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  • 1. Ahmadalipour, Ali
    et al.
    Moradkhani, Hamid
    Rana, Arun
    SMHI.
    Accounting for downscaling and model uncertainty in fine-resolution seasonal climate projections over the Columbia River Basin2018In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 50, no 1-2, p. 717-733Article in journal (Refereed)
  • 2. Akinsanola, A. A.
    et al.
    Ajayi, V. O.
    Adejare, A. T.
    Adeyeri, O. E.
    Gbode, I. E.
    Ogunjobi, K. O.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Abolude, A. T.
    Evaluation of rainfall simulations over West Africa in dynamically downscaled CMIP5 global circulation models2018In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 132, no 1-2, p. 437-450Article in journal (Refereed)
  • 3. Akperov, Mirseid
    et al.
    Rinke, Annette
    Mokhov, Igor I.
    Matthes, Heidrun
    Semenov, Vladimir A.
    Adakudlu, Muralidhar
    Cassano, John
    Christensen, Jens H.
    Dembitskaya, Mariya A.
    Dethloff, Klaus
    Fettweis, Xavier
    Glisan, Justin
    Gutjahr, Oliver
    Heinemann, Guenther
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Koldunov, Nikolay V.
    Laprise, Rene
    Mottram, Ruth
    Nikiema, Oumarou
    Scinocca, John F.
    Sein, Dmitry
    Sobolowski, Stefan
    Winger, Katja
    Zhang, Wenxin
    Cyclone Activity in the Arctic From an Ensemble of Regional Climate Models (Arctic CORDEX)2018In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 123, no 5, p. 2537-2554Article in journal (Refereed)
  • 4.
    Alexandersson, Hans
    et al.
    SMHI.
    Moberg, A
    Homogenization of Swedish temperature data .1. Homogeneity test for linear trends1997In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 17, no 1, p. 25-34Article in journal (Refereed)
    Abstract [en]

    A new test for the detection of linear trends of arbitrary length in normally distributed time series is developed. With this test it is possible to detect and estimate gradual changes of the mean value in a candidate series compared with a homogeneous reference series. The test is intended for studies of artificial relative trends in climatological time series, e.g. an increasing urban heat island effect. The basic structure of the new test is similar to that of a widely used test for abrupt changes, the standard normal homogeneity test. The test for abrupt changes is found to remain unaltered after an important generalization.

  • 5.
    Alexandersson, Hans
    et al.
    SMHI.
    Tuomenvirta, H
    Schmith, T
    Iden, K
    Trends of storms in NW Europe derived from an updated pressure data set2000In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 14, no 1, p. 71-73Article in journal (Refereed)
    Abstract [en]

    Within the WASA project (von Storch et al. 1998; Bull Am Meterol Soc 79(5):741-760) an extensive data set containing station pressure values was used to calculate geostrophic winds (Alexandersson et al. 1998; Global Atmos Ocean Syst 6:97-120). Geostrophic winds were analysed in terms of percentiles to give a measure of long-term variations in synoptic-scale storminess. In this paper an update to 1998 is presented. In the Scandinavia, Finland and Baltic Sea area the most recent years, especially the cold and calm year 1996, seem to have brought an end to the stormy period centred on 1990. In the more westerly British Isles, North Sea and Norwegian Sea area, storminess is still at high levels compared with the less intense period between 1930 and 1980. The long-term increasing trend in NW Europe storminess that started in the 1960s seems to have been broken.

  • 6. Alfieri, Lorenzo
    et al.
    Bisselink, Berny
    Dottori, Francesco
    Naumann, Gustavo
    de Roo, Ad
    Salamon, Peter
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Feyen, Luc
    Global projections of river flood risk in a warmer world2017In: Earth's Future, ISSN 1384-5160, E-ISSN 2328-4277, Vol. 5, no 2, p. 171-182Article in journal (Refereed)
  • 7. Anderson, C J
    et al.
    Arritt, R W
    Takle, E S
    Pan, Z T
    Gutowski, W J
    Otieno, F O
    da Silva, R
    Caya, D
    Christensen, J H
    Luthi, D
    Gaertner, M A
    Gallardo, C
    Giorgi, F
    Hong, S Y
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Juang, H M H
    Katzfey, J J
    Lapenta, W M
    Laprise, R
    Larson, J W
    Liston, G E
    McGregor, J L
    Pielke, R A
    Roads, J O
    Taylor, J A
    Hydrological processes in regional climate model simulations of the central United States flood of June-July 19932003In: Journal of Hydrometeorology, ISSN 1525-755X, E-ISSN 1525-7541, Vol. 4, no 3, p. 584-598Article in journal (Refereed)
    Abstract [en]

