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  • 151. Hovsenius, Gunnar
    et al.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Konsekvenser för vindkraften i Sverige av klimatförändringar2007Rapport (Övrigt vetenskapligt)
  • 152.
    Höglund, Anders
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Broman, Barry
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kriezi, Ekaterini
    SMHI.
    Validation and correction of regionalised ERA-40 wind fields over the Baltic Sea using the Rossby Centre Atmosphere model RCA3.02009Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Surface wind fields from ERA-40 regionalised with the Rossby Centre Atmosphere model RCA3.0 are underestimated. In this report a method for correcting the wind fields is evaluated. The method is based on the empirical linear relationship between gusty winds and mean wind. For the validation observations from 26 automatic stations along the Swedish coasts have been used. We found that the validation of wind over the open sea is difficult due to the impact of land that cannot be resolved properly by the atmospheric model as the horizontal grid resolution amounts to about 25 km. In addition, long homogeneous wind data sets are not available due to a switch from manual to automatic readings during the 1990s. The results show that the correction method improves the frequency distribution of simulated wind speed at most stations. Thus the corrected wind fields may be used to force Baltic Sea models during 1961-2004. However, the suggested correction method should be regarded only as a temporary solution while waiting for improved boundary layer

  • 153. Iqbal, W.
    et al.
    Syed, F. S.
    Sajjad, H.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hannachi, A.
    Mean climate and representation of jet streams in the CORDEX South Asia simulations by the regional climate model RCA42017Ingår i: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 129, nr 1-2, s. 1-19Artikel i tidskrift (Refereegranskat)
  • 154. Jacob, D
    et al.
    Van den Hurk, B J J M
    Andrae, Ulf
    SMHI, Forskningsavdelningen, Meteorologi.
    Elgered, G
    Fortelius, C
    Graham, Phil
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jackson, S D
    Karstens, U
    Kopken, C
    Lindau, R
    Podzun, R
    Rockel, B
    Rubel, F
    Sass, B H
    Smith, R N B
    Yang, X
    A comprehensive model inter-comparison study investigating the water budget during the BALTEX-PIDCAP period2001Ingår i: Meteorology and atmospheric physics (Print), ISSN 0177-7971, E-ISSN 1436-5065, Vol. 77, nr 1-4, s. 19-43Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A comparison of 8 regional atmospheric model systems was carried out for a three-month late summer/early autumn period in 1995 over the Baltic Sea and its catchment area. All models were configured on a common grid using similar surface and lateral boundary conditions, and ran in either data assimilation mode (short term forecasts plus data assimilation), forecast made (short term forecasts initialised daily with analyses) or climate mode (no re-initialisation of model interior during entire simulation period). Model results presented in this paper were generally post processed as daily averaged quantities, separate for land and sea areas when relevant. Post processed output was compared against available analyses or observations of cloud cover, precipitation, vertically integrated atmospheric specific humidity, runoff, surface radiation and near surface synoptic observations. The definition of a common grid and lateral forcing resulted in a high degree of agreement among the participating model results for most cases. Models operated in climate mode generally displayed slightly larger deviations from the observations than the data assimilation or forecast mode integration, but in all cases synoptic events were well captured. Correspondence to near surface synoptic quantities was good. Significant disagreement between model results was shown in particular for cloud cover and the radiative properties, average precipitation and runoff. Problems with choosing appropriate initial soil moisture conditions from a common initial soil moisture field resulted in a wide range of evaporation and sensible heat flux values during the first few weeks of the simulations, but better agreement was shown at later times.

  • 155. Jacob, Daniela
    et al.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Christensen, Ole Bossing
    Christensen, Jens Hesselbjerg
    de Castro, Manuel
    Deque, Michel
    Giorgi, Filippo
    Hagemann, Stefan
    Hirschi, Martin
    Jones, Richard
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Lenderink, Geert
    Rockel, Burkhardt
    Sanchez, Enrique
    Schaer, Christoph
    Seneviratne, Sonia I.
    Somot, Samuel
    van Ulden, Aad
    van den Hurk, Bart
    An inter-comparison of regional climate models for Europe: model performance in present-day climate2007Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 81, s. 31-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The analysis of possible regional climate changes over Europe as simulated by 10 regional climate models within the context of PRUDENCE requires a careful investigation of possible systematic biases in the models. The purpose of this paper is to identify how the main model systematic biases vary across the different models. Two fundamental aspects of model validation are addressed here: the ability to simulate (1) the long-term (30 or 40 years) mean climate and (2) the inter-annual variability. The analysis concentrates on near-surface air temperature and precipitation over land and focuses mainly on winter and summer. In general, there is a warm bias with respect to the CRU data set in these extreme seasons and a tendency to cold biases in the transition seasons. In winter the typical spread (standard deviation) between the models is 1 K. During summer there is generally a better agreement between observed and simulated values of inter-annual variability although there is a relatively clear signal that the modeled temperature variability is larger than suggested by observations, while precipitation variability is closer to observations. The areas with warm (cold) bias in winter generally exhibit wet (dry) biases, whereas the relationship is the reverse during summer (though much less clear, coupling warm (cold) biases with dry (wet) ones). When comparing the RCMs with their driving GCM, they generally reproduce the large-scale circulation of the GCM though in some cases there are substantial differences between regional biases in surface temperature and precipitation.

  • 156. Jacob, Daniela
    et al.
    Petersen, Juliane
    Eggert, Bastian
    Alias, Antoinette
    Christensen, Ole Bossing
    Bouwer, Laurens M.
    Braun, Alain
    Colette, Augustin
    Deque, Michel
    Georgievski, Goran
    Georgopoulou, Elena
    Gobiet, Andreas
    Menut, Laurent
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Haensler, Andreas
    Hempelmann, Nils
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Keuler, Klaus
    Kovats, Sari
    Kroener, Nico
    Kotlarski, Sven
    Kriegsmann, Arne
    Martin, Eric
    van Meijgaard, Erik
    Moseley, Christopher
    Pfeifer, Susanne
    Preuschmann, Swantje
    Radermacher, Christine
    Radtke, Kai
    Rechid, Diana
    Rounsevell, Mark
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Somot, Samuel
    Soussana, Jean-Francois
    Teichmann, Claas
    Valentini, Riccardo
    Vautard, Robert
    Weber, Bjorn
    Yiou, Pascal
    EURO-CORDEX: new high-resolution climate change projections for European impact research2014Ingår i: Regional Environmental Change, ISSN 1436-3798, E-ISSN 1436-378X, Vol. 14, nr 2, s. 563-578Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new high-resolution regional climate change ensemble has been established for Europe within the World Climate Research Program Coordinated Regional Downscaling Experiment (EURO-CORDEX) initiative. The first set of simulations with a horizontal resolution of 12.5 km was completed for the new emission scenarios RCP4.5 and RCP8.5 with more simulations expected to follow. The aim of this paper is to present this data set to the different communities active in regional climate modelling, impact assessment and adaptation. The EURO-CORDEX ensemble results have been compared to the SRES A1B simulation results achieved within the ENSEMBLES project. The large-scale patterns of changes in mean temperature and precipitation are similar in all three scenarios, but they differ in regional details, which can partly be related to the higher resolution in EURO-CORDEX. The results strengthen those obtained in ENSEMBLES, but need further investigations. The analysis of impact indices shows that for RCP8.5, there is a substantially larger change projected for temperature-based indices than for RCP4.5. The difference is less pronounced for precipitation-based indices. Two effects of the increased resolution can be regarded as an added value of regional climate simulations. Regional climate model simulations provide higher daily precipitation intensities, which are completely missing in the global climate model simulations, and they provide a significantly different climate change of daily precipitation intensities resulting in a smoother shift from weak to moderate and high intensities.

