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  • 51.
    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.

  • 52.
    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.

  • 53.
    Lind, Petter
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Lindstedt, David
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Spatial and Temporal Characteristics of Summer Precipitation over Central Europe in a Suite of High-Resolution Climate Models2016In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 29, no 10, p. 3501-3518Article in journal (Refereed)
  • 54.
    Lindstedt, David
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Lind, Petter
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    A new regional climate model operating at the meso-gamma scale: performance over Europe2015In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, article id 24138Article in journal (Refereed)
    Abstract [en]

    There are well-known difficulties to run numerical weather prediction (NWP) and climate models at resolutions traditionally referred to as 'grey-zone' (similar to 3-8 km) where deep convection is neither completely resolved by the model dynamics nor completely subgrid. In this study, we describe the performance of an operational NWP model, HARMONIE, in a climate setting (HCLIM), run at two different resolutions (6 and 15 km) for a 10-yr period (1998-2007). This model has a convection scheme particularly designed to operate in the 'grey-zone' regime, which increases the realism and accuracy of the time and spatial evolution of convective processes compared to more traditional parametrisations. HCLIM is evaluated against standard observational data sets over Europe as well as high-resolution, regional, observations. Not only is the regional climate very well represented but also higher order climate statistics and smaller scale spatial characteristics of precipitation are in good agreement with observations. The added value when making climate simulations at similar to 5 km resolution compared to more typical regional climate model resolutions is mainly seen for the very rare, high-intensity precipitation events. HCLIM at 6 km resolution reproduces the frequency and intensity of these events better than at 15 km resolution and is in closer agreement with the high-resolution observations.

  • 55.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Andréasson, Johan
    SMHI, Professional Services.
    Broman, Barry
    SMHI, Research Department, Climate research - Rossby Centre.
    Graham, Phil
    SMHI, Professional Services.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Persson, Gunn
    SMHI, Professional Services.
    Climate change scenario simulations of wind, sea level, and river discharge in the Baltic Sea and Lake Mälaren region – a dynamical downscaling approach from global to local scales2006Report (Other academic)
    Abstract [en]

    A regional climate model (RCM) and oceanographic, hydrological and digital elevation models were applied to study the impact of climate change on surface wind, sea level, river discharge, and flood prone areas in the Baltic Sea region. The RCM was driven by two global models and two emission scenarios. According to the four investigated regional scenario simulations, wind speed in winter is projected to increase between 3 and 19% as an area average over the Baltic Sea. Although extremes of the wind speed will increase about as much as the mean wind speed, sea level extremes will increase more than the mean sea level, especially along the eastern Baltic coasts. In these areas projected storm events and global average sea level rise may cause an increased risk for flooding. However, the Swedish east coast will be less affected because mainly the west wind component in winter would increase and because land uplift would compensate for increased sea levels, at least in the northern parts of the Baltic. One of the aims of the downscaling approach was to investigate the future risk of flooding in the Lake Mälaren region including Stockholm city. In Stockholm the 100-year surge is projected to change between -51 and 53 cm relative to present mean sea level suggesting that in the city the risk of flooding from the Baltic Sea is relatively small because the critical height of the jetty walls will not be exceeded. Lake Mälaren lies just to the west of Stockholm and flows directly into the Baltic Sea to the east. This study addresses also the question of how the water level in Lake Mälaren may be affected by climate change by incorporating the following three contributing components into an analysis: 1) projected changes to hydrological inflows to Lake Mälaren, 2) changes to downstream water levels in the Baltic Sea, and 3) changes in outflow regulation from the lake. The first component is analyzed using hydrological modeling. The second and third components employ the use of a lake discharge model. An important conclusion is that projected changes to hydrological inflows show a stronger impact on lake levels than projected changes in water level for the Baltic Sea. Furthermore, an identified need for increased outflow capacity from the lake for the present climate does not diminish with projections of future climate change. The tools developed in this work provide valuable inputs to planning for both present and future operations of water level in Lake Mälaren. Based on the oceanographic and hydrological scenario simulations, flood prone areas were analysed in detail for two municipalities, namely Ekerö and Stockholm. The GIS analysis of both municipalities indicates a series of affected areas. However, in case of the 100-year flood (0.65 m above the mean lake level) in present climate or even in case of the maximum probable flood (1.48 m above the mean lake level) the potential risks will be relatively low.

  • 56.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Broman, Barry
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Modelling Sea Level Variability in Different Climates of the Baltic Sea2004In: Fourth Study Conference on BALTEX: Conference Proceedings / [ed] Hans-Jörg Isemer, Risø National Laboratory Technical University of Denmark GKSS Forschungszentrum Geesthacht GmbH , 2004, p. 170-171Conference paper (Other academic)
  • 57.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Broman, Barry
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Simulated sea level in past and future climates of the Baltic Sea2004In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 27, no 1, p. 59-75Article in journal (Refereed)
    Abstract [en]