    Thirteen regional climate model(RCM) simulations of June - July 1993 were compared with each other and observations. Water vapor conservation and precipitation characteristics in each RCM were examined for a 108 x 10degrees subregion of the upper Mississippi River basin, containing the region of maximum 60-day accumulated precipitation in all RCMs and station reports. All RCMs produced positive precipitation minus evapotranspiration ( P - E > 0), though most RCMs produced P - E below the observed range. RCM recycling ratios were within the range estimated from observations. No evidence of common errors of E was found. In contrast, common dry bias of P was found in the simulations. Daily cycles of terms in the water vapor conservation equation were qualitatively similar in most RCMs. Nocturnal maximums of P and C ( convergence) occurred in 9 of 13 RCMs, consistent with observations. Three of the four driest simulations failed to couple P and C overnight, producing afternoon maximum P. Further, dry simulations tended to produce a larger fraction of their 60-day accumulated precipitation from low 3-h totals. In station reports, accumulation from high ( low) 3-h totals had a nocturnal ( early morning) maximum. This time lag occurred, in part, because many mesoscale convective systems had reached peak intensity overnight and had declined in intensity by early morning. None of the RCMs contained such a time lag. It is recommended that short-period experiments be performed to examine the ability of RCMs to simulate mesoscale convective systems prior to generating long-period simulations for hydroclimatology.

  • 8.
    Andersson, Lotta
    et al.
    SMHI, Research Department, Hydrology.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Assessment of climate change impact on water resources in the Pungwe river basin2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, no 1, p. 138-157Article in journal (Refereed)
  • 9. Arritt, Raymond W.
    et al.
    Rummukainen, Markku
    SMHI, Core Services.
    CHALLENGES IN REGIONAL-SCALE CLIMATE MODELING2011In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 92, no 3, p. 365-368Article in journal (Other academic)
  • 10. Astrom, Christofer
    et al.
    Orru, Hans
    Rocklov, Joacim
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Ebi, Kristie L.
    Forsberg, Bertil
    Heat-related respiratory hospital admissions in Europe in a changing climate: a health impact assessment2013In: BMJ Open, ISSN 2044-6055, E-ISSN 2044-6055, Vol. 3, no 1, article id e001842Article in journal (Refereed)
    Abstract [en]

    Objectives: Respiratory diseases are ranked second in Europe in terms of mortality, prevalence and costs. Studies have shown that extreme heat has a large impact on mortality and morbidity, with a large relative increase for respiratory diseases. Expected increases in mean temperature and the number of extreme heat events over the coming decades due to climate change raise questions about the possible health impacts. We assess the number of heat-related respiratory hospital admissions in a future with a different climate. Design: A Europe-wide health impact assessment. Setting: An assessment for each of the EU27 countries. Methods: Heat-related hospital admissions under a changing climate are projected using multicity epidemiological exposure-response relationships applied to gridded population data and country-specific baseline respiratory hospital admission rates. Times-series of temperatures are simulated with a regional climate model based on four global climate models, under two greenhouse gas emission scenarios. Results: Between a reference period (1981-2010) and a future period (2021-2050), the total number of respiratory hospital admissions attributed to heat is projected to be larger in southern Europe, with three times more heat attributed respiratory hospital admissions in the future period. The smallest change was estimated in Eastern Europe with about a twofold increase. For all of Europe, the number of heat-related respiratory hospital admissions is projected to be 26 000 annually in the future period compared with 11 000 in the reference period. Conclusions: The results suggest that the projected effects of climate change on temperature and the number of extreme heat events could substantially influence respiratory morbidity across Europe.

  • 11. Belda, Michal
    et al.
    Skalak, Petr
    Farda, Ales
    Halenka, Tomas
    Deque, Michel
    Csima, Gabriella
    Bartholy, Judit
    Torma, Csaba
    Boroneant, Constanta
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Spiridonov, Valery
    CECILIA Regional Climate Simulations for Future Climate: Analysis of Climate Change Signal2015In: Advances in Meteorology, ISSN 1687-9309, E-ISSN 1687-9317, article id 354727Article in journal (Refereed)
    Abstract [en]

    Regional climate models (RCMs) are important tools used for downscaling climate simulations from global scale models. In project CECILIA, two RCMs were used to provide climate change information for regions of Central and Eastern Europe. Models RegCM and ALADIN-Climate were employed in downscaling global simulations from ECHAM5 and ARPEGE-CLIMAT under IPCC A1B emission scenario in periods 2021-2050 and 2071-2100. Climate change signal present in these simulations is consistent with respective driving data, showing similar large-scale features: warming between 0 and 3 degrees C in the first period and 2 and 5 degrees C in the second period with the least warming in northwestern part of the domain increasing in the southeastern direction and small precipitation changes within range of +1 to -1 mm/day. Regional features are amplified by the RCMs, more so in case of the ALADIN family of models.