  • 157.
    Jansson, Anna
    et al.
    SMHI, Samhälle och säkerhet.
    Persson, Christer
    SMHI, Forskningsavdelningen, Luftmiljö.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    2D meso-scale re-analysis of precipitation, temperature and wind over Europe - ERAMESAN: Time period 1980-20042007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The need for long time series of gridded meteorological data with a fine spatial and temporal resolution has increased in recent years. The requirements for this type of gridded meteorological data fields arise from many different areas of the society, in connection to atmospheric environment studies of air quality and deposition and trends in these parameters, regional climate change, wind energy, hydrological studies etc. The aim of the present project is to investigate the possibility of producing historical, high quality and time consistent, meso-scale re analyses for the whole of Europe regarding precipitation, 2 m temperature and wind for at least 25 years back in time.The MESAN analysis system (Häggmark et al., 2000) at SMHI was chosen as a basis for the reanalysis and the system was adjusted to cover the whole of Europe. In order to find the most appropriate first guess fields to be used in the MESAN system, a pilot study was performed. ERA- 40 data from ECMWF was selected as best possible first guess fields for the re analysis. The performed re-analysis, which is denoted ERAMESAN, includes gridded data covering all Europe with a time resolution of 6 h and a spatial resolution of 0.1º (11 km) in a rotated latitude longitude coordinate system for the time-period 1980-2004. All analyses are archived in GRIB-format and stored on disc at SMHI. The dataset is also available within the EUMETNET optional programme Showcase EUROGRID.A partial validation for the years 1998-2000, using a cross validation procedure with independent observations (5.5% of the total amount of stations), shows an improvement in ERAMESAN compared to the ERA-40 data for all studied parameters with regard to root mean square deviation, mean absolute deviation and mean bias deviation for all seasons. The deviations are roughly of the order of 15% smaller compared to what is obtained from ERA-40. The frequency distribution of large precipitation amounts per day and high wind speeds are substantially better described in ERAMESAN compared to ERA-40. However, the tendency to underestimate the frequency of very large precipitation amounts or high wind speeds, compared to observations, can be seen also for ERAMESAN. It is important to be aware of this limitation when using ERAMESAN data for practical applications concerning evaluation of risks for extreme wind speeds or very large precipitation amounts or in e.g. wind energy studies.

  • 158. Jennings, Eleanor
    et al.
    Allott, Norman
    Pierson, Donald C.
    Schneiderman, Elliot M.
    Lenihan, David
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Taylor, David
    Impacts of climate change on phosphorus loading from a grassland catchment: Implications for future management2009Ingår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 43, nr 17, s. 4316-4326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dynamic modelling was used to quantify the impact of projected climate change, and potential changes in population and land use, on phosphorus (P) export from a sub-catchment in SW Ireland using the Generalised watershed Loading Functions (GWLF) model. Overall the results indicated that the increase in annual total phosphorus loads attributable to climate change was greater than that from either population or land use change, and therefore that future climate variability will pose an increasingly significant threat to the successful long-term implementation of catchment management initiatives. The seasonal pattern in projected P export mirrored changes in streamflow, with higher rates between January and April and lower rates in summer. The potential reduction in export in summer was, however, negated when increases in population were included in simulations. A change in the slurry spreading period from that stipulated in national regulations to the months between April and September could potentially mitigate against future increases in dissolved P export in spring. The results indicate that projected changes in climate should be included when undertaking modelling exercises in support of decision making for catchment management plans. (C) 2009 Elsevier Ltd. All rights reserved.

  • 159. Jeong, Jee-Hoon
    et al.
    Walther, Alexander
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Chen, Deliang
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Diurnal cycle of precipitation amount and frequency in Sweden: observation versus model simulation2011Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, nr 4, s. 664-674Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigated the diurnal cycle of precipitation in Sweden using hourly ground observations for 1996-2008. General characteristics of phase and amplitude for the diurnal cycle of precipitation, both in amount and frequency, were identified. In the warm season (April-September), the 'typical' afternoon (14-16 LST) peaks are dominant over inland Sweden, whereas late night to early morning (04-06 LST) peaks with relatively weak amplitude are discernable in the east coast along the Baltic Sea. The diurnal variation is almost negligible in the cold season (October-March), due to the weak solar radiation at high latitudes. The variations of convective activity forced by solar heating and modulated by geographical characteristics were suggested as primarily factors to invoke the cycles and spatial variation identified. The observed cycle was compared with the cycle simulated by a regional climate model. The model fairly well captures the spatial pattern of the phase of the diurnal cycle. However, the warm season afternoon peak is simulated too early and too uniformly across the stations, associated with too frequent occurrences of convective rainfall events with relatively light intensity. These discrepancies point to the need to improve the convection parametrization and geographic representation of the model.

  • 160. Jerez, Sonia
    et al.
    Tobin, Isabelle
    Vautard, Robert
    Pedro Montavez, Juan
    Maria Lopez-Romero, Jose
    Thais, Francoise
    Bartok, Blanka
    Christensen, Ole Bossing
    Colette, Augustin
    Deque, Michel
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kotlarski, Sven
    van Meijgaard, Erik
    Teichmann, Claas
    Wild, Martin
    The impact of climate change on photovoltaic power generation in Europe2015Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, artikel-id 10014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ambitious climate change mitigation plans call for a significant increase in the use of renewables, which could, however, make the supply system more vulnerable to climate variability and changes. Here we evaluate climate change impacts on solar photovoltaic (PV) power in Europe using the recent EURO-CORDEX ensemble of high-resolution climate projections together with a PV power production model and assuming a well-developed European PV power fleet. Results indicate that the alteration of solar PV supply by the end of this century compared with the estimations made under current climate conditions should be in the range (-14%; +2%), with the largest decreases in Northern countries. Temporal stability of power generation does not appear as strongly affected in future climate scenarios either, even showing a slight positive trend in Southern countries. Therefore, despite small decreases in production expected in some parts of Europe, climate change is unlikely to threaten the European PV sector.