    Sea levels of the Baltic Sea in past and future climates were investigated based upon 6-hourly regional model results. For the future climate, the Rossby Centre Atmosphere Ocean model was used to perform a set of 30 yr time slice experiments. For each of the 2 driving global models HadAM3H and ECHAM4/OPYC3, one control run (1961 to 1990) and 2 scenario runs (2071 to 2100) based upon the scenarios A2 and B2 of the Special Report on Emission Scenarios (SRES) were conducted. To estimate uncertainties in the global and regional models, 3 sea level scenarios for the Baltic Sea were compiled assuming global average sea level rises between 0.09 and 0.88 m and considering land uplift and the impact of regional changes in wind direction and velocity from the time slice experiments. In the scenarios forced with ECHAM4/OPYC3 the mean sea level between October and April increases significantly compared to the control climate, and storm surges increase even more than monthly mean sea level. In the scenarios forced with HadAM3H the changes are mostly not significant. Depending on the sea level rise, the risk of flooding at the coasts may either decrease in the entire Baltic, or it may increase, especially at the eastern ends of the Gulf of Finland and Gulf of Riga and in Gdansk Bay. Here, maximum changes of about 1 m are found in the winter mean 99% quantiles of the sea level. For the past climate the regional ocean model was forced with reconstructed surface wind fields for 1903 to 1998. The results are close to observations, but storm surges in the western Baltic are underestimated.

  • 58.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Ole Bössing
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Lorenz, Philip
    Rockel, Burkhardt
    Zorita, Eduardo
    Selected examples of the added value of regional climate models2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M., 2009, p. 54-55Conference paper (Other academic)
  • 59.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Estimating uncertainties of projected Baltic Sea salinity in the late 21st century2006In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 33, no 15, article id L15705Article in journal (Refereed)
    Abstract [en]

    As the uncertainty of projected precipitation and wind changes in regional climate change scenario simulations over Europe for the late 21st century is large, we applied a multi-model ensemble approach using 16 scenario simulations based upon seven regional models, five global models, and two emission scenarios to gain confidence in projected salinity changes in the Baltic Sea. In the dynamical downscaling approach a regional ocean circulation model and a large-scale hydrological model for the entire Baltic Sea catchment area were used. Despite the uncertainties, mainly caused by global model biases, salinity changes in all projections are either negative or not statistically significant in terms of natural variability.

  • 60.
    Moberg, Anders
    et al.
    Department of Physical Geography and Quaternary Geology, Stockholm University Department of Meteorology, Stockholm University.
    Gouirand, Isabelle
    Department of Physical Geography and Quaternary Geology, Stockholm University .
    Schoning, Kristian
    Department of Physical Geography and Quaternary Geology, Stockholm University .
    Wohlfarth, Barbara
    Department of Physical Geography and Quaternary Geology, Stockholm University.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    de Jong, Rixt
    Department of Quaternary Geology, Lund University.
    Linderholm, Hans
    Department of Earth Sciences, Göteborg University .
    Zorita, Eduardo
    GKSS Research Centre, Geesthacht, Germany.
    Climate in Sweden during the past millennium – Evidence from proxy data, instrumental data and model simulations2006Report (Other academic)
  • 61. Nik, Vahid M.
    et al.
    Kalagasidis, Angela Sasic
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Assessment of hygrothermal performance and mould growth risk in ventilated attics in respect to possible climate changes in Sweden2012In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 55, p. 96-109Article in journal (Refereed)
    Abstract [en]

    Most of the last 20 years in Sweden have been mild and wet compared to the 1961-1990 climate reference period. After a few relatively cold years in the mid-1980s, practically all years have been warmer than the preceding 30 years average. During the indicated period, an increase of moisture-related problems (mould growth) was observed in ventilated attics, a moisture sensitive building part. This work investigates hygrothermal performance of ventilated attics in respect to possible climate change. Hygrothermal simulations of attics were performed numerically in Matlab. Four attic constructions are investigated - a conventional attic and three alternative constructions suggested by practitioners. Simulations were done for the period of 1961-2100 using the weather data of RCA3 climate model. Effects of three different emissions scenarios are considered. Hygrothermal conditions in the attic are assessed using a mould growth model. Based on the results the highest risk of mould growth was found on the north roof of the attic in Gothenburg, Sweden. Results point to increment of the moisture problems in attics in future. Different emissions scenarios do not influence the risk of mould growth inside the attic due to compensating changes in different variables. Assessing the future performance of the four attics shows that the safe solution is to ventilate the attic mechanically, though this solution inevitably requires extra use of electrical energy for running the fan. Insulating roofs of the attic can decrease the condensation on roofs, but it cannot decrease the risk of mould growth considerably, on the wooden roof underlay. (C) 2012 Elsevier Ltd. All rights reserved.

  • 62. Nik, Vahid M.
    et al.
    Kalagasidis, Angela Sasic
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Statistical methods for assessing and analysing the building performance in respect to the future climate2012In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 53, p. 107-118Article in journal (Refereed)
    Abstract [en]

    Global warming and its effects on climate are of great concern. Climate change can affect buildings in different ways. Increased structural loads from wind and water, changes in energy need and decreased moisture durability of materials are some examples of the consequences. Future climate conditions are simulated by global climate models (GCMs). Downscaling by regional climate models (RCMs) provides weather data with suitable temporal and spatial resolutions for direct use in building simulations. There are two major challenges when the future climate data are used in building simulations. The first is to handle and analyse the huge amount of data. The second challenge is to assess the uncertainties in building simulations as a consequence of uncertainties in the future climate data. In this paper two statistical methods, which have been adopted from climatology, are introduced. Applications of the methods are illustrated by looking into two uncertainty factors of the future climate; operating RCMs at different spatial resolutions and with boundary data from different GCMs. The Ferro hypothesis is introduced as a nonparametric method for comparing data at different spatial resolutions. The method is quick and subtle enough to make the comparison. The parametric method of decomposition of variabilities is described and its application in data assessment is shown by considering RCM data forced by different GCMs. The method enables to study data and its variations in different time scales. It provides a useful summary about data and its variations which makes the comparison between several data sets easier. (C) 2012 Elsevier Ltd. All rights reserved.