  • 12. Beldring, S.
    et al.
    Andréasson, J.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Graham, Phil
    SMHI, Professional Services.
    Jónsdóttir, J. F
    Rogozova, S.
    Rosberg, Jörgen
    SMHI, Research Department, Hydrology.
    Suomalainen, M.
    Tonning, T.
    Vehviläinen, B.
    Veijalainen, N.
    Mapping water resources in the Nordic region under a changing climate.2006Report (Other academic)
  • 13. Bellucci, A.
    et al.
    Haarsma, R.
    Bellouin, N.
    Booth, B.
    Cagnazzo, C.
    van den Hurk, B.
    Keenlyside, N.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Massonnet, F.
    Materia, S.
    Weiss, M.
    Advancements in decadal climate predictability: The role of nonoceanic drivers2015In: Reviews of geophysics, ISSN 8755-1209, E-ISSN 1944-9208, Vol. 53, no 2, p. 165-202Article in journal (Refereed)
    Abstract [en]

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

  • 14. Bellucci, A.
    et al.
    Haarsma, R.
    Gualdi, S.
    Athanasiadis, P. J.
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Cassou, C.
    Fernandez, E.
    Germe, A.
    Jungclaus, J.
    Kroeger, J.
    Matei, D.
    Mueller, W.
    Pohlmann, H.
    Salas y Melia, D.
    Sanchez, E.
    Smith, D.
    Terray, L.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Yang, S.
    An assessment of a multi-model ensemble of decadal climate predictions2015In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 44, no 9-10, p. 2787-2806Article in journal (Refereed)
    Abstract [en]

    A multi-model ensemble of decadal prediction experiments, performed in the framework of the EU-funded COMBINE (Comprehensive Modelling of the Earth System for Better Climate Prediction and Projection) Project following the 5th Coupled Model Intercomparison Project protocol is examined. The ensemble combines a variety of dynamical models, initialization and perturbation strategies, as well as data assimilation products employed to constrain the initial state of the system. Taking advantage of the multi-model approach, several aspects of decadal climate predictions are assessed, including predictive skill, impact of the initialization strategy and the level of uncertainty characterizing the predicted fluctuations of key climate variables. The present analysis adds to the growing evidence that the current generation of climate models adequately initialized have significant skill in predicting years ahead not only the anthropogenic warming but also part of the internal variability of the climate system. An important finding is that the multi-model ensemble mean does generally outperform the individual forecasts, a well-documented result for seasonal forecasting, supporting the need to extend the multi-model framework to real-time decadal predictions in order to maximize the predictive capabilities of currently available decadal forecast systems. The multi-model perspective did also allow a more robust assessment of the impact of the initialization strategy on the quality of decadal predictions, providing hints of an improved forecast skill under full-value (with respect to anomaly) initialization in the near-term range, over the Indo-Pacific equatorial region. Finally, the consistency across the different model predictions was assessed. Specifically, different systems reveal a general agreement in predicting the near-term evolution of surface temperatures, displaying positive correlations between different decadal hindcasts over most of the global domain.

  • 15.
    Bengtsson,, Lennart
    et al.
    SMHI.
    Gustafsson, Nils
    SMHI, Research Department, Meteorology.
    Döös, Bo
    SMHI.
    Söderman, Daniel
    Helsinki University in Finland.
    Moen, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Thompson, Thomas
    SMHI.
    Jakobsson, Paul
    SMHI.
    Bleckert, Gunnar
    SMHI.
    Henriksson, Ann-Beate
    SMHI.
    Lindgren, Bo
    SMHI.
    Kållberg, Per
    SMHI, Research Department, Meteorology.
    The Meteorological Auto Code (MAC) and Numerical Weather Prediction (NWP) at SMHI2016Report (Other academic)
    Abstract [en]

    Sweden was a pioneering country in the development of NumericalWeather Prediction (NWP). The worlds first operational numerical forecast was produced already in 1954 by the International Meteorological Institute in Stockholm. SMHI started a bit later, but in 1961 a long term program for development of NWP was initiated. The activities grew gradually during the 1960’s and resulted in a core component for the SMHI forecast services. An early challenge was to overcome the limited computational resources with slow computational speed, small memory size and primitive software support. It was necessary to compensate for these limitations with dedicated work and creativity. A core component in this work was the software system MAC (Meteorological Auto Code) that was developed by the NWP group at SMHI. The MAC system is described in detail in this report and it included all computational software needed for the weather service, for example numerical models, objective analysis techniques, automatic data extraction, quality control of observations as well as forecast products in graphical or digital form.

    We hope that this report will provide the younger generation with some insight into the conditions for development of NWP during the 1960’s.

