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  • 151. Hazeleger, Wilco
    et al.
    Severijns, Camiel
    Semmler, Tido
    Stefanescu, Simona
    Yang, Shuting
    Wang, Xueli
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Dutra, Emanuel
    Baldasano, Jose M.
    Bintanja, Richard
    Bougeault, Philippe
    Caballero, Rodrigo
    Ekman, Annica M. L.
    Christensen, Jens H.
    van den Hurk, Bart
    Jimenez, Pedro
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Kållberg, Per
    SMHI, Research Department, Meteorology.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    McGrath, Ray
    Miranda, Pedro
    Van Noije, Twan
    Palmer, Tim
    Parodi, Jose A.
    Schmith, Torben
    Selten, Frank
    Storelvmo, Trude
    Sterl, Andreas
    Tapamo, Honore
    Vancoppenolle, Martin
    Viterbo, Pedro
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    EC-Earth A Seamless Earth-System Prediction Approach in Action2010In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 91, no 10, p. 1357-1363Article in journal (Other academic)
  • 152. Hedelin, Beatrice
    et al.
    Evers, Mariele
    Alkan-Olsson, Johanna
    Jonsson, Anna
    SMHI, Core Services.
    Participatory modelling for sustainable development: Key issues derived from five cases of natural resource and disaster risk management2017In: Environmental Science and Policy, ISSN 1462-9011, E-ISSN 1873-6416, Vol. 76, p. 185-196Article in journal (Refereed)
  • 153. Heino, R
    et al.
    Brazdil, R
    Forland, E
    Tuomenvirta, H
    Alexandersson, Hans
    SMHI.
    Beniston, M
    Pfister, C
    Rebetez, M
    Rosenhagen, G
    Rosner, S
    Wibig, J
    Progress in the study of climatic extremes in northern and central Europe1999In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 42, no 1, p. 151-181Article in journal (Refereed)
    Abstract [en]

    A study of the long-term changes of various climatic extremes was made jointly by a number of European countries. It was found that the changes in maximum and minimum temperatures follow, in broad terms, the corresponding well-documented mean temperature changes. Minimum temperatures, however, have increased slightly more than maximum temperatures, although both have increased. As a result, the study confirms that the diurnal temperature range has mostly decreased during the present century in Northern and Central Europe. Frost has become less frequent. Two extreme-related precipitation characteristics, the annual maximum daily precipitation and the number of days with precipitation greater than or equal to 10 mm, show no major trends or changes in their interannual variability. An analysis of return periods indicated that in the Nordic countries there were high frequencies of 'extraordinary' 1-day rainfalls both in the 1930s and since the 1980s. There have been no long-term changes in the number of high wind speeds in the German Eight. Occurrences of thunderstorms and hails show a decreasing tendency in the Czech Republic during the last 50 years. Finally, using proxy data sources, a 500-year temperature and precipitation event graph for the Swiss Mittelland is presented. It shows large interdecadal variations as well as the exceptionality of the latest decade 1986-1995.

  • 154. Hell, Benjamin
    et al.
    Broman, Barry
    SMHI, Research Department, Climate research - Rossby Centre.
    Jakobsson, Lars
    Jakobsson, Martin
    Magnusson, Ake
    Wiberg, Patrik
    The Use of Bathymetric Data in Society and Science: A Review from the Baltic Sea2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 2, p. 138-150Article, review/survey (Refereed)
    Abstract [en]

    Bathymetry, the underwater topography, is a fundamental property of oceans, seas, and lakes. As such it is important for a wide range of applications, like physical oceanography, marine geology, geophysics and biology or the administration of marine resources. The exact requirements users may have regarding bathymetric data are, however, unclear. Here, the results of a questionnaire survey and a literature review are presented, concerning the use of Baltic Sea bathymetric data in research and for societal needs. It is demonstrated that there is a great need for detailed bathymetric data. Despite the abundance of high-quality bathymetric data that are produced for safety of navigation purposes, the digital bathymetric models publicly available to date cannot satisfy this need. Our study shows that DBMs based on data collected for safety of navigation could substantially improve the base data for administrative decision making as well as the possibilities for marine research in the Baltic Sea.