  • 63.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Evaluation of temperature extremes from an ensemble of transient RCM simulations driven by several AOGCMs2009Conference paper (Other academic)
  • 64.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Changes in daily temperature variability over Europe from an ensemble of RCM simulations driven by several AOGCMs2009Conference paper (Other academic)
  • 65.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Changes in daily temperature variability over Europe from an ensemble of regional climate simulations driven by several AOGCMs.2009Conference paper (Other academic)
  • 66.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Intraseasonal temperature variability over Europe in a future climate scenario2008In: Abstracts of the contributions of the EGU General Assembly 2008., 2008, Vol. 10, article id EGU2008-A-09248Conference paper (Other academic)
  • 67.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Projected changes in daily temperature variability over Europe in an ensemble of RCM simulations2009Conference paper (Other academic)
  • 68.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    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.
    Nordic weather extremes as simulated by the Rossby Centre Regional Climate Model: model evaluation and future projections2010Conference paper (Other academic)
  • 69.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    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.
    European weather extremes as simulated by the Rossby Centre Regional Climate Model2010In: Geophysical Research Abstracts, 2010, Vol. 12, article id EGU2010-4204Conference paper (Refereed)
  • 70.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    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.
    Evaluation and future projections of temperature, precipitation and wind extremes over Europe in an ensemble of regional climate simulations2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, no 1, p. 41-55Article in journal (Refereed)
  • 71.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Uncertainties in the projected climate changes of wind extremes over the Baltic region2010Conference paper (Other academic)
  • 72.
    Nikulin, Grigory
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Lennard, Chris
    Dosio, Alessandro
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Chen, Youmin
    Haensler, Andreas
    Kupiainen, Marco
    SMHI, Research Department, Climate research - Rossby Centre.
    Laprise, Rene
    Mariotti, Laura
    Maule, Cathrine Fox
    van Meijgaard, Erik
    Panitz, Hans-Juergen
    Scinocca, John F.
    Somot, Samuel
    The effects of 1.5 and 2 degrees of global warming on Africa in the CORDEX ensemble2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 065003Article in journal (Refereed)
  • 73. Näslund, J-O
    et al.
    Wohlfarth, B
    Alexandersson, H
    Helmens, K
    Hättestrand, M
    Jansson, P
    Kleman, J
    Lundqvist, J
    Brandefelt, J
    Houmark-Nielsen, M
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Knudsen, K.L
    Krog Larsen, N
    Ukkonen, P
    Mangerud, J
    Fennoscandian paleo-environment and ice sheet dynamics during Marine Isotope Stage (MIS) 32007Report (Other academic)
  • 74.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Graham, Phil
    SMHI, Professional Services.
    Rosberg, Jörgen
    SMHI, Research Department, Hydrology.
    Hellström, Sara-Sofia
    SMHI, Research Department, Hydrology.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Berndtsson, Ronny
    Lund University, Department of Water Resources Engineering, .
    Simulation of Runoff in the Baltic Sea Drainage Basin During the Past Millennium2007Conference paper (Other academic)
  • 75.
    Persson, Gunn
    et al.
    SMHI, Professional Services.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Climate indices for vulnerability assessments2007Report (Other academic)
    Abstract [en]

    The demand is growing for practical information on climate projections and the impacts expected in different geographical regions and different sectors. It is a challenge to transform the vast amount of data produced in climate models into relevant information for climate change impact studies. Climate indices based on climate model data can be used as means to communicate climate change impact relations. In this report a vast amount of results is presented from a multitude of indices based on different regional climate scenarios.The regional climate scenarios described in this report show many similarities with previous scenarios in terms of general evolution and amplitude of future European climate change. The broad features are manifested in increases in warm and decreases in cold indices. Likewise are presented increases in wet indices in the north and dry indices in the south.Despite the extensive nature of the material presented, it does not cover the full range of possible climate change. We foresee a continued interactive process with stakeholders as well as continued efforts and updates of the results presented in the report.