  • 16.
    Berg, Peter
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Impacts of using spectral nudging on regional climate model RCA4 simulations of the Arctic2013In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 6, no 3, p. 849-859Article in journal (Refereed)
    Abstract [en]

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

  • 17.
    Berg, Peter
    et al.
    SMHI, Research Department, Hydrology.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    On the effects of constraining atmospheric circulation in a coupled atmosphere-ocean Arctic regional climate model2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 11-12, p. 3499-3515Article in journal (Refereed)
  • 18.
    Berg, Peter
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Feldmann, H.
    Panitz, H. -J
    Bias correction of high resolution regional climate model data2012In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 448, p. 80-92Article in journal (Refereed)
    Abstract [en]

    Bias correction of varying complexity - from simple scaling and additive corrections to more advanced histogram equalisation (HE) corrections - is applied to high resolution (7 km) regional climate model (RCM) simulations. The aim of the study is to compare different methods that are easily implemented and applied to the data, and to assess the applicability and impact of the bias correction depending on the type of bias. The model bias is determined by comparison to a new gridded high resolution (1 km) data set of temperature and precipitation, which is also used as reference for the corrections. The performance of the different methods depends on the type of bias of the model, and on the investigated statistic. Whereas simpler methods correct the first moment of the distributions, they can have adverse effects on higher moments. The HE method corrects also higher moments, but approximations of the transfer function are necessary when applying the method to other data than the calibration data. Here, an empirical transfer function with linear fits to the tails is compared to a version where the complete function is approximated by a linear fit. The latter is thus limited to corrections of the first and second moments of the distribution. While making the transfer function more generally applicable, these approximations also limit the performance of the HE method. For the current model biases, the linear approximation is found suitable for precipitation, but for temperature it is not able to correct the whole distribution. The lower performance of the linear correction is most pronounced in summer, and is likely due to a difference in skewness between the model and observational data. Further limitations of the HE method are due to the need for long time series in order to have robust distributions for calculating the transfer function. Theoretical approximations of the required length of the calibration period were performed by using different sampling sizes drawn from a known distribution. The excerise show that about 30 year long time series are needed to have reasonable accuracy for the estimation of variance, when also corrections of the annual cycle is required. (C) 2012 Elsevier B.V. All rights reserved.

  • 19.
    Berg, Peter
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Moseley, Christopher
    Haerter, Jan O.
    Strong increase in convective precipitation in response to higher temperatures2013In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 6, no 3, p. 181-185Article in journal (Refereed)
    Abstract [en]

    Precipitation changes can affect society more directly than variations in most other meteorological observables(1-3), but precipitation is difficult to characterize because of fluctuations on nearly all temporal and spatial scales. In addition, the intensity of extreme precipitation rises markedly at higher temperature(4-9), faster than the rate of increase in the atmosphere's water-holding capacity(1,4), termed the Clausius-Clapeyron rate. Invigoration of convective precipitation (such as thunderstorms) has been favoured over a rise in strati-form precipitation (such as large-scale frontal precipitation) as a cause for this increase(4,10), but the relative contributions of these two types of precipitation have been difficult to disentangle. Here we combine large data sets from radar measurements and rain gauges over Germany with corresponding synoptic observations and temperature records, and separate convective and stratiform precipitation events by cloud observations. We find that for stratiform precipitation, extremes increase with temperature at approximately the Clausius-Clapeyron rate, without characteristic scales. In contrast, convective precipitation exhibits characteristic spatial and temporal scales, and its intensity in response to warming exceeds the Clausius-Clapeyron rate. We conclude that convective precipitation responds much more sensitively to temperature increases than stratiform precipitation, and increasingly dominates events of extreme precipitation.

  • 20.
    Berg, Peter
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Wagner, Sven
    Kunstmann, Harald
    Schaedler, Gerd
    High resolution regional climate model simulations for Germany: part I-validation2013In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 40, no 1-2, p. 401-414Article in journal (Refereed)
    Abstract [en]

    A five-member ensemble of regional climate model (RCM) simulations for Europe, with a high resolution nest over Germany, is analysed in a two-part paper: Part I (the current paper) presents the performance of the models for the control period, and Part II presents results for near future climate changes. Two different RCMs, CLM and WRF, were used to dynamically downscale simulations with the ECHAM5 and CCCma3 global climate models (GCMs), as well as the ERA40-reanalysis for validation purposes. Three realisations of ECHAM5 and one with CCCma3 were downscaled with CLM, and additionally one realisation of ECHAM5 with WRF. An approach of double nesting was used, first to an approximately 50 km resolution for entire Europe and then to a domain of approximately 7 km covering Germany and its near surroundings. Comparisons of the fine nest simulations are made to earlier high resolution simulations for the region with the RCM REMO for two ECHAM5 realisations. Biases from the GCMs are generally carried over to the RCMs, which can then reduce or worsen the biases. The bias of the coarse nest is carried over to the fine nest but does not change in amplitude, i.e. the fine nest does not add additional mean bias to the simulations. The spatial pattern of the wet bias over central Europe is similar for all CLM simulations, and leads to a stronger bias in the fine nest simulations compared to that of WRF and REMO. The wet bias in the CLM model is found to be due to a too frequent drizzle, but for higher intensities the distributions are well simulated with both CLM and WRF at the 50 and 7 km resolutions. Also the spatial distributions are close to high resolution gridded observations. The REMO model has low biases in the domain averages over Germany and no drizzle problem, but has a shift in the mean precipitation patterns and a strong overestimation of higher intensities. The GCMs perform well in simulating the intensity distribution of precipitation at their own resolution, but the RCMs add value to the distributions when compared to observations at the fine nest resolution.