  • 161. Jeworrek, Julia
    et al.
    Wu, Lichuan
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Rutgersson, Anna
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Characteristics of convective snow bands along the Swedish east coast2017Ingår i: Earth System Dynamics, ISSN 2190-4979, E-ISSN 2190-4987, Vol. 8, s. 163-175Artikel i tidskrift (Refereegranskat)
  • 162. Jiang, Xianan
    et al.
    Waliser, Duane E.
    Xavier, Prince K.
    Petch, Jon
    Klingaman, Nicholas P.
    Woolnough, Steven J.
    Guan, Bin
    Bellon, Gilles
    Crueger, Traute
    DeMott, Charlotte
    Hannay, Cecile
    Lin, Hai
    Hu, Wenting
    Kim, Daehyun
    Lappen, Cara-Lyn
    Lu, Mong-Ming
    Ma, Hsi-Yen
    Miyakawa, Tomoki
    Ridout, James A.
    Schubert, Siegfried D.
    Scinocca, John
    Seo, Kyong-Hwan
    Shindo, Eiki
    Song, Xiaoliang
    Stan, Cristiana
    Tseng, Wan-Ling
    Wang, Wanqiu
    Wu, Tongwen
    Wu, Xiaoqing
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Zhang, Guang J.
    Zhu, Hongyan
    Vertical structure and physical processes of the Madden-Julian oscillation: Exploring key model physics in climate simulations2015Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 120, nr 10, s. 4718-4748Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aimed at reducing deficiencies in representing the Madden-Julian oscillation (MJO) in general circulation models (GCMs), a global model evaluation project on vertical structure and physical processes of the MJO was coordinated. In this paper, results from the climate simulation component of this project are reported. It is shown that the MJO remains a great challenge in these latest generation GCMs. The systematic eastward propagation of the MJO is only well simulated in about one fourth of the total participating models. The observed vertical westward tilt with altitude of the MJO is well simulated in good MJO models but not in the poor ones. Damped Kelvin wave responses to the east of convection in the lower troposphere could be responsible for the missing MJO preconditioning process in these poor MJO models. Several process-oriented diagnostics were conducted to discriminate key processes for realistic MJO simulations. While large-scale rainfall partition and low-level mean zonal winds over the Indo-Pacific in a model are not found to be closely associated with its MJO skill, two metrics, including the low-level relative humidity difference between high- and low-rain events and seasonal mean gross moist stability, exhibit statistically significant correlations with the MJO performance. It is further indicated that increased cloud-radiative feedback tends to be associated with reduced amplitude of intraseasonal variability, which is incompatible with the radiative instability theory previously proposed for the MJO. Results in this study confirm that inclusion of air-sea interaction can lead to significant improvement in simulating the MJO.

  • 163. Jiao, Yanjun
    et al.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Comparison Studies of Cloud- and Convection-Related Processes Simulated by the Canadian Regional Climate Model over the Pacific Ocean2008Ingår i: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 136, nr 11, s. 4168-4187Artikel i tidskrift (Refereegranskat)
  • 164.
    Joelsson, Rune
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Något om användningen av numeriska prognoser på SMHI (i princip rapporten till ECMWF)1986Rapport (Övrigt vetenskapligt)
  • 165.
    Joelsson, Rune
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    USAs månadsprognoser1986Rapport (Övrigt vetenskapligt)
  • 166. Johansson, Mattias
    et al.
    Galle, Bo
    Zhang, Yan
    Rivera, Claudia
    Chen, Deliang
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    The dual-beam mini-DOAS technique-measurements of volcanic gas emission, plume height and plume speed with a single instrument2009Ingår i: Bulletin of Volcanology, ISSN 0258-8900, E-ISSN 1432-0819, Vol. 71, nr 7, s. 747-751Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The largest error in determining volcanic gas fluxes using ground based optical remote sensing instruments is typically the determination of the plume speed, and in the case of fixed scanning instruments also the plume height. We here present a newly developed technique capable of measuring plume height, plume speed and gas flux using one single instrument by simultaneously collecting scattered sunlight in two directions. The angle between the two measurement directions is fixed, removing the need for time consuming in-field calibrations. The plume height and gas flux is measured by traversing the plume and the plume speed is measured by performing a stationary measurement underneath the plume. The instrument was tested in a field campaign in May 2005 at Mt. Etna, Italy, where the measured results are compared to wind fields derived from a meso-scale meteorological model (MM5). The test and comparison show that the instrument is functioning and capable of estimating wind speed at the plume height.

  • 167.
    Johnston, Sheldon
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Karlsson, Karl-Göran
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    METEOSAT 8 SEVIRI and NOAA AVHRR Cloud Products: A Climate Monitoring SAF2007Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    åtgärder för att minska halka, såsom användning av vinterdäck (med eller utan dubb), sandning och

  • 168.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Development of physical parameterizations for high resolution Climate models2005Ingår i: Extended abstracts of a WMO/WCRP-sponsored Regional-Scale Climate Modelling Workshop. / [ed] Bärring and Laprise, Department of Physical Geography & Ecosystems Analysis Lund University, Sweden , 2005, s. 37-Konferensbidrag (Övrigt vetenskapligt)
  • 169.
    Jones, Colin
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Willen, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    The Rossby Centre Regional Atmospheric Climate Model part 1: Model climatology and performance for the present climate over Europe2004Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, nr 4-5, s. 199-210Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Rossby Centre Atmospheric Regional Climate Model (RCA2) is described and simulation results, for the present climate over Europe, are evaluated against available observations. Systematic biases in the models mean climate and climate variability are documented and key parameterization weaknesses identified. The quality of near-surface parameters is investigated in some detail, particularly temperature, precipitation, the surface energy budget and cloud cover. The model simulates the recent, observed climate and variability with a high degree of realism. Compensating errors in the components of the surface radiation budget are highlighted and the fundamental causes of these biases are traced to the relevant aspects of the cloud, precipitation and radiation parameterizations. The model has a tendency to precipitate too frequently at small rates, this has a direct impact on the simulation of cloud-radiation interaction and surface temperatures. Great care must be taken in the use of observations to evaluate high resolution RCMs, when they are forced by analyzed boundary conditions. This is particularly true with respect to precipitation and cloudiness, where observational uncertainty is often larger than the RCM bias.