  • 76.
    Persson, Gunn
    et al.
    SMHI, Professional Services.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Beräknade temperaturförhållanden för tre platser i Sverige – perioderna 1961-1990 och 2011-20402007Report (Other academic)
    Abstract [sv]

    Under hösten 2006 utförde Rossby Centre ett omfattande arbete för att till olika sektorer i samhället ta fram underlagsmaterial om klimatets utveckling. Beställare var framförallt Klimat- och sårbarhetsutredningens olika arbetsgrupper men också energibranschen. Föreliggande rapport beskriver en delleverans till Elforsk-projektet ”Tänkbara konsekvenser för den svenska energisektorn av klimatförändringar – effekter, sårbarhet och anpassning”. Material togs fram som belyser en möjlig temperaturutveckling i ett relativt kort framtidsperspektiv representerat av perioden 2011-2040. Det fanns önskemål om att särskilt titta på utvecklingen för tre platser med olika klimat i ett nord-sydligt perspektiv och med närhet till större befolkningsgrupper.Analyserna inom projektet har finansierats av Elforsk. Modellsimuleringarna har gjorts på den dedikerade klimatdatorresursen ”Tornado” vid Nationellt Superdatorcentrum, Linköpings universitet. Tornado finansieras av Knut och Alice Wallenbergs Stiftelse.I denna rapport presenteras materialet avseende de tre platserna kompletterat med ett litet urval kartor som visar några temperaturindex. Ett mycket omfattande kartmaterial finns att tillgå på Rossby Centrets hemsida som nås via www.smhi.se.

  • 77. Prein, A. F.
    et al.
    Gobiet, A.
    Truhetz, H.
    Keuler, K.
    Goergen, K.
    Teichmann, C.
    Maule, C. Fox
    van Meijgaard, E.
    Deque, M.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Vautard, R.
    Colette, A.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jacob, D.
    Precipitation in the EURO-CORDEX 0.11 degrees and 0.44 degrees simulations: high resolution, high benefits?2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 1-2, p. 383-412Article in journal (Refereed)
    Abstract [en]

    In the framework of the EURO-CORDEX initiative an ensemble of European-wide high-resolution regional climate simulations on a 0.11 degrees (similar to 12.5 km) grid has been generated. This study investigates whether the fine-gridded regional climate models are found to add value to the simulated mean and extreme daily and sub-daily precipitation compared to their coarser-gridded 0.44 degrees (similar to 50 km) counterparts. Therefore, pairs of fine-and coarse-gridded simulations of eight reanalysis-driven models are compared to fine-gridded observations in the Alps, Germany, Sweden, Norway, France, the Carpathians, and Spain. A clear result is that the 0.11 degrees simulations are found to better reproduce mean and extreme precipitation for almost all regions and seasons, even on the scale of the coarser-gridded simulations (50 km). This is primarily caused by the improved representation of orography in the 0.11 degrees simulations and therefore largest improvements can be found in regions with substantial orographic features. Improvements in reproducing precipitation in the summer season appear also due to the fact that in the fine-gridded simulations the larger scales of convection are captured by the resolved-scale dynamics. The 0.11 degrees simulations reduce biases in large areas of the investigated regions, have an improved representation of spatial precipitation patterns, and precipitation distributions are improved for daily and in particular for 3 hourly precipitation sums in Switzerland. When the evaluation is conducted on the fine (12.5 km) grid, the added value of the 0.11 degrees models becomes even more obvious.

  • 78. Pryor, S. C.
    et al.
    Barthelmie, R. J.
    Clausen, N. E.
    Drews, M.
    MacKellar, N.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Analyses of possible changes in intense and extreme wind speeds over northern Europe under climate change scenarios2012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 38, no 1-2, p. 189-208Article in journal (Refereed)
    Abstract [en]

    Dynamical downscaling of ECHAM5 using HIRHAM5 and RCA3 for a northern European domain focused on Scandinavia indicates sustained extreme wind speeds with long recurrence intervals (50 years) and intense winds are not likely to evolve out of the historical envelope of variability until the end of C21st. Even then, significant changes are indicated only in the SW of the domain and across the central Baltic Sea where there is some evidence for relatively small magnitude increases in the 50 year return period wind speed (of up to 15%). There are marked differences in results based on the two Regional Climate Models. Additionally, internal (inherent) variability and initial conditions exert a strong impact on projected wind climates throughout the twenty-first century. Simulations of wind gusts by one of the RCMs (RCA3) indicate some evidence for increased magnitudes (of up to +10%) in the southwest of the domain and across the central Baltic Sea by the end of the current century. As in prior downscaling of ECHAM4, dynamical downscaling of ECHAM5 indicates a tendency towards increased energy density and thus wind power generation potential over the course of the C21st. However, caution should be used in interpreting this inference given the high degree of wind climate projection spread that derives from the specific AOGCM and RCM used in the downscaling.

  • 79. Pryor, S C
    et al.
    Barthelmie, R J
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Potential climate change impact on wind energy resources in northern Europe: analyses using a regional climate model2005In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 25, no 7-8, p. 815-835Article in journal (Refereed)
    Abstract [en]

    There is considerable interest in the potential impact of climate change on the feasibility and predictability of renewable energy sources including wind energy. This paper presents dynamically downscaled near-surface wind fields and examines the impact of climate change on near-surface flow and hence wind energy density across northern Europe. It is shown that: Simulated wind fields from the Rossby Centre coupled Regional Climate Model (RCM) (RCAO) with boundary conditions derived from ECHAM4/OPYC3 AOGCM and the HadAM3H atmosphere-only GCM exhibit reasonable and realistic features as documented in reanalysis data products during the control period (1961-1990). The near-surface wind speeds calculated for a climate change projection period of 2071-2100 are higher than during the control run for two IPCC emission scenarios (A2, B2) for simulations conducted using boundary conditions from ECHAM4/OPYC3. The RCAO simulations conducted using boundary conditions from ECHAM4/OPYC3 indicate evidence for a small increase in the annual wind energy resource over northern Europe between the control run and climate change projection period and for more substantial increases in energy density during the winter season. However, the differences between the RCAO simulations for the climate projection period and the control run are of similar magnitude to differences between the RCAO fields in the control period and the NCEP/NCAR reanalysis data. Additionally, the simulations show a high degree of sensitivity to the boundary conditions, and simulations conducted using boundary conditions from HadAM3H exhibit evidence of slight declines or no change in wind speed and energy density between 1961-1990 and 2071-2100. Hence, the uncertainty of the projected wind changes is relatively high.