  • 155. Hellstrom, C
    et al.
    Chen, D L
    Achberger, C
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Comparison of climate change scenarios for Sweden based on statistical and dynamical downscaling of monthly precipitation2001In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 19, no 1, p. 45-55Article in journal (Refereed)
    Abstract [en]

    Two dynamically and statistically downscaled precipitation scenarios for Sweden are compared with respect to changes in the mean, The dynamically downscaled scenarios are generated by a 44 km version of the Rossby Centre regional climate model (RCM). The RCM is driven by data from 2 global greenhouse gas simulations sharing a 2.6degreesC global warming, one made by the HadCM2 and the other by the ECHAM4 general circulation model (GCM). The statistical downscaling model driven by the same GCMs is regression-based and incorporates large-scale circulation indices of the 2 geostrophic wind components (u and v), total vorticity (xi) and large-scale humidity at 850 hPa (q850) as predictors. The precipitation climates of the GCMs, RCMs and statistical models from the control runs are compared with respect to their ability to reproduce the observed seasonal cycle. Great improvements in the simulation of the seasonal cycle by all the downscaling models compared to the GCMs significantly increase the credibility of the downscaling models, The precipitation changes produced by the statistical models result from changes in all predictors, but the change in 4 is the greatest contributor in southern Sweden followed by q850 and u, while changes in q850 have greater effects in the northern parts of the country. The temporal and spatial variability of precipitation changes are higher in the statistically downscaled scenarios than in the dynamically downscaled ones. Comparisons of the 4 scenarios show that the spread of the scenarios created by the statistical model is on average larger than that between the RCM scenarios. The relatively large average spread is mainly due to the large differences found in summer. The seasonally averaged difference of the dynamical and statistical scenarios for the ECHAM4-based downscaled scenarios is 12%, and for the HadCM2 downscaled scenarios 21%. The differences in annual precipitation change are smaller, on average 4.5% among the HadCM2-based downscaled scenarios, and 6.9% among the ECHAM4-based downscaling scenarios.

  • 156. Helmert, Juergen
    et al.
    Lange, Martin
    Dong, Jiarui
    De Rosnay, Patricia
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    Churulin, Evgeniy
    Kurzeneva, Ekaterina
    Mueller, Richard
    Trentmann, Joerg
    Souverijns, Niels
    Koch, Roland
    Boehm, Uwe
    Bartik, Martin
    Osuch, Marzena
    Rozinkina, Inna
    Bettems, Jean-Marie
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Marcucci, Francesca
    Milelli, Massimo
    1st Snow Data Assimilation Workshop in the framework of COST HarmoSnow ESSEM 14042018In: Meteorologische Zeitschrift, ISSN 0941-2948, E-ISSN 1610-1227, Vol. 27, no 4, p. 325-333Article in journal (Refereed)
  • 157. Hennemuth, B
    et al.
    Rutgersson, Anna
    SMHI, Research Department, Climate research - Rossby Centre.
    Bumke, K
    Clemens, M
    Omstedt, Anders
    Jacob, D
    Smedman, A S
    Net precipitation over the Baltic Sea for one year using models and data-based methods2003In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 55, no 4, p. 352-367Article in journal (Refereed)
    Abstract [en]

    Precipitation and evaporation over the Baltic Sea are calculated for a one-year period from September 1998 to August 1999 by four different tools, the two atmospheric regional models HIRLAM and REMO, the oceanographic model PROBE-Baltic in combination with the SMHI (1 x 1)degrees database and Interpolated Fields, based essentially on ship measurements. The investigated period is slightly warmer and wetter than the climatological mean. Correlation coefficients of the differently calculated latent heat fluxes vary between 0.81 (HIRLAM and REMO) and 0.56 (SMHI/PROBE-Baltic and Interpolated Fields), while the correlation coefficients between model fluxes and measured fluxes range from 0.61 and 0.78. Deviations of simulated and interpolated monthly precipitation over the Baltic Sea are less than 5 mm in the southern Baltic and up to 20 mm near the Finnish coast for the one-year period. The methods simulate the annual cycle of precipitation and evaporation of the Baltic Proper in a similar manner with a broad maximum of net precipitation in spring and early summer and a minimum in late summer. The annual averages of net precipitation of the Baltic Proper range from 57 mm (REMO) to 262 turn (HIRLAM) and for the Baltic Sea from 96 turn (SMHI/PROBE-Baltic) to 209 rum (HIRLAM). This range is considered to give the uncertainty of present-day determination of the net precipitation over the Baltic Sea.