  • 170.
    Jones, Colin
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Willen, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    The Rossby Centre regional atmospheric climate model part II: Application to the Arctic climate2004Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, nr 4-5, s. 211-220Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Rossby Centre regional climate model (RCA2) has been integrated over the Arctic Ocean as part of the international ARCMIP project. Results have been compared to observations derived from the SHEBA data set. The standard RCA2 model overpredicts cloud cover and downwelling longwave radiation, during the Arctic winter. This error was improved by introducing a new cloud parameterization, which significantly improves the annual cycle of cloud cover. Compensating biases between clear sky downwelling longwave radiation and longwave radiation emitted from cloud base were identified. Modifications have been introduced to the model radiation scheme that more accurately treat solar radiation interaction with ice crystals. This leads to a more realistic representation of cloud-solar radiation interaction. The clear sky portion of the model radiation code transmits too much solar radiation through the atmosphere, producing a positive bias at the top of the frequent boundary layer clouds. A realistic treatment of the temporally evolving albedo, of both sea-ice and snow, appears crucial for an accurate simulation of the net surface energy budget. Likewise, inclusion of a prognostic snow-surface temperature seems necessary, to accurately simulate near-surface thermodynamic processes in the Arctic.

  • 171. Jonsson, A. M.
    et al.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ensemble analysis of frost damage on vegetation caused by spring backlashes in a warmer Europe2011Ingår i: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 11, nr 2, s. 401-418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Tree dehardening and budburst will occur earlier in a warmer climate, and this could lead to an increased risk of frost damage caused by temperature backlashes. By using a spring backlash index and a cold hardiness model, we assessed different aspects of risk for frost damage in Norway spruce forests during the present climate and for one future emission scenario. Uncertainties associated with climate modelling were quantified by using temperature data from three climate data sets: (1) E-Obs gridded observed climate data, (2) an ensemble of data from eight regional climate models (RCM) forced by ERA-40 reanalysis data, (3) an ensemble of regional climate scenarios produced by the regional climate model RCA3 driven at the boundary conditions by seven global climate models (GCM), all representing the SRES A1B emission scenario. The frost risk was analysed for three periods, 1961-1990, 2011-2040 and 2070-2097. The RCA3 GCM ensemble indicated that the risk for spring frost damage may increase in the boreo-nemoral forest zone of southern Scandinavia and the Baltic states/Belarus. This is due to an increased frequency of backlashes, lower freezing temperatures after the onset of the vegetation period and the last spring frost occurring when the trees are closer to budburst. The changes could be transient due to the fine balance between an increased risk of frost damage caused by dehardening during a period when freezing temperatures are common and a decreased risk caused by warmer temperatures. In the nemoral zone, the zone with highest risk for spring backlashes during the reference period (1961-1990), the spring frost severity may increase due to frost events occurring when the trees are closer to budburst. However, the risk in terms of frequency of backlashes and freezing temperature were projected to become lower already in the beginning of this century.

  • 172. Jonsson, A. M.
    et al.
    Eklundh, L.
    Hellstrom, M.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jonsson, P.
    Annual changes in MODIS vegetation indices of Swedish coniferous forests in relation to snow dynamics and tree phenology2010Ingår i: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 114, nr 11, s. 2719-2730Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Remote sensing provides spatially and temporally continuous measures of forest reflectance, and vegetation indices calculated from satellite data can be useful for monitoring climate change impacts on forest tree phenology. Monitoring of evergreen coniferous forest is more difficult than monitoring of deciduous forest, as the new buds only account for a small proportion of the green biomass, and the shoot elongation process is relatively slow. In this study, we have analyzed data from 186 coniferous monitoring sites in Sweden covering boreal, southern-boreal, and boreo-nemoral conditions. Our objective was to examine the possibility to track seasonal changes in coniferous forests by time-series of MODIS eight-day vegetation indices, testing the coherence between satellite monitored vegetation indices (VI) and temperature dependent phenology. The relationships between two vegetation indices (NDVI and WDRVI) and four phenological indicators (length of snow season, modeled onset of vegetation period, tree cold hardiness level and timing of budburst) were analyzed. The annual curves produced by two curve fitting methods for smoothening of seasonal changes in NDVI and WDRVI were to a large extent characterized by the occurrence of snow, producing stable seasonal oscillations in the northern part and irregular curves with less pronounced annual amplitude in the southern part of the country. Measures based on threshold values of the VI-curves, commonly used for determining the timing of different phenological phases, were not applicable for Swedish coniferous forests. Evergreen vegetation does not have a sharp increase in greenness during spring, and the melting of snow can influence the vegetation indices at the timing of bud burst in boreal forests. However, the interannual variation in VI-values for specific eight-day periods was correlated with the phenological indicators. This relation can be used for satellite monitoring of potential climate change impacts on northern coniferous spring phenology. (C) 2010 Elsevier Inc. All rights reserved.

  • 173. Jonsson, Anna Maria
    et al.
    Appelberg, Gustaf
    Harding, Susanne
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Spatio-temporal impact of climate change on the activity and voltinism of the spruce bark beetle, Ips typographus2009Ingår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 15, nr 2, s. 486-499Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The spruce bark beetle Ips typographus is one of the major insect pests of mature Norway spruce forests. In this study, a model describing the temperature-dependent thresholds for swarming activity and temperature requirement for development from egg to adult was driven by transient regional climate scenario data for Sweden, covering the period of 1961-2100 for three future climate change scenarios (SRES A2, A1B and B2). During the 20th century, the weather supported the production of one bark beetle generation per year, except in the north-western mountainous parts of Sweden where the climate conditions were too harsh. A warmer climate may sustain a viable population also in the mountainous part; however, the distributional range of I. typographus may be restricted by the migration speed of Norway spruce. Modelling suggests that an earlier timing of spring swarming and fulfilled development of the first generation will significantly increase the frequency of summer swarming. Model calculations suggest that the spruce bark beetle will be able to initiate a second generation in South Sweden during 50% of the years around the mid century. By the end of the century, when temperatures during the bark beetle activity period are projected to have increased by 2.4-3.8 degrees C, a second generation will be initiated in South Sweden in 63-81% of the years. The corresponding figures are 16-33% for Mid Sweden, and 1-6% for North Sweden. During the next decades, one to two generations per year are predicted in response to temperature, and the northern distribution limit for the second generation will vary. Our study addresses questions applicable to sustainable forest management, suggesting that adequate countermeasures require monitoring of regional differences in timing of swarming and development of I. typographus, and planning of control operations during summer periods with large populations of bark beetles.