  • 21.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Carlsson, Bengt
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Pettersson, Anna
    SMHI, Research Department, Hydrology.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Climate change impacts on runoff in Sweden - assessments by global climate models, dynamical downscaling and hydrological modelling2001In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 16, no 2, p. 101-112Article in journal (Refereed)
    Abstract [en]

    The Swedish regional climate modelling programme, SWECLIM, started in 1997 with the main goal being to produce regional climate change scenarios over the Nordic area on a time scale of 50 to 100 yr. An additional goal is to produce water resources scenarios with a focus on hydropower production, dam safety, water supply and environmental aspects of water resources. The scenarios are produced by a combination of global climate models (GCMs), regional climate models and hydrological runoff models. The GCM simulations used thus far are 10 yr time slices from 2 different GCMs, UKMO HadCM2 from the Hadley Centre and the ECHAM4/OPYC3 of the Max Planck Institute for Meteorology. The regional climate model is a modified version of the international HIRLAM forecast model and the hydrological model is the HBV model developed at the Swedish Meteorological and Hydrological Institute. Scenarios of river runoff have been simulated for 6 selected basins covering the major climate regions in Sweden. Changes in runoff totals, runoff regimes and extreme values have been analysed with a focus on the uncertainties introduced by the choice of GCM and routines for estimation of evapotranspiration in the hydrological model. It is further shown how these choices affect the statistical return periods of future extremes in a design situation.

  • 22. Berlin, Mats
    et al.
    Persson, Torgny
    Jansson, Gunnar
    Haapanen, Matti
    Ruotsalainen, Seppo
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Gull, Bengt Andersson
    Scots pine transfer effect models for growth and survival in Sweden and Finland2016In: Silva Fennica, ISSN 0037-5330, E-ISSN 2242-4075, Vol. 50, no 3, article id 1562Article in journal (Refereed)
    Abstract [en]

    In this study, we developed models of transfer effects for growth and survival of Scots pine (Pinus sylvestris L.) in Sweden and Finland using a general linear mixed-model approach. For model development, we used 378 provenance and progeny trials with a total of 276 unimproved genetic entries (provenances and stand seed check-lots) distributed over a wide variety of climatic conditions in both countries. In addition, we used 119 progeny trials with 3921 selected genetic entries (open-and control pollinated plus-tree families) for testing model performance. As explanatory variables, both climatic indices derived from high-resolution gridded climate datasets and geographical variables were used. For transfer, latitude (photoperiod) and, for describing the site, temperature sum were found to be main drivers for both survival and growth. In addition, interaction terms (between transfer in latitude and site altitude for survival, and transfer in latitude and temperature sum for growth) entail changed reaction patterns of the models depending on climatic conditions of the growing site. The new models behave in a way that corresponds well to previous studies and recommendations for both countries. The model performance was tested using selected plus-trees from open and control pollinated progeny tests. Results imply that the models are valid for both countries and perform well also for genetically improved material. These models are the first step in developing common deployment recommendations for genetically improved forest regeneration material in both Sweden and Finland.

  • 23. Betts, Richard A.
    et al.
    Alfieri, Lorenzo
    Bradshaw, Catherine
    Caesar, John
    Feyen, Luc
    Friedlingstein, Pierre
    Gohar, Laila
    Koutroulis, Aristeidis
    Lewis, Kirsty
    Morfopoulos, Catherine
    Papadimitriou, Lamprini
    Richardson, Katy J.
    Tsanis, Ioannis
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Changes in climate extremes, fresh water availability and vulnerability to food insecurity projected at 1.5 degrees C and 2 degrees C global warming with a higher-resolution global climate model2018In: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, E-ISSN 1471-2962, Vol. 376, no 2119, article id 20160452Article in journal (Refereed)
  • 24. Bjorkman, Christer
    et al.
    Kindvall, Oskar
    Hoglund, Solveig
    Lilja, Anna
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Eklund, Karin
    High Temperature Triggers Latent Variation among Individuals: Oviposition Rate and Probability for Outbreaks2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 1, article id e16590Article in journal (Refereed)
    Abstract [en]