  • 80. Pryor, S.C.
    et al.
    Barthelmie, R.J.
    Schoof, J.T.
    Clausen, N.E.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Drews, M.
    Intense and extreme wind speeds over the Nordic countries2010Conference paper (Other academic)
  • 81. Pryor, S.C.
    et al.
    Barthelmie1, R.J.
    Claussen, N.E.
    Nielsen, N.M.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Drews, M.
    Climate change impacts on extreme wind speeds2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M, 2009, p. 271-272Conference paper (Other academic)
  • 82. Refsgaard, J. C.
    et al.
    Madsen, H.
    Andreassian, V.
    Arnbjerg-Nielsen, K.
    Davidson, T. A.
    Drews, M.
    Hamilton, D. P.
    Jeppesen, E.
    Kjellstrom, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Olesen, J. E.
    Sonnenborg, T. O.
    Trolle, D.
    Willems, P.
    Christensen, J. H.
    A framework for testing the ability of models to project climate change and its impacts2014In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 122, no 1-2, p. 271-282Article in journal (Refereed)
    Abstract [en]

    Models used for climate change impact projections are typically not tested for simulation beyond current climate conditions. Since we have no data truly reflecting future conditions, a key challenge in this respect is to rigorously test models using proxies of future conditions. This paper presents a validation framework and guiding principles applicable across earth science disciplines for testing the capability of models to project future climate change and its impacts. Model test schemes comprising split-sample tests, differential split-sample tests and proxy site tests are discussed in relation to their application for projections by use of single models, ensemble modelling and space-time-substitution and in relation to use of different data from historical time series, paleo data and controlled experiments. We recommend that differential-split sample tests should be performed with best available proxy data in order to build further confidence in model projections.

  • 83. Rodhe, H
    et al.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Gallardo, L
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Global scale transport of acidifying pollutants1995In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 85, no 1, p. 37-50Article in journal (Refereed)
    Abstract [en]

    During the past few years several attempts have been made to use three-dimensional tracer transport models to simulate the global distribution of sulfur and nitrogen compounds from both natural and anthropogenic sources. We review these studies and show examples of estimated distributions of the total deposition of sulfur, oxidized nitrogen and ammonium as well as the pH of precipitation. The simulated patterns are compared with observations. Weaknesses in these estimates resulting from lack of knowledge of emissions, chemical transformations and removal processes are emphasized and discussed. We also show examples of how the models can be used to estimate past and future deposition patterns. In particular, we use the IPCC scenario IS92a to estimate the possible sulfur deposition around the world in the year 2050. A comparison with critical load values for sulfur deposition indicates that substantial parts of South and East Asia are at risk for acidification problems in the future.

  • 84.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Ruosteenoja, K
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Impacts of Climate Change on Renewable Energy Sources: Their role in the Nordic energy system: A comprehensive report resulting from a Nordic Energy Research project2007Report (Other academic)
  • 85.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Gollvik, Stefan
    SMHI, Research Department, Meteorology.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Jansson, Christer
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    The Rossby Centre Regional Climate model RCA3: model description and performance2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, no 1, p. 4-23Article in journal (Refereed)
  • 86.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Gollvik, Stefan
    SMHI, Research Department, Meteorology.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    The Rossby Centre Regional Climate Model RCA3: Model description and performance2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63A, no 1, p. 4-23Article in journal (Refereed)
  • 87.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Applying the Rossby Centre Regional Climate Model (RCA3.5) over the ENSEMBLES-AMMA region: Sensitivity studies and future scenarios2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M., 2009, p. 217-218Conference paper (Other academic)
  • 88.
    Schimanke, Semjon
    et al.
    SMHI, Research Department, Oceanography.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    A regional climate model simulation over the Baltic Sea region for the last Millennium2011Report (Other academic)
    Abstract [en]

    Variability and long-term climate change in Fennoscandia is investi-gated in a 1000-year long climate model simulation. We use the Rossby Centre Regional Climate model (RCA3) with boundaryconditions from a General Circulation Model (GCM). Solar variability, changes in orbital parameters and changes in greenhouse gases over the last millennium are used to force the climate models. It is shown that RCA3 generates a warm period corresponding to the Medieval Climate Anomaly (MCA) being the warmest period within the millennium apart from the 20th century. Moreover, an analogy forthe Little Ice Age (LIA) was shown to be the coldest period. The simulated periods are 1100-1299 A.D. for the MCA and 1600-1799 A.D. for the LIA, respectively. This is in agreement with recon-structions and mostly related to changes in the solar irradiance. We found that multi decadal variability has an important impact on the appearance of the MCA and LIA. Moreover, multi decadal variability mayhelp to explain sometimes contradicting reconstructions if these are representative for relatively short non-overlapping periods. In addition to time series, we investigate spatial patterns of temperature, sealevel pressure, precipitation, cloud cover, wind speed and gustiness for annual and seasonal means. Most parameters show the clearest response for the winter season. For instance, winter during the MCAare 1-2.5 K warmer than during the LIA for multi decadal averages.