  • 174. Jonsson, Anna Maria
    et al.
    Harding, Susanne
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ravn, Hans Peter
    Impact of climate change on the population dynamics of Ips typographus in southern Sweden2007Ingår i: Agricultural and Forest Meteorology, ISSN 0168-1923, E-ISSN 1873-2240, Vol. 146, nr 1-2, s. 70-81Artikel i tidskrift (Refereegranskat)
  • 175. Jung, Thomas
    et al.
    Doblas-Reyes, Francisco
    Goessling, Helge
    Guemas, Virginie
    Bitz, Cecilia
    Buontempo, Carlo
    Caballero, Rodrigo
    Jakobson, Erko
    Jungclaus, Johann
    Karcher, Michael
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Matei, Daniela
    Overland, James
    Spengler, Thomas
    Yang, Shuting
    POLAR LOWER-LATITUDE LINKAGES AND THEIR ROLE IN WEATHER AND CLIMATE PREDICTION2015Ingår i: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 96, nr 11, s. ES197-ES200Artikel i tidskrift (Refereegranskat)
  • 176. Jungclaus, Johann H.
    et al.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Low-frequency variability of the arctic climate: the role of oceanic and atmospheric heat transport variations2010Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 34, nr 2-3, s. 265-279Artikel i tidskrift (Refereegranskat)
  • 177.
    Jönsson, Anette
    et al.
    SMHI, Samhälle och säkerhet.
    Broman, Barry
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Rahm, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Variations in the Baltic Sea wave fields2003Ingår i: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 30, nr 1, s. 107-126Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The surface waves in the Baltic Sea are hindcast with the spectral wave model HYPAS during a 12-month period. The model results show a strong temporal and spatial variation in the wave field due to the physical dimensions of the different basins and the predominant wind field. The highest waves in the area are found in the outer part of Skagerrak, as well as in the central and southern parts of the Baltic Proper. To get significant waves above 6 m high, strong winds (15-20 m/s) must have been blowing for 6 to 24 h from a favourable direction over a deep area. (C) 2002 Elsevier Science Ltd. All rights reserved.

  • 178. Jönsson, Anna-Maria
    et al.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Future climate impact on spruce bark beetle life cycle in relation to uncertainties in regional climate model data ensembles2011Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, s. 158-173Artikel i tidskrift (Refereegranskat)
  • 179. Kalognomou, Evangelia-Anna
    et al.
    Lennard, Christopher
    Shongwe, Mxolisi
    Pinto, Izidine
    Favre, Alice
    Kent, Michael
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    A Diagnostic Evaluation of Precipitation in CORDEX Models over Southern Africa2013Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 26, nr 23, s. 9477-9506Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The authors evaluate the ability of 10 regional climate models (RCMs) to simulate precipitation over Southern Africa within the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework. An ensemble of 10 regional climate simulations and the ensemble average is analyzed to evaluate the models' ability to reproduce seasonal and interannual regional climatic features over regions of the subcontinent. All the RCMs use a similar domain, have a spatial resolution of 50 km, and are driven by the Interim ECMWF Re-Analysis (ERA-Interim; 1989-2008). Results are compared against a number of observational datasets.In general, the spatial and temporal nature of rainfall over the region is captured by all RCMs, although individual models exhibit wet or dry biases over particular regions of the domain. Models generally produce lower seasonal variability of precipitation compared to observations and the magnitude of the variability varies in space and time. Model biases are related to model setup, simulated circulation anomalies, and moisture transport. The multimodel ensemble mean generally outperforms individual models, with bias magnitudes similar to differences across the observational datasets. In the northern parts of the domain, some of the RCMs and the ensemble average improve the precipitation climate compared to that of ERA-Interim. The models are generally able to capture the dry (wet) precipitation anomaly associated with El Nino (La Nina) events across the region. Based on this analysis, the authors suggest that the present set of RCMs can be used to provide useful information on climate projections of rainfall over Southern Africa.

  • 180. Kamarainen, Matti
    et al.
    Hyvarinen, Otto
    Vajda, Andrea
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    van Meijgaard, Erik
    Teichmann, Claas
    Jacob, Daniela
    Gregow, Hilppa
    Jylha, Kirsti
    Estimates of Present-Day and Future Climatologies of Freezing Rain in Europe Based on CORDEX Regional Climate Models2018Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 123, nr 23, s. 13291-13304Artikel i tidskrift (Refereegranskat)
  • 181.
    Karlsson, Karl-Göran
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Willén, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    USE OF A HIGH-RESOLUTION CLOUD CLIMATE DATA SET FOR VALIDATION OF ROSSBY CENTRE CLIMATE SIMULATIONS2004Ingår i: 2004 EUMETSAT METEOROLOGICAL SATELLITE CONFERENCE: Ocean and Climate Observations, EUMETSAT , 2004, s. 465-473Konferensbidrag (Övrigt vetenskapligt)
  • 182.
    Karlsson, Karl-Göran
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Willen, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Evaluation of regional cloud climate simulations over Scandinavia using a 10-year NOAA advanced very high resolution radiometer cloud climatology2008Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 113, nr D1, artikel-id D01203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A satellite-derived (NOAA Advanced Very High Resolution Radiometer) cloud climatology over the Scandinavian region covering the period 1991 - 2001 has been used to evaluate the performance of cloud simulations of the Swedish Meteorological and Hydrological Institute Rossby Centre regional climate model (RCA3). Several methods of adapting the satellite and model data sets to allow a meaningful comparison were applied. RCA3-simulated total cloud cover was shown to agree within a few percent of the satellite-retrieved cloud amounts on seasonal and annual timescales. However, a substantial imbalance between the respective RCA3 contributions from low-, medium- and high-level clouds was seen. The differences from satellite-derived contributions were +2.4% for high-level clouds, -5.2% for medium-level clouds and +4.0% for low- level clouds. In addition, an overrepresentation of cloud categories with high optical thicknesses was seen for all vertical cloud groups, particularly during the summer season. Some specific features of the geographical distribution of cloudiness were also noticed. Most pronounced were the excess of cloud amounts over the Scandinavian mountain range and a deficit leeward of the mountains. The overall results imply problems with the RCA3-modeled surface radiation budget components by causing reduced incoming solar radiation and increased downwelling longwave radiation.

  • 183. Kendon, Elizabeth J.
    et al.
    Jones, Richard G.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Murphy, James M.
    Using and Designing GCM-RCM Ensemble Regional Climate Projections2010Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 23, nr 24, s. 6485-6503Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multimodel ensembles, whereby different global climate models (GCMs) and regional climate models (RCMs) are combined, have been widely used to explore uncertainties in regional climate projections. In this study, the extent to which information can be enhanced from sparsely filled GCM RCM ensemble matrices and the way in which simulations should be prioritized to sample uncertainties most effectively are examined. A simple scaling technique, whereby the local climate response in an RCM is predicted from the large-scale change in the GCM, is found to often show skill in estimating local changes for missing GCM RCM combinations. In particular, scaling shows skill for precipitation indices (including mean, variance, and extremes) across Europe in winter and mean and extreme temperature in summer and winter, except for hot extremes over central/northern Europe in summer. However, internal variability significantly impacts the ability to determine scaling skill for precipitation indices, with a three-member ensemble found to be insufficient for identifying robust local scaling relationships in many cases. This study suggests that, given limited computer resources, ensembles should be designed to prioritize the sampling of GCM uncertainty, using a reduced set of RCMs. Exceptions are found over the Alps and northeastern Europe in winter and central Europe in summer, where sampling multiple RCMs may be equally or more important for capturing uncertainty in local temperature or precipitation change. This reflects the significant role of local processes in these regions. Also, to determine the ensemble strategy in some cases, notably precipitation extremes in summer, better sampling of internal variability is needed.