    Background: It is anticipated that extreme population events, such as extinctions and outbreaks, will become more frequent as a consequence of climate change. To evaluate the increased probability of such events, it is crucial to understand the mechanisms involved. Variation between individuals in their response to climatic factors is an important consideration, especially if microevolution is expected to change the composition of populations. Methodology/Principal Findings: Here we present data of a willow leaf beetle species, showing high variation among individuals in oviposition rate at a high temperature (20 degrees C). It is particularly noteworthy that not all individuals responded to changes in temperature; individuals laying few eggs at 20 degrees C continued to do so when transferred to 12 degrees C, whereas individuals that laid many eggs at 20 degrees C reduced their oviposition and laid the same number of eggs as the others when transferred to 12 degrees C. When transferred back to 20 degrees C most individuals reverted to their original oviposition rate. Thus, high variation among individuals was only observed at the higher temperature. Using a simple population model and based on regional climate change scenarios we show that the probability of outbreaks increases if there is a realistic increase in the number of warm summers. The probability of outbreaks also increased with increasing heritability of the ability to respond to increased temperature. Conclusions/Significance: If climate becomes warmer and there is latent variation among individuals in their temperature response, the probability for outbreaks may increase. However, the likelihood for microevolution to play a role may be low. This conclusion is based on the fact that it has been difficult to show that microevolution affect the probability for extinctions. Our results highlight the urge for cautiousness when predicting the future concerning probabilities for extreme population events.

  • 25. Blenckner, T
    et al.
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    A Swedish case study of contemporary and possible future consequences of climate change on lake function2002In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 64, no 2, p. 171-184Article in journal (Refereed)
    Abstract [en]

    A physical lake model was employed to obtain a basis of discussing the impact of climate variability and climate change on the ecology of Lake Erken, Sweden. The validity of this approach was tested by running the PROBE-lake model for a 30-year period (STD) with observed meteorological data. The lake is adequately modelled, as seen in the comparison with actual lake observations. The validated lake model was then forced with meteorological data obtained from a regional climate model (RCM) with a horizontal resolution of 44 km for present (CLTR) and 2 x CO(2) (SCEN) climate conditions. The CUR lake simulation compares reasonably with the STD. Applying the SCEN simulation leads to a climate change scenario for the lake. The physical changes include elevated temperatures, shorter periods of ice cover combined with two of ten years being totally ice-free, and changes in the mixing regime. The ecological consequences of the physical simulation results are derived from the historical dataset of Lake Erken. Consequences of a warmer climate could imply increased nutrient cycling and lake productivity. The results suggest that an application of RCMs with a suitable resolution for lakes in combination with physical lake models allows projection of the responses of lakes to a future climate.

  • 26. Boone, Aaron
    et al.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Gollvik, Stefan
    SMHI, Research Department, Meteorology.
    Napoly, Adrien
    Jarlan, Lionel
    Brun, Eric
    Decharme, Bertrand
    The interactions between soil-biosphere-atmosphere land surface model with a multi-energy balance (ISBA-MEB) option in SURFEXv8-Part 1: Model description2017In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 10, no 2, p. 843-872Article in journal (Refereed)
  • 27. Boucher, Etienne
    et al.
    Nicault, Antoine
    Arseneault, Dominique
    Begin, Yves
    Karami, Mehdi Pasha
    SMHI, Research Department, Climate research - Rossby Centre.
    Decadal Variations in Eastern Canada's Taiga Wood Biomass Production Forced by Ocean-Atmosphere Interactions2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 2457Article in journal (Refereed)
  • 28. Bowling, L C
    et al.
    Lettenmaier, D P
    Nijssen, B
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Clark, D B
    El Maayar, M
    Essery, R
    Goers, S
    Gusev, Y M
    Habets, F
    van den Hurk, B
    Jin, J M
    Kahan, D
    Lohmann, D
    Ma, X Y
    Mahanama, S
    Mocko, D
    Nasonova, O
    Niu, G Y
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Shmakin, A B
    Takata, K
    Verseghy, D
    Viterbo, P
    Xia, Y L
    Xue, Y K
    Yang, Z L
    Simulation of high-latitude hydrological processes in the Torne-Kalix basin: PILPS phase 2(e) - 1: Experiment description and summary intercomparisons2003In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 38, no 1-2, p. 1-30Article in journal (Refereed)
    Abstract [en]