  • 89.
    Schimanke, Semjon
    et al.
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    The climate in the Baltic Sea region during the last millennium simulated with a regional climate model2012In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 8, no 5, p. 1419-1433Article in journal (Refereed)
    Abstract [en]

    Variability and long-term climate change in the Baltic Sea region is investigated for the pre-industrial period of the last millennium. For the first time dynamical down-scaling covering the complete millennium is conducted with a regional climate model in this area. As a result of changing external forcing conditions, the model simulation shows warm conditions in the first centuries followed by a gradual cooling until ca. 1700 before temperature increases in the last centuries. This long-term evolution, with a Medieval Climate Anomaly (MCA) and a Little Ice Age (LIA), is in broad agreement with proxy-based reconstructions. However, the timing of warm and cold events is not captured at all times. We show that the regional response to the global climate anomalies is to a strong degree modified by the large-scale circulation in the model. In particular, we find that a positive phase of the North Atlantic Oscillation (NAO) simulated during MCA contributes to enhancing winter temperatures and precipitation in the region while a negative NAO index in the LIA reduces them. In a second step, the regional ocean model (RCO-SCOBI) is used to investigate the impact of atmospheric changes onto the Baltic Sea for two 100 yr time slices representing the MCA and the LIA. Besides the warming of the Baltic Sea, the water becomes fresher at all levels during the MCA. This is induced by increased runoff and stronger westerly winds. Moreover, the oxygen concentrations in the deep layers are slightly reduced during the MCA. Additional sensitivity studies are conducted to investigate the impact of even higher temperatures and increased nutrient loads. The presented experiments suggest that changing nutrient loads may be more important determining oxygen depletion than changes in temperature or dynamic feedbacks.

  • 90. Sorland, Silje Lund
    et al.
    Schar, Christoph
    Luthi, Daniel
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Bias patterns and climate change signals in GCM-RCM model chains2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 7, article id 074017Article in journal (Refereed)
  • 91. Steffens, K.
    et al.
    Larsbo, M.
    Moeys, J.
    Kjellstrom, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jarvis, N.
    Lewan, E.
    Modelling pesticide leaching under climate change: parameter vs. climate input uncertainty2014In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 18, no 2, p. 479-491Article in journal (Refereed)
    Abstract [en]

    Assessing climate change impacts on pesticide leaching requires careful consideration of different sources of uncertainty. We investigated the uncertainty related to climate scenario input and its importance relative to parameter uncertainty of the pesticide leaching model. The pesticide fate model MACRO was calibrated against a comprehensive one-year field data set for a well-structured clay soil in southwestern Sweden. We obtained an ensemble of 56 acceptable parameter sets that represented the parameter uncertainty. Nine different climate model projections of the regional climate model RCA3 were available as driven by different combinations of global climate models (GCM), greenhouse gas emission scenarios and initial states of the GCM. The future time series of weather data used to drive the MACRO model were generated by scaling a reference climate data set (1970-1999) for an important agricultural production area in south-western Sweden based on monthly change factors for 2070-2099. 30 yr simulations were performed for different combinations of pesticide properties and application seasons. Our analysis showed that both the magnitude and the direction of predicted change in pesticide leaching from present to future depended strongly on the particular climate scenario. The effect of parameter uncertainty was of major importance for simulating absolute pesticide losses, whereas the climate uncertainty was relatively more important for predictions of changes of pesticide losses from present to future. The climate uncertainty should be accounted for by applying an ensemble of different climate scenarios. The aggregated ensemble prediction based on both acceptable parameterizations and different climate scenarios has the potential to provide robust probabilistic estimates of future pesticide losses.

  • 92. Steffens, Karin
    et al.
    Jarvis, Nicholas
    Lewan, Elisabet
    Lindstrom, Bodil
    Kreuger, Jenny
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Moeys, Julien
    Direct and indirect effects of climate change on herbicide leaching - A regional scale assessment in Sweden2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 514, p. 239-249Article in journal (Refereed)
    Abstract [en]

    Climate change is not only likely to improve conditions for crop production in Sweden, but also to increase weed pressure and the need for herbicides. This study aimed at assessing and contrasting the direct and indirect effects of climate change on herbicide leaching to groundwater in a major crop production region in south-west Sweden with the help of the regional pesticide fate and transport model MACRO-SE. We simulated 37 out of the 41 herbicides that are currently approved for use in Sweden on-eight major crop types for the 24 most common soil types in the region. The results were aggregated accounting for the fractional coverage of the crop and the area sprayed with a particular herbicide. For simulations of the future, we used projections of five different climate models as model driving data and assessed three different future scenarios: (A) only changes in climate, (B) changes in climate and land-use (altered crop distribution), and (C) changes in climate, land-use, and an increase in herbicide use. The model successfully distinguished between leachable and non-leachable compounds (88% correctly classified) in a qualitative comparison against regional-scale monitoring data. Leaching was dominated by only a few herbicides and crops under current climate and agronomic conditions. The model simulations suggest that the direct effects of an increase in temperature, which enhances degradation, and precipitation which promotes leaching, cancel each other at a regional scale, resulting ifs a slight decrease in leachate concentrations in a future climate. However, the area at risk of groundwater contamination doubled when indirect effects of changes in land-use and herbicide use, were considered. We therefore concluded that it is important to consider the indirect effects of climate change alongside the direct effects and that effective mitigation strategies and strict regulation are required to secure future (drinking) water resources. (C) 2014 Elsevier B.V. All rights reserved.