  • 184.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Daily variability in temperature and precipitation: Recent and future changes over Europe2005Ingår i: EXTENDED ABSTRACTS of a WMO/WCRP-sponsored REGIONAL-SCALE CLIMATE MODELLING WORKSHOP: HIGH-RESOLUTION CLIMATE MODELLING: ASSESSMENT, ADDED VALUE AND APPLICATIONS / [ed] Lars Bärring & René Laprise, Department of Physical Geography & Ecosystems Analysis Lund University, Sweden , 2005, Vol. 5, s. 72-73Konferensbidrag (Övrigt vetenskapligt)
  • 185.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Evaluating regional climate model simulations of daily maximum and minimum temperatures in the ENSEMBLES project2008Ingår i: Abstracts of the contributions of the EGU General Assembly 2008, 2008, Vol. 10, artikel-id EGU2008-A-02262Konferensbidrag (Övrigt vetenskapligt)
  • 186.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Present-Day and Future Precipitation in the Baltic Region as Simulated in Regional Climate Models2004Ingår i: Fourth Study Conference on BALTEX: Conference Proceedings / [ed] Hans-Jörg Isemer, Risø National Laboratory Technical University of Denmark GKSS Forschungszentrum Geesthacht GmbH , 2004, s. 170-171Konferensbidrag (Övrigt vetenskapligt)
  • 187.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Recent and future signatures of climate change in Europe2004Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, nr 4-5, s. 193-198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A set of six regional climate model experiments is investigated for future changes in daily temperature and precipitation in Europe. Changes in the probability distributions for these variables are studied. It is found that the asymmetry of these distributions change differently depending on location and season. Large summertime changes in extremely high temperatures in central, eastern and southern Europe are followed by higher than average temperature increases on warm days in general. Likewise, temperatures on cold days increase much more than the average temperature increase during winter in eastern and northern Europe. A comparison with historical data on wintertime temperature shows that the model simulated and observed daily variability are similar. In particular, the much stronger increase in temperatures on cold days, compared to the average temperature increase as observed in warm compared to cold historical periods, is simulated also by the model. The contribution from heavy precipitation events is simulated to increase over most parts of Europe in all seasons.

  • 188.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Abrahamsson, Reino
    Naturvårdsverket.
    Boberg, Pelle
    Naturvårdsverket.
    Jernbäcker, Eva
    Naturvårdsverket.
    Karlberg, Marie
    Energimyndigheten.
    Morel, Julien
    Energimyndigheten.
    Uppdatering av det klimatvetenskapliga kunskapsläget2014Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det klimatvetenskapliga kunskapsläget har förstärkts ytterligare under senare år. IPCC:s utvärderingsrapporter utgör de mest omfattande synteserna som finns på området. Huvudbudskapen i den senaste utvärderingsrapporten (AR5) är i allt väsentligt i linje med föregående rapport, även om ny kunskap har tillkommit och tidigare kunskap fördjupats.Uppvärmningen av klimatsystemet har fortsatt och människans påverkan är tydligSäkerheten i slutsatsen att människan påverkar klimatet har successivt stärkts i varje ny utvärderingsrapport från IPCC. Till de observerade förändringarna i klimatet hör att den lägre atmosfären och haven blivit varmare, nederbördsmönster ändrats, snötäckets utbredning på norra halvklotet liksom utbredningen av Arktis havsis har minskat. Som följd av uppvärmningen minskar också istäcket på Grönland och Antarktis samtidigt som många glaciärer smälter vilket bidrar till den stigande havsnivån. De ökade halterna av växthusgaser i atmosfären, främst koldioxid till följd av människans utsläpp, påverkar jordens strålningsbalans och är den främsta orsaken till den snabba uppvärmningen.Vi står inför fortsatt kraftig klimatförändring med allvarliga konsekvenserHur stor den framtida klimatförändringen blir beror på graden av ändrad strålningsbalans samt på klimatsystemets respons. Av de klimatscenarier som presenteras i AR5 är det bara i scenariot med minst klimatpåverkan som ökningen av den globala medel-temperaturen sannolikt inte kommer att överstiga 2°C jämfört med förindustriella nivåer. I ett scenario med nuvarande politik kan temperaturöverskridandet bli över 4°C och havsytans medelnivå höjas med uppemot en meter, eller möjligen mer, till år 2100. Generellt förväntas nederbörden öka där det redan regnar mycket och minska där det är torrt. Förekomsten av extrema väderhändelser förväntas också öka. Följdeffekterna inkluderar mer översvämningar och torka, och därigenom större risk för spridning av sjukdomar, brist på rent vatten och skördebortfall.Klimatförändringar drabbar redan utsatta värst, men Sverige påverkas också negativtFramtida klimatförändringar väntas innebära en rad negativa effekter för människor, samhällen och ekosystem. Dessa effekter blir mer kännbara vid högre grad av klimatpåverkan. IPCC slår fast att ytterligare uppvärmning ger en ökad sannolikhet för allvarliga, genomträngande och bestående effekter. Detta rör t.ex. hotade ekosystem i stora delar av världen där många arter kan komma att utrotas, kustnära samhällen som hotas av havsnivåhöjning och negativ påverkan på livsmedelsförsörjning. Även sekundära effekter som försvårande av fattigdomsbekämpning och ökad risk för skärpta konflikter i redan utsatta delar av världen pekas på som risker för samhället.Sveriges klimat har blivit varmare och mer nederbördsrikt. Fortsatta förändringar är att vänta och även om den globala medeltemperaturökningen begränsas till under 2 °C väntas kraftiga förändringar som kan komma att påverka samhället och naturmiljön. Skyfall och kraftiga regn förväntas öka i intensitet vilket kan ge ökade problem med översvämningar. Översvämningar kan också komma att drabba låglänta kusttrakter i södra Sverige p.g.a. stigande havsnivåer. Uppvärmningen väntas få konsekvenser för jord- och skogsbruk och även för naturliga ekosystem, inte minst i fjällkedjan där trädgränsen förväntas flytta högre upp i terrängen.Om vi agerar kraftfullt kan den globala temperaturökningen fortfarande begränsas till under 2 °CVärldens utsläpp fortsätter öka snabbt. Utsläppen av koldioxid mellan 1970 och 2010 överskred den sammanlagda mängden som släpptes ut före 1970. Den kraftiga ökningen av utsläppen mellan 2000 och 2010 har främst skett i tillväxtekonomier. Utsläppen bedöms fortsätta öka även i framtiden med dagens beslutade politik och styrmedel.För att "sannolikt" (med mer än 66 procents sannolikhet) begränsa temperaturökningen till under 2 °C år 2100 behöver de globala utsläppen nå sin kulmen inom en snar framtid, minska med 40 till 70 procent till år 2050 och till nära noll eller bli negativa år 2100. En så stor utsläppsreduktion kräver omfattande omställningar världen över i såväl industrialiserade som i snabbt växande ekonomier. Internationellt samarbete och verktyg för att främja utsläppsminskning är därför nödvändiga. För att begränsa effekterna och sårbarheten för de klimatförändringar som uppstår måste åtgärderna för utsläpps-minskningar kompletteras med klimatanpassningsåtgärder.Åtgärder för utsläppsminskning måste sättas in snart och kommer att krävas under mycket lång tidPå kort sikt behöver inlåsningar i koldioxidintensiv och energikrävande teknik och samhällsbyggnad undvikas genom att bygga hållbart från början. En sådan inriktning gör det också enklare att utveckla mer hållbara beteendemönster. Inriktningen är särskilt viktigt i de delar av världen där en stor mängd städer och energianläggningar nu håller på att byggas och expandera men också när tidigt industrialiserade länder nu genomför åter-investeringar i den befintliga bebyggelsen och infrastrukturen.Eftersom energieffektivisering minskar behovet av att tillföra ytterligare energi i systemet visar IPCC:s scenariomodelleringar att omfattande investeringar behöver göras i energi-effektiviserande åtgärder i perioden innan 2030.På lång sikt behöver energi- och resursanvändningen bli mycket mer effektiv än i dag, energitillförseln behöver nå nollutsläpp eller till och med negativa utsläpp och upptaget av koldioxid i skog och mark behöver öka. Ökad tillgång på bioenergi som producerats på ett hållbart sätt är viktigt för att få ner kostnaderna för omställningen. Försenas utsläpps-minskningarna ökar risken för allvarliga klimatförändringar och kostnaderna för klimat-politiken betydligt. IPCC-rapporten visar att ju längre världens länder väntar, desto mer behöver världen förlita sig på en omfattande användning av osäkra tekniker såsom bio-baserade energianläggningar med koldioxidfångning och lagring (bio-CCS) för att kunna åstadkomma negativa utsläpp (upptag av koldioxid från atmosfären) till år 2100.Klimatåtgärder som en del av hållbar utvecklingKlimatåtgärderna kan i många fall leda till positiva synergier med andra samhällsmål t.ex. när åtgärderna även innebär att vi hushåller med energi och vatten, att utsläppen av luft-föroreningar minskar, att det utvecklas ett hållbart jord- och skogsbruk, att energi-fattigdom minskar samt genom att ekosystemtjänster upprätthålls. Samtidigt kan klimat-åtgärder även medföra risker för negativa sidoeffekter, t.ex. om användningen av bioenergi utvecklas i konflikt med livsmedelsproduktion och biodiversitet. IPCC-rapporten betonar därför vikten av att främja de åtgärder som skapar synergier med andra samhällsmål, inklusive anpassning till klimatförändringarna.