    Twenty-one land-surface schemes (LSSs) participated in the Project for Intercomparison of Land-surface Parameterizations (PILPS) Phase 2(e) experiment, which used data from the Tome-Kalix Rivers in northern Scandinavia. Atmospheric forcing data (precipitation, air temperature, specific humidity, wind speed, downward shortwave and longwave radiation) for a 20-year period (1979-1998) were provided to the 21 participating modeling groups for 218 1/4degrees grid cells that represented the study domain. The first decade (1979-1988) of the period was used for model spin-up. The quality of meteorologic forcing variables is of particular concern in high-latitude experiments and the quality of the gridded dataset was assessed to the extent possible. The lack of sub-daily precipitation, underestimation of true precipitation and the necessity to estimate incoming solar radiation were the primary data concerns for this study. The results from two of the three types of runs are analyzed in this, the first of a three-part paper: (1) calibration-validation runs-calibration of model parameters using observed streamflow was allowed for two small catchments (570 and 1300 km(2)), and parameters were then transferred to two other catchments of roughly similar size (2600 and 1500 km(2)) to assess the ability of models to represent ungauged areas elsewhere; and 2) reruns-using revised forcing data (to resolve problems with apparent underestimation of solar radiation of approximately 36%, and certain other problems with surface wind in the original forcing data). Model results for the period 1989-1998 are used to evaluate the performance of the participating land-surface schemes in a context that allows exploration of their ability to capture key processes spatially. In general, the experiment demonstrated that many of the LSSs are able to capture the limitations imposed on annual latent heat by the small net radiation available in this high-latitude environment. Simulated annual average net radiation varied between 16 and 40 W/m(2) for the 21 models, and latent heat varied between 18 and 36 W/m(2). Among-model differences in winter latent heat due to the treatment of aerodynamic resistance appear to be at least as important as those attributable to the treatment of canopy interception. In many models, the small annual net radiation forced negative sensible heat on average, which varied among the models between - 11 and 9 W/m(2). Even though the largest evaporation rates occur in the summer (June, July and August), model-predicted snow sublimation in winter has proportionately more influence on differences in annual runoff volume among the models. A calibration experiment for four small sub-catchments of the Torne-Kalix basin showed that model parameters that are typically adjusted during calibration, those that control storage of moisture in the soil column or on the land surface via ponding, influence the seasonal distribution of runoff, but have relatively little impact on annual runoff ratios. Similarly, there was no relationship between annual runoff ratios and the proportion of surface and subsurface discharge for the basin as a whole. (C) 2003 Elsevier Science B.V. All rights reserved.

  • 29. Brandefelt, J.
    et al.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Naslund, J. -O
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Voelker, A. H. L.
    Wohlfarth, B.
    A coupled climate model simulation of Marine Isotope Stage 3 stadial climate2011In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 7, no 2, p. 649-670Article in journal (Refereed)
  • 30. Brandefelt, Jenny
    et al.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Näslund, Jens-Ove
    Strandberg, Gustav
    Voelker, Antje
    Wohlfarth, Barbara
    The importance of equilibration in glacial climate simulations2010In: Geophysical Research Abstracts, 2010, Vol. 12, article id EGU2010-10736Conference paper (Refereed)
  • 31.
    Bringfelt, Björn
    SMHI, Research Department, Climate research - Rossby Centre.
    PARTICLE CONCENTRATION MODEL IN A SMALL TOWN STREET BASED ON RECEPTOR STUDIES1987In: Journal of Aerosol Science, ISSN 0021-8502, E-ISSN 1879-1964, Vol. 18, no 6, p. 841-844Article in journal (Refereed)
  • 32.
    Bringfelt, Björn
    et al.
    SMHI.
    Backström, Hans
    SMHI, Professional Services.
    Kindell, Sven
    SMHI, Professional Services.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Calculations of PM-10 concentrations in Swedish cities - Modelling of inhalable particles1997Report (Other academic)
  • 33.
    Bringfelt, Björn
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    LINDROTH, A
    SYNOPTIC EVAPOTRANSPIRATION MODEL APPLIED TO 2 NORTHERN FORESTS OF DIFFERENT DENSITY1987In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 95, no 3-4, p. 185-201Article in journal (Refereed)
  • 34. Brodeau, Laurent
    et al.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Extinction of the northern oceanic deep convection in an ensemble of climate model simulations of the 20th and 21st centuries2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 9-10, p. 2863-2882Article in journal (Refereed)
  • 35.
    Bärring, Lars
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Berlin, Mats
    Andersson Gull, Bengt
    Tailored climate indices for climate-proofing operational forestry applications in Sweden and Finland2017In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 37, no 1, p. 123-142Article in journal (Refereed)
  • 36.
    Bärring, Lars
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Jens
    Déqué, Michel
    Giorgi, Filippo
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Richard
    Laprise, René
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    von Storch, Hans
    Synthesis of Workshop2005In: Extended abstracts of a WMO/WCRP-sponsored Regional-Scale Climate Modelling Workshop : high-resolution climate modelling : assessment, added value and applications, Lund, Sweden, 29 March-2 April 2004 / [ed] Bärring, Lars; René, Laprise, Department of Physical Geography & Ecosystem Analysis, Lund University, Sweden , 2005, p. 18-25Conference paper (Other academic)
  • 37.
    Bärring, Lars
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Fortuniak, Krzysztof
    Multi-indices analysis of southern Scandinavian storminess 1780-2005 and links to interdecadal variations in the NW Europe-North Sea region2009In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 29, no 3, p. 373-384Article in journal (Refereed)
    Abstract [en]