  • 93.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, J
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Modelling last glacial maximum climate variability with a high resolution regional climate model2008In: Abstracts of the contributions of the EGU General Assembly 2008, 2008, article id EGU2008-A-03244Conference paper (Other academic)
  • 94.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, Jenny
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Smith, Benjamin
    High-resolution regional simulation of last glacial maximum climate in Europe2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, no 1, p. 107-125Article in journal (Refereed)
  • 95.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, Jenny
    KTH, Dept. of Mech.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Smith, Benjamin
    Lund Universitt, Dept. of Physical Geography and Ecosystems Analysis.
    Simulating cold palaeo climate conditions in Europe with a regional climate model2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M., 2009, p. 280-281Conference paper (Other academic)
  • 96.
    Strandberg, Gustav
    et al.
    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.
    Jansson, Christer
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Kupiainen, Marco
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    CORDEX scenarios for Europe from the Rossby Centre regional climate model RCA42015Report (Other academic)
    Abstract [en]

    This report documents Coordinated Regional Downscaling Experiment (CORDEX) climate model simulations at 50 km horizontal resolution over Europe with the Rossby Centre regional atmospheric model (RCA4) for i) a ERA-Interim-driven (ERAINT) simulation used to evaluate model performance in the recent past climate, ii) historical simulations of the recent decades with forcing from nine different global climate models (GCMs) and iii) future scenarios RCP 4.5 and RCP 8.5 forced by the same nine different GCMs. Those simulations represent a subset of all CORDEX simulations produced at the Rossby Centre and a general conclusion drawn at the Rossby Centre is that such large ensembles could not have been produced without the establishment of an efficient production chain as outlined here. The first part of this report documents RCA4 and its performance in a perfect boundary simulation where ERAINT was downscaled. RCA4 is to a large extent replicating the large-scale circulation in ERAINT, but some local biases in mean sea level pressure appear. In general the seasonal cycles of temperature and precipitation are simulated in relatively close agreement to observations. Some biases occur, such as too much precipitation in northern Europe and too little in the south. In winter, there is also too much precipitation in eastern Europe. Temperatures are generally biased low in northern Europe and in the Mediterranean region in winter while overestimated temperatures are seen in southeastern Europe in winter and in the Mediterranean area in summer. RCA4 performs generally well when simulating the recent past climate taking boundary conditions from the GCMs. A large part of the RCA4 simulated climate is attributed to the driving GCMs, but RCA4 creates its own climate inside the model domain and adds details due to higher resolution. All nine downscaled GCMs share problems in their representation of the large-scale circulation in winter. This feature is inherited in RCA4. The biases in large-scale circulation induce some biases in temperature and precipitation in RCA4. The climate change signal in the RCP 4.5 and RCP 8.5 ensembles simulated by RCA4 is very similar to what has been presented previously. Both scenarios RCP 4.5 and RCP 8.5 project Europe to be warmer in the future. In winter the warming is largest in northern Europe and in summer in southern Europe. The summer maximum daily temperature increases in a way similar to summer temperature, but somewhat more in southern Europe. The winter minimum daily temperature in northern Europe is the temperature that changes the most. Precipitation is projected to increase in all seasons in northern Europe and decrease in southern Europe. The largest amount of rainfall per day (and per seven day period) is projected to increase in almost all of Europe and in all seasons. At the same time the longest period without precipitation is projected to be longer in southern Europe. Small changes in mean wind speed are generally projected. There are, however, regions with significant changes in wind. The ensemble approach is a way to describe the uncertainties in the scenarios, but there are other possible ensembles using other models which would give other results. Still, the ensemble used here is found to be similar enough to these other possible ensembles to be representative of the whole set of GCMs. Dynamical downscaling using RCA4 changes the climate change signal, and the ensemble spread is sometimes reduced, but the ensemble of nine RCA4 simulations, using different GCMs, is considered to be representative of the full ensemble. All scenarios agree on a climate change pattern; the amplitude of the change is determined by the choice of scenario. The relative importance of the chosen scenario increases with time.