  • 189.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Boberg, Fredrik
    Castro, Manuel
    Christensen, Jens Hesselbjerg
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Sanchez, Enrique
    Daily and monthly temperature and precipitation statistics as performance indicators for regional climate models2010Ingår i: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 44, nr 2-3, s. 135-150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We evaluated daily and monthly statistics of maximum and minimum temperatures and precipitation in an ensemble of 16 regional climate models (RCMs) forced by boundary conditions from reanalysis data for 1961-1990. A high-resolution gridded observational data set for land areas in Europe was used. Skill scores were calculated based on the match of simulated and observed empirical probability density functions. The evaluation for different variables, seasons and regions showed that some models were better/worse than others in an overall sense. It also showed that no model that was best/worst in all variables, seasons or regions. Biases in daily precipitation were most pronounced in the wettest part of the probability distribution where the RCMs tended to overestimate precipitation compared to observations. We also applied the skill scores as weights used to calculate weighted ensemble means of the variables. We found that weighted ensemble means were slightly better in comparison to observations than corresponding unweighted ensemble means for most seasons, regions and variables. A number of sensitivity tests showed that the weights were highly sensitive to the choice of skill score metric and data sets involved in the comparison.

  • 190.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Brandefelt, J.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Smith, B
    Wohlfart, B
    Näslund, J-O
    Extreme climate conditions in Sweden in a 100,000 year perspective as simulated by global and regional climate models2009Konferensbidrag (Övrigt vetenskapligt)
  • 191.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Brandefelt, J
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Smith, B
    Wohlfart, B
    Näslund, J-O
    Global and regional climate model simulations of extreme climate conditions in Sweden in a 100,000 year perspective2008Ingår i: Abstracts of the contributions of the EGU General Assembly 2008., 2008, Vol. 10, artikel-id EGU2008-A-02249Konferensbidrag (Övrigt vetenskapligt)
  • 192.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Brandefelt, Jenny
    Naslund, Jens-Ove
    Smith, Ben
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Voelker, Antje H. L.
    Wohlfarth, Barbara
    Simulated climate conditions in Europe during the Marine Isotope Stage 3 stadial2010Ingår i: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 39, nr 2, s. 436-456Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    State-of-the-art climate models were used to simulate climate conditions in Europe during Greenland Stadial (GS) 12 at 44 ka BP. The models employed for these simulations were: (i) a fully coupled atmosphere-ocean global climate model (AOGCM), and (ii) a regional atmospheric climate model (RCM) to dynamically downscale results from the global model for a more detailed investigation of European climate conditions. The vegetation was simulated off-line by a dynamic vegetation model forced by the climate from the RCM. The resulting vegetation was then compared with the a priori vegetation used in the first simulation. In a subsequent step, the RCM was rerun to yield a new climate more consistent with the simulated vegetation. Forcing conditions included orbital forcing, land-sea distribution, ice-sheet configuration, and atmospheric greenhouse gas concentrations representative for 44 ka BP. The results show a cold climate on the global scale, with global annual mean surface temperatures 5 degrees C colder than the modern climate. This is still significantly warmer than temperatures derived from the same model system for the Last Glacial Maximum (LGM). Regional, northern European climate is much colder than today, but still significantly warmer than during the LGM. Comparisons between the simulated climate and proxy-based sea-surface temperature reconstructions show that the results are in broad agreement, albeit with a possible cold bias in parts of the North Atlantic in summer. Given a prescribed restricted Marine Isotope Stage 3 ice-sheet configuration, with large ice-free regions in Sweden and Finland, the AOGCM and RCM model simulations produce a cold and dry climate in line with the restricted ice-sheet configuration during GS 12. The simulated temperature climate, with prescribed ice-free conditions in south-central Fennoscandia, is favourable for the development of permafrost, but does not allow local ice-sheet formation as all snow melts during summer.