  • 158. HOFGAARD, A
    et al.
    KULLMAN, L
    Alexandersson, Hans
    SMHI.
    RESPONSE OF OLD-GROWTH MONTANE PICEA-ABIES (L) KARST FOREST TO CLIMATIC VARIABILITY IN NORTHERN SWEDEN1991In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 119, no 4, p. 585-594Article in journal (Refereed)
    Abstract [en]

    Repeat photography and tree ring analyses were used to investigate structural change, 1938-88, of an old growth and high elevation Picea abies (L.) Karst. forest in northern Sweden. The forest, initially moribund, senescent and top-broken, regenerated broken tops and apparently gained in vigour. Up to the 1930s this progressive change was pre-dated by an increase of annual increment growth, which subsequently declined until the 1980s. The tree-ring response concurs with the general course of summer temperature while canopy processes appear to lag behind. The study stresses the importance of phenotypic plasticity for long-term behaviour of marginal spruce forest. It is also evident that canopy development is not a fully predictable ageing process, but to some extent dependent on climatic variability.

  • 159.
    Holmström, Ingemar
    SMHI.
    Optimization of atmospheric models1976Report (Other academic)
    Abstract [en]

    Applying variational methods toa mathematical model of the atmosphere an entirely new type of equations for forecasting atmospheric parameters is derived. The method also defines vertical eigenfunctions to the model. In a simplified case some of the eigenfunctions are compared with empirically obtained data and conclusions are drawn regarding the validity of some of the approximations in the mathematical model.

  • 160.
    Holmström, Ingemar
    et al.
    SMHI.
    Stokes, John
    SMHI.
    Statistical forecasting of sea level changes in the Baltic1978Report (Other academic)
    Abstract [en]

    By expanding sea level data from 6 Swedish observation stations inte empirical orthogonal functions a very simple picture of the response of the Baltic to atmospheric forcing is obtained. It is found that not less than 65.5 per cent of the total variance is due to a general rise or lowering of the whole surface.The time scale corresponds to the time scale of large scale atmospheric disturbances. This inderdependence has been used in order to establish a regression equation between surface pressure fields and sea level variations which is used for prediction. In the statistical treatment extensive use is made of the empirical orthogonal function technique.

  • 161. Hovsenius, Gunnar
    et al.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Konsekvenser för vindkraften i Sverige av klimatförändringar2007Report (Other academic)
  • 162. Iqbal, W.
    et al.
    Syed, F. S.
    Sajjad, H.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Hannachi, A.
    Mean climate and representation of jet streams in the CORDEX South Asia simulations by the regional climate model RCA42017In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 129, no 1-2, p. 1-19Article in journal (Refereed)
  • 163. Jacob, Daniela
    et al.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Ole Bossing
    Christensen, Jens Hesselbjerg
    de Castro, Manuel
    Deque, Michel
    Giorgi, Filippo
    Hagemann, Stefan
    Hirschi, Martin
    Jones, Richard
    Kjellström, Erik
    SMHI, Research Department, Climate research - 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 climate2007In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 81, p. 31-52Article in journal (Refereed)
    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.

  • 164. 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, Research Department, Climate research - Rossby Centre.
    Haensler, Andreas
    Hempelmann, Nils
    Jones, Colin
    SMHI, Research Department, Climate research - 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, Research Department, Climate research - 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 research2014In: Regional Environmental Change, ISSN 1436-3798, E-ISSN 1436-378X, Vol. 14, no 2, p. 563-578Article in journal (Refereed)
    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.

  • 165. Jennings, Eleanor
    et al.
    Allott, Norman
    Pierson, Donald C.
    Schneiderman, Elliot M.
    Lenihan, David
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Taylor, David
    Impacts of climate change on phosphorus loading from a grassland catchment: Implications for future management2009In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 43, no 17, p. 4316-4326Article in journal (Refereed)
    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.

  • 166. Jeong, Jee-Hoon
    et al.
    Walther, Alexander
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Chen, Deliang
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Diurnal cycle of precipitation amount and frequency in Sweden: observation versus model simulation2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, no 4, p. 664-674Article in journal (Refereed)
    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.

  • 167. 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, Research Department, Climate research - Rossby Centre.
    Kotlarski, Sven
    van Meijgaard, Erik
    Teichmann, Claas
    Wild, Martin
    The impact of climate change on photovoltaic power generation in Europe2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, article id 10014Article in journal (Refereed)
    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.

  • 168. Jeworrek, Julia
    et al.
    Wu, Lichuan
    Dieterich, Christian
    SMHI, Research Department, Oceanography.
    Rutgersson, Anna
    SMHI, Research Department, Climate research - Rossby Centre.
    Characteristics of convective snow bands along the Swedish east coast2017In: Earth System Dynamics, ISSN 2190-4979, E-ISSN 2190-4987, Vol. 8, p. 163-175Article in journal (Refereed)
  • 169. 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, Research Department, Climate research - Rossby Centre.
    Zhang, Guang J.
    Zhu, Hongyan
    Vertical structure and physical processes of the Madden-Julian oscillation: Exploring key model physics in climate simulations2015In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 120, no 10, p. 4718-4748Article in journal (Refereed)
    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.