  • 97.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellstrom, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Poska, A.
    Wagner, S.
    Gaillard, M. -J
    Trondman, A. -K
    Mauri, A.
    Davis, B. A. S.
    Kaplan, J. O.
    Birks, H. J. B.
    Bjune, A. E.
    Fyfe, R.
    Giesecke, T.
    Kalnina, L.
    Kangur, M.
    van der Knaap, W. O.
    Kokfelt, U.
    Kunes, P.
    Latalowa, M.
    Marquer, L.
    Mazier, F.
    Nielsen, A. B.
    Smith, B.
    Seppa, H.
    Sugita, S.
    Regional climate model simulations for Europe at 6 and 0.2 k BP: sensitivity to changes in anthropogenic deforestation2014In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 10, no 2, p. 661-680Article in journal (Refereed)
    Abstract [en]

    This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, similar to 6 and similar to 0.2 k BP in Europe. We apply We apply the Rossby Centre regional climate model RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three alternative descriptions of the past vegetation: (i) potential natural vegetation (V) simulated by the dynamic vegetation model LPJ-GUESS, (ii) potential vegetation with anthropogenic land use (deforestation) from the HYDE3.1 (History Database of the Global Environment) scenario (V + H3.1), and (iii) potential vegetation with anthropogenic land use from the KK10 scenario (V + KK10). The climate model results show that the simulated effects of deforestation depend on both local/regional climate and vegetation characteristics. At similar to 6 k BP the extent of simulated deforestation in Europe is generally small, but there are areas where deforestation is large enough to produce significant differences in summer temperatures of 0.5-1 degrees C. At similar to 0.2 k BP, extensive deforestation, particularly according to the KK10 model, leads to significant temperature differences in large parts of Europe in both winter and summer. In winter, deforestation leads to lower temperatures because of the differences in albedo between forested and unforested areas, particularly in the snow-covered regions. In summer, deforestation leads to higher temperatures in central and eastern Europe because evapotranspiration from unforested areas is lower than from forests. Summer evaporation is already limited in the southernmost parts of Europe under potential vegetation conditions and, therefore, cannot become much lower. Accordingly, the albedo effect dominates in southern Europe also in summer, which implies that deforestation causes a decrease in temperatures. Differences in summer temperature due to deforestation range from -1 degrees C in south-western Europe to +1 degrees C in eastern Europe. The choice of anthropogenic land-cover scenario has a significant influence on the simulated climate, but uncertainties in palaeoclimate proxy data for the two time periods do not allow for a definitive discrimination among climate model results.

  • 98.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Climate Impacts from Afforestation and Deforestation in Europe2019In: Earth Interactions, ISSN 1087-3562, E-ISSN 1087-3562, Vol. 23, no 1, article id 1Article in journal (Refereed)
  • 99. Van den Hurk, B
    et al.
    Hirschi, M
    Schar, C
    Lenderink, G
    Van Meijgaard, E
    Van Ulden, A
    Rockel, B
    Hagemann, S
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, R
    Soil control on runoff response to climate change in regional climate model simulations2005In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 18, no 17, p. 3536-3551Article in journal (Refereed)
    Abstract [en]

    Simulations with seven regional climate models driven by a common control climate simulation of a GCM carried out for Europe in the context of the (European Union) EU-funded Prediction of Regional scenarios and Uncertainties for Defining European Climate change risks and Effects (PRUDENCE) project were analyzed with respect to land surface hydrology in the Rhine basin. In particular, the annual cycle of the terrestrial water storage was compared to analyses based on the 40-yr ECMWF Re-Analysis (ERA-40) atmospheric convergence and observed Rhine discharge data. In addition, an analysis was made of the partitioning of convergence anomalies over anomalies in runoff and storage. This analysis revealed that most models underestimate the size of the water storage and consequently overestimated the response of runoff to anomalies in net convergence. The partitioning of these anomalies over runoff and storage was indicative for the response of the simulated runoff to a projected climate change consistent with the greenhouse gas A2 Synthesis Report on Emission Scenarios (SRES). In particular, the annual cycle of runoff is affected largely by the terrestrial storage reservoir. Larger storage capacity leads to smaller changes in both wintertime and summertime monthly mean runoff. The sustained summertime evaporation resulting from larger storage reservoirs may have a noticeable impact on the summertime surface temperature projections.

  • 100. Vautard, Robert
    et al.
    Gobiet, Andreas
    Sobolowski, Stefan
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Stegehuis, Annemiek
    Watkiss, Paul
    Mendlik, Thomas
    Landgren, Oskar
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Teichmann, Claas
    Jacob, Daniela
    The European climate under a 2 degrees C global warming2014In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 9, no 3, article id 034006Article in journal (Refereed)
    Abstract [en]

    A global warming of 2 degrees C relative to pre-industrial climate has been considered as a threshold which society should endeavor to remain below, in order to limit the dangerous effects of anthropogenic climate change. The possible changes in regional climate under this target level of global warming have so far not been investigated in detail. Using an ensemble of 15 regional climate simulations downscaling six transient global climate simulations, we identify the respective time periods corresponding to 2 degrees C global warming, describe the range of projected changes for the European climate for this level of global warming, and investigate the uncertainty across the multi-model ensemble. Robust changes in mean and extreme temperature, precipitation, winds and surface energy budgets are found based on the ensemble of simulations. The results indicate that most of Europe will experience higher warming than the global average. They also reveal strong distributional patterns across Europe, which will be important in subsequent impact assessments and adaptation responses in different countries and regions. For instance, a North-South (West-East) warming gradient is found for summer (winter) along with a general increase in heavy precipitation and summer extreme temperatures. Tying the ensemble analysis to time periods with a prescribed global temperature change rather than fixed time periods allows for the identification of more robust regional patterns of temperature changes due to removal of some of the uncertainty related to the global models' climate sensitivity.

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