on tropical variability, the Southern Ocean, and monsoons2018In: Earth System Dynamics, ISSN 2190-4979, E-ISSN 2190-4987, Vol. 9, no 1, p. 33-67Article in journal (Refereed)
  • 243. Leedale, Joseph
    et al.
    Tompkins, Adrian M.
    Caminade, Cyril
    Jones, Anne E.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Morse, Andrew P.
    Projecting malaria hazard from climate change in eastern Africa using large ensembles to estimate uncertainty2016In: GEOSPATIAL HEALTH, ISSN 1827-1987, Vol. 11, p. 102-114Article in journal (Refereed)
  • 244. Lenderink, G
    et al.
    Siebesma, A P
    Cheinet, S
    Irons, S
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Marquet, P
    Muller, F
    Olmeda, D
    Calvo, J
    Sanchez, E
    Soares, P M M
    The diurnal cycle of shallow cumulus clouds over land: A single-column model intercomparison study2004In: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 130, no 604, p. 3339-3364Article in journal (Refereed)
    Abstract [en]

    An intercomparison study for single-column models (SCMs) of the diurnal cycle of shallow cumulus convection is reported. The case, based on measurements at the Atmospheric Radiation Measurement program Southern Great Plains site on 21 June 1997, has been used in a large-eddy simulation intercomparison study before. Results of the SCMs reveal the following general deficiencies: too large values of cloud cover and Cloud liquid water, unrealistic thermodynamic profiles, and high amounts of numerical noise. Results are also strongly dependent on vertical resolution. These results are analysed in terms of the behaviour of the different parametrization schemes involved: the convection scheme, the turbulence scheme, and the cloud scheme. In general the behaviour of the SCMs can be grouped in two different classes: one class with too strong mixing by the turbulence scheme, the other class with too strong activity by the convection scheme. The coupling between (subcloud) turbulence and the convection scheme plays a crucial role. Finally, (in part) motivated by these results several models have been successfully updated with new parametrization schemes and/or their present schemes have been successfully modified.

  • 245. Lenderink, Geert
    et al.
    Belusic, Danijel
    SMHI, Research Department, Climate research - Rossby Centre.
    Fowler, Hayley J.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Lind, Petter
    SMHI, Research Department, Climate research - Rossby Centre.
    van Meijgaard, Erik
    van Ulft, Bert
    de Vries, Hylke
    Systematic increases in the thermodynamic response of hourly precipitation extremes in an idealized warming experiment with a convection-permitting climate model2019In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 14, no 7, article id 074012Article in journal (Refereed)
  • 246. Lennard, C. J.
    et al.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Dosio, A.
    Moufouma-Okia, W.
    On the need for regional climate information over Africa under varying levels of global warming2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 060401Article in journal (Refereed)
  • 247. Leroux, Stephanie
    et al.
    Bellon, Gilles
    Roehrig, Romain
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Klingaman, Nicholas P.
    Lafore, Jean-Philippe
    Musat, Ionela
    Rio, Catherine
    Tyteca, Sophie
    Inter-model comparison of subseasonal tropical variability in aquaplanet experiments: Effect of a warm pool2016In: Journal of Advances in Modeling Earth Systems, ISSN 1942-2466, Vol. 8, no 4, p. 1526-1551Article in journal (Refereed)
  • 248. Lind, Petter
    et al.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Investigation of the Water and Energy Budgets in the BALTEX Area, as Simulated in a Regional Climate Model2007Conference paper (Other academic)
  • 249.
    Lind, Petter
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Temperature and precipitation changes in Sweden; a wide range of model-based projections for the 21st century2008Report (Other academic)
    Abstract [en]

    In this report we analyze the climate change signal for Sweden in scenarios for the 21st century in a large number of coupled atmosphere-ocean general circulation models (AOGCMs), used in the fourth assessment report by the Intergovernmental Panel on Climate Change (IPCC). We focus on near-surface temperature and precipitation. The analysis includes six emission scenarios as well as multi-member runs with the AOGCMs. At the Rossby Centre, SMHI, regional climate models have been run under different emission scenarios and driven by a few AOGCMs. The results of those runs have been used as a basis in climate change, impact and adaptation assessments. Here, we evaluate results from these regional climate model runs in relation to the climate change signal of the IPCC AOGCMs. First, simulated conditions for the recent past (1961-1990) are evaluated. Generally, most AOGCMs tend to have a cold bias for Sweden, especially in winter that can be as large as 10°C. Also, the coarse resolution of the AOGCMs leads to biases in simulated precipitation, both in averages, extremes and often also in the phase of the seasonal cycle. Generally, AOGCMs overestimate precipitation in winter; biases reach 30-40% or even more. In summer, some AOGCMs overestimate precipitation while others underestimate it. Projected responses depend on season and geographical region. Largest signals are seen in winter and in northern Sweden, where the mean simulated temperature increase among the AOGCMs (and across the emissions scenarios B1, A1B and A2) is nearly 6°C by the end of the century, and precipitation increases by around 25%. In southern Sweden, corresponding values are around +4°C and +11%. In summer, the temperature increase is more moderate, which is also the case for precipitation. The regional climate signals are usually within the ranges given by the AOGCM runs, however, the regional models tends to show larger increases in winter, and smaller increases in summertime precipitation.

  • 250.
    Lind, Petter
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Water budget in the Baltic Sea drainage basin: Evaluation of simulated fluxes in a regional climate model2009In: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 14, no 1, p. 56-67Article in journal (Refereed)
    Abstract [en]

    We investigated the Rossby Centre regional climate model, RCA3, and its ability to reproduce the water budget of the Baltic Sea drainage basin during the period from 1979 to 2002. The model was forced on its lateral boundaries with European Centre for Medium-Range Weather Forecasts Re-Analysis data, ERA40. Simulated long-term means and inter-annual variability were compared with observational records and model-derived data. The basin-wide water fluxes were broadly captured by the model, and annual mean net precipitation over land agreed well (i.e., within 5%) with observed total discharge to the Baltic Sea. Long-term annual means of precipitation were around 20% higher in RCA3 compared with reference data, the differences being in most months statistically significant at the 5% level. On the other hand, differences between the reference datasets were evident and in most months also statistically significant. The inclusion of a high-resolution dataset showed a close agreement compared with RCA3; differences were less than 5% in the long-term annual mean. Therefore, more high-resolution observational datasets, especially for evaporation and runoff, are required to refine the water budget and compare water fluxes on sub-regional and local scales.

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