  • 170. Jiao, Yanjun
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Comparison Studies of Cloud- and Convection-Related Processes Simulated by the Canadian Regional Climate Model over the Pacific Ocean2008In: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 136, no 11, p. 4168-4187Article in journal (Refereed)
  • 171. Johansson, Mattias
    et al.
    Galle, Bo
    Zhang, Yan
    Rivera, Claudia
    Chen, Deliang
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    The dual-beam mini-DOAS technique-measurements of volcanic gas emission, plume height and plume speed with a single instrument2009In: Bulletin of Volcanology, ISSN 0258-8900, E-ISSN 1432-0819, Vol. 71, no 7, p. 747-751Article in journal (Refereed)
    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.

  • 172.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Development of physical parameterizations for high resolution Climate models2005In: 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, p. 37-Conference paper (Other academic)
  • 173.
    Jones, Colin
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Willen, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    The Rossby Centre Regional Atmospheric Climate Model part 1: Model climatology and performance for the present climate over Europe2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, no 4-5, p. 199-210Article in journal (Refereed)
    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.

  • 174.
    Jones, Colin
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Willen, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    The Rossby Centre regional atmospheric climate model part II: Application to the Arctic climate2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, no 4-5, p. 211-220Article in journal (Refereed)
    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.

  • 175. Jonsson, A. M.
    et al.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Ensemble analysis of frost damage on vegetation caused by spring backlashes in a warmer Europe2011In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 11, no 2, p. 401-418Article in journal (Refereed)
    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.

  • 176. Jonsson, A. M.
    et al.
    Eklundh, L.
    Hellstrom, M.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Jonsson, P.
    Annual changes in MODIS vegetation indices of Swedish coniferous forests in relation to snow dynamics and tree phenology2010In: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 114, no 11, p. 2719-2730Article in journal (Refereed)
    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.

  • 177. Jonsson, Anna Maria
    et al.
    Appelberg, Gustaf
    Harding, Susanne
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Spatio-temporal impact of climate change on the activity and voltinism of the spruce bark beetle, Ips typographus2009In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 15, no 2, p. 486-499Article in journal (Refereed)
    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.

  • 178. Jonsson, Anna Maria
    et al.
    Harding, Susanne
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Ravn, Hans Peter
    Impact of climate change on the population dynamics of Ips typographus in southern Sweden2007In: Agricultural and Forest Meteorology, ISSN 0168-1923, E-ISSN 1873-2240, Vol. 146, no 1-2, p. 70-81Article in journal (Refereed)
  • 179. Jonsson, P
    et al.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Eliasson, I
    Lindgren, E S
    Suspended particulate matter and its relations to the urban climate in Dar es Salaam, Tanzania2004In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 38, no 25, p. 4175-4181Article in journal (Refereed)
    Abstract [en]

    Relationships between sources and levels of particulate matter and climatic parameters (urban heat island intensity, wind speed, temperature and relative humidity) were investigated in the coastal city of Dar es Salaam, Tanzania's largest city. Measurements were made during the wet and dry seasons of 2001 at an urban and a rural site. Five elements were used to represent different sources: K in fine particles (biomass), Zn in fine particles (industry), Cl in coarse particles (sea spray), Ti in coarse particles (soil) and Pb in fine particles (traffic). The concentrations of these elements varied considerably between the urban and rural site during both the wet and dry season, with the urban site in the dry season having the highest concentrations. Diurnal differences are also apparent, although not as straightforward. In an attempt to explain these differences, correlations between all elements and the climatic parameters were investigated. The results show that the nocturnal urban heat island intensity was positively correlated and wind speed negatively correlated with particulate levels, presumably due to the increased atmospheric stability. (C) 2004 Elsevier Ltd. All rights reserved.

  • 180. 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, Research Department, Climate research - Rossby Centre.
    Matei, Daniela
    Overland, James
    Spengler, Thomas
    Yang, Shuting
    POLAR LOWER-LATITUDE LINKAGES AND THEIR ROLE IN WEATHER AND CLIMATE PREDICTION2015In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 96, no 11, p. ES197-ES200Article in journal (Refereed)
  • 181. Jungclaus, Johann H.
    et al.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Low-frequency variability of the arctic climate: the role of oceanic and atmospheric heat transport variations2010In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 34, no 2-3, p. 265-279Article in journal (Refereed)
  • 182. Jönsson, Anna-Maria
    et al.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Future climate impact on spruce bark beetle life cycle in relation to uncertainties in regional climate model data ensembles2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, p. 158-173Article in journal (Refereed)
  • 183. Kalognomou, Evangelia-Anna
    et al.
    Lennard, Christopher
    Shongwe, Mxolisi
    Pinto, Izidine
    Favre, Alice
    Kent, Michael
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Buechner, Matthias
    A Diagnostic Evaluation of Precipitation in CORDEX Models over Southern Africa2013In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 26, no 23, p. 9477-9506Article, review/survey (Refereed)
    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.