    Extra-tropical cyclone frequency and intensity are Currently under intense scrutiny because of the destruction recent windstorms have brought to Europe, and because they are a major meridional heat transport mechanism that may respond to differential latitudinal warming trends. Several studies using reanalysis data covering the second half of the 20th century Suggest increasing storm intensity in the northeastern Atlantic and European sector. Fewer analyses cover a longer time period but show different trends or point towards the dominance of interdecadal variability instead of ally clear trends. Hence, it is relevant to analyse cyclone variability over as long a period as possible. In this Study, we analyse interdecadal variability in cyclone activity over northwestern Europe back to AD 1780 by combining information from eight storminess indices applied in all Eulerian framework. These indices, including four new approaches towards gauging cyclone activity, use the series of thrice-daily sea level pressure observations at Lund and Stockholm. We find pronounced interdecadal variability in cyclonic activity but no significant overall consistent long-term trend. The major interdecadal-scale variability common to all indices is in good agreement with geostrophic wind reconstructions for NE Atlantic and NW Europe, and with variations in the North Atlantic oscillation (NAO). Our results show that the reanalysis studies cover a time period chiefly coinciding with a marked, but not exceptional in our 225-year perspective, positive variation in the regional cyclone activity that has more recently reversed. Because of the interdecadal variations, a near-centennial time perspective is needed when analysing variations in extra-tropical cyclone activity and the associated weather conditions over northwestern Europe. Copyright (C) 2009 Royal Meteorological Society

  • 38.
    Bärring, Lars
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Holt, Tom
    Linderson, Maj-Lena
    Radziejewski, Madej
    Moriondo, Marco
    Palutikof, Jean P.
    Defining dry/wet spells for point observations, observed area averages, and regional climate model gridboxes in Europe2006In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 31, no 1, p. 35-49Article in journal (Refereed)
    Abstract [en]

    A new method for optimising threshold values of dry/wet spells is evaluated. A set of indices is used to find the best threshold giving good correspondence between the frequency of dry/wet spells in Hadley Centre regional model (HadRM3) output, reference observations with predetermined thresholds, and area-averaged observations. The analyses focus on selected model gridboxes in 3 different European climate regimes (Sweden, UK, Italy), where station data are available from several locations. In addition, a pan-European analysis using the European Climate Assessment (ECA) dataset is carried out. Generally, there is good agreement between point observations and the corresponding area average using the common thresholds of 0.1 or 1.0 mm with observational data. Applying the optimal thresholds on the model output is important, as it typically results in substantially better agreement between the simulated and observed series of dry/wet days. The fitted optimal pan-European dry/wet threshold is (1) 0.47 or 0.15 mm, depending on model version, for the observed point data threshold of 0.1 mm, and (2) 1.2 or 0.56 mm, depending on model version, for the threshold of 1.0 mm.

  • 39.
    Bärring, Lars
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Jonsson, P
    Achberger, C
    Ekstrom, M
    Alexandersson, Hans
    SMHI.
    The Lund instrumental record of meteorological observations: Reconstruction of monthly sea-level pressure 1780-19971999In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 19, no 13, p. 1427-1443Article in journal (Refereed)
    Abstract [en]

    The reconstructed surface air pressure series from Lund, southern Sweden, covers the period 1780-1997 and comprises mon than 234000 valid observations (three observations per day), i.e. > 98% of all possible observation occasions. For the Early Instrumental Period (EIP; 1780-1860) data were digitised from the original records. For most of the Modern Instrumental Period (MIP; 1861-) a series was compiled from various databases containing instrument corrected data. During EIP, the series of raw monthly means show several substantial inhomogeneities. With the aid of a detailed reconstruction of the station history, it was possible to remove almost all inhomogeneities during EIP by applying the correct instrument corrections (for barometer temperature, to standard gravity and to mean sea-level pressure) to the series of original observations. In particular, corrections for the temperature and altitude of the barometer eliminated several inhomogeneities. A prerequisite for applying these corrections is the availability of high-resolution data (actual raw observations or daily averages). Further homogenisation was attained by intercomparison of the monthly mean pressure with acknowledged homogeneous series (mainly the UKMO monthly grid, station records from