  • 193.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Evaluating the method of pattern-scaling in time2006Konferensbidrag (Övrigt vetenskapligt)
  • 194.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Gollvik, Stefan
    Meterologi.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Willén, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    A 140-year simulation of European climate with the new version of the Rossby Centre regional atmospheric climate model (RCA3)2005Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report presents the latest version of the Rossby Centre regional atmospheric model, RCA3, with focus on model improvements since the earlier version, RCA2. The main changes in RCA3 relate to the treatment of land surface processes. Apart from the changes in land surface parameterizations several changes in the calculation of radiation, clouds, condensate and precipitation have been made. The new parameterizations hold a more realistic description of the climate system.Simulated present day climate is evaluated compared to observations. The new model version show equally good, or better, correspondence to observational climatologies as RCA2, when forced by perfect boundary conditions. Seasonal mean temperature errors are generally within ±1oC except during winter in north-western Russia where a larger positive bias is identified. Both the diurnal temperature range and the annual temperature range are found to be underestimated in the model. Precipitation biases are generally smaller than in the corresponding reanalysis data used as boundary conditions, showing the benefit of a higher horizontal resolution.The model is used for the regionalization of two transient global climate change projections for the time period 1961- 2100. The radiative forcing of the climate system is based on observed concentrations of greenhouse gases until 1990 and on the IPCC SRES B2 and A2 emissions scenarios for the remaining time period. Long-term averages as well as measures of the variability around these averages are presented for a number of variables including precipitation and near-surface temperature. It is shown that the changes in variability sometimes differ from the changes in averages. For instance, in north-eastern Europe, the mean increase in wintertime temperatures is followed by an even stronger reduction in the number of very cold days in winter. This kind of performance of the climate system implies that methods of inferring data from climate change projections to other periods than those actually simulated have to be used with care, at least when it comes to variables that are expected to change in a non-linear way. Further, these new regional climate change projections address the whole 21st century.

  • 195.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jacob, Daniela
    Jones, Richard
    Lenderink, Geert
    Schaer, Christoph
    Modelling daily temperature extremes: recent climate and future changes over Europe2007Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 81, s. 249-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Probability distributions of daily maximum and minimum temperatures in a suite of ten RCMs are investigated for (1) biases compared to observations in the present day climate and (2) climate change signals compared to the simulated present day climate. The simulated inter-model differences and climate changes are also compared to the observed natural variability as reflected in some very long instrumental records. All models have been forced with driving conditions from the same global model and run for both a control period and a future scenario period following the A2 emission scenario from IPCC. We find that the bias in the fifth percentile of daily minimum temperatures in winter and at the 95th percentile of daily maximum temperature during summer is smaller than 3 (+/- 5 degrees C) when averaged over most (all) European sub-regions. The simulated changes in extreme temperatures both in summer and winter are larger than changes in the median for large areas. Differences between models are larger for the extremes than for mean temperatures. A comparison with historical data shows that the spread in model predicted changes in extreme temperatures is larger than the natural variability during the last centuries.

  • 196.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nilsson, Carin
    Lunds Universitet.
    Persson, Gunn
    SMHI, Affärsverksamhet.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Production and use of regional climate model projections – A Swedish perspective on building climate services2016Ingår i: Climate Services, ISSN 2405-8807, nr 2-3, s. 15-29Artikel i tidskrift (Refereegranskat)
  • 197.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Atmospheric response to different sea surface temperatures in the Baltic Sea: coupled versus uncoupled regional climate model experiments2005Ingår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 36, nr 4-5, s. 397-409Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A climate change experiment with a fully coupled high resolution regional atmosphere-ocean model for the Baltic Sea is compared to an experiment with a stand-alone regional atmospheric model. Both experiments simulate 30-yr periods with boundary data from the same global climate model system. This particular global model system simulates very high sea surface temperatures during summer for the Baltic Sea at the end of this century under the investigated emission scenario. We show that the sea surface temperatures are less warm in the coupled regional model compared to the global model system and that this difference is dependent on the atmospheric circulation. In summers with a high NAO index and thereby relatively strong westerly flow over the North Atlantic the differences between the two models are small, while in summers with a weaker, more northerly flow over the Baltic Sea the differences are very large. The higher sea surface temperatures in the uncoupled experiment lead to an intensified hydrological cycle over the Baltic Sea, with more than 30% additional precipitation in summer taken as an average over the full 30-yr period and over the entire Baltic Sea. The differences are mostly local, over the sea, but there are differences in surrounding land areas.

  • 198.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Drews, M.
    Christensen, J. H.
    Haugen, J.E.
    Haakenstad, H.
    Shkolnik, I.
    An ensemble of regional climate change scenarios for the nordic countries.2010Konferensbidrag (Övrigt vetenskapligt)
  • 199.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Giorgi, Filippo
    Regional Climate Model evaluation and weighting Introduction2010Ingår i: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 44, nr 2-3, s. 117-119Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    An ensemble of regional climate models downscaling reanalysis data has been evaluated against observations for the time period 1961-2000. Various aspects of model performance including both their representation of large-scale features and their ability to add value on smaller spatial scales have been considered. A set of metrics has been derived and combined into a performance-based weigthing system that is used in the production of probabilistic climate change projections. Strengths and weaknesses of weighting techniques for RCM ensembles are discussed.

  • 200.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Holmen, K
    Eneroth, K
    Engardt, Magnuz
    SMHI, Forskningsavdelningen, Luftmiljö.
    Summertime Siberian CO2 simulations with the regional transport model MATCH: a feasibility study of carbon uptake calculations from EUROSIB data2002Ingår i: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 54, nr 5, s. 834-849Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Biogenic surface fluxes Of CO2 over Europe and Siberia are implemented in the regional tracer transport model MATCH. A systematic comparison between simulated and observed CO2 fluxes and mixing ratios is performed for two observational sites in Russia taking into account both surface observations and vertical profiles of meteorological parameters and CO2 in the lowest 3 km from the summer months in 1998. We find that the model is able to represent meteorological parameters as temperature, humidity and planetary boundary layer height consistent with measurements. Further, it is found that the simulated surface CO2 fluxes capture a large part of the observed variability on a diurnal time scale. On a synoptic time scale the agreement between observations and simulation is poorer which leads to a disagreement between time series of observed and simulated CO2 mixing ratios. However, the model is able to realistically simulate the vertical gradient in CO2 in the lowest few kilometres. The vertical variability is studied by means of trajectory analysis together with results from the MATCH model. This analysis clearly illustrates some problems in deducing CO2 fluxes from CO2 mixing ratios measured in single vertical profiles. Studies of the regional variability Of CO2 in the model domain show that there exists no ideal vertical level for detecting the terrestrial signal Of CO2 in the free troposphere. The strongest terrestrial signal is found in the boundary layer above the lowest few hundred metres. Nevertheless, this terrestrial signal is small, and during the simulated period it is not possible to detect relative variations in the surface fluxes smaller than 20%. We conclude that a regional flux cannot be determined from single ground stations or a few vertical profiles, mainly due to synoptic scale variability in transport and in CO2 surface fluxes.

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