  • 184. Kamarainen, Matti
    et al.
    Hyvarinen, Otto
    Vajda, Andrea
    Nikulin, Grigory
    SMHI, Research Department, Climate research - 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 Models2018In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 123, no 23, p. 13291-13304Article in journal (Refereed)
  • 185.
    Karlsson, Karl-Göran
    et al.
    SMHI, Research Department, Atmospheric remote sensing.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    USE OF A HIGH-RESOLUTION CLOUD CLIMATE DATA SET FOR VALIDATION OF ROSSBY CENTRE CLIMATE SIMULATIONS2004In: 2004 EUMETSAT METEOROLOGICAL SATELLITE CONFERENCE: Ocean and Climate Observations, EUMETSAT , 2004, p. 465-473Conference paper (Other academic)
  • 186.
    Karlsson, Karl-Göran
    et al.
    SMHI, Research Department, Atmospheric remote sensing.
    Willen, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Evaluation of regional cloud climate simulations over Scandinavia using a 10-year NOAA advanced very high resolution radiometer cloud climatology2008In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 113, no D1, article id D01203Article in journal (Refereed)
    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.

  • 187. Kendon, Elizabeth J.
    et al.
    Jones, Richard G.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Murphy, James M.
    Using and Designing GCM-RCM Ensemble Regional Climate Projections2010In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 23, no 24, p. 6485-6503Article in journal (Refereed)
    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.

  • 188.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Daily variability in temperature and precipitation: Recent and future changes over Europe2005In: 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, p. 72-73Conference paper (Other academic)
  • 189.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Evaluating regional climate model simulations of daily maximum and minimum temperatures in the ENSEMBLES project2008In: Abstracts of the contributions of the EGU General Assembly 2008, 2008, Vol. 10, article id EGU2008-A-02262Conference paper (Other academic)
  • 190.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Present-Day and Future Precipitation in the Baltic Region as Simulated in Regional Climate Models2004In: 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)
  • 191.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Recent and future signatures of climate change in Europe2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, no 4-5, p. 193-198Article in journal (Refereed)
    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.

  • 192.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Boberg, Fredrik
    Castro, Manuel
    Christensen, Jens Hesselbjerg
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Sanchez, Enrique
    Daily and monthly temperature and precipitation statistics as performance indicators for regional climate models2010In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 44, no 2-3, p. 135-150Article in journal (Refereed)
    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.

  • 193.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, J.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - 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 models2009Conference paper (Other academic)
  • 194.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, J
    Strandberg, Gustav
    SMHI, Research Department, Climate research - 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 perspective2008In: Abstracts of the contributions of the EGU General Assembly 2008., 2008, Vol. 10, article id EGU2008-A-02249Conference paper (Other academic)
  • 195.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, Jenny
    Naslund, Jens-Ove
    Smith, Ben
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Voelker, Antje H. L.
    Wohlfarth, Barbara
    Simulated climate conditions in Europe during the Marine Isotope Stage 3 stadial2010In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 39, no 2, p. 436-456Article in journal (Refereed)
    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.

  • 196.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Evaluating the method of pattern-scaling in time2006Conference paper (Other academic)
  • 197.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Jacob, Daniela
    Jones, Richard
    Lenderink, Geert
    Schaer, Christoph
    Modelling daily temperature extremes: recent climate and future changes over Europe2007In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 81, p. 249-265Article in journal (Refereed)
    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.

  • 198.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Nilsson, Carin
    Lunds Universitet.
    Persson, Gunn
    SMHI, Professional Services.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Production and use of regional climate model projections – A Swedish perspective on building climate services2016In: Climate Services, ISSN 2405-8807, no 2-3, p. 15-29Article in journal (Refereed)
  • 199.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Atmospheric response to different sea surface temperatures in the Baltic Sea: coupled versus uncoupled regional climate model experiments2005In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 36, no 4-5, p. 397-409Article in journal (Refereed)
    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.

  • 200.
    Kjellström, Erik
    et al.
    SMHI, Research Department, Climate research - 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.2010Conference paper (Other academic)
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v. 2.35.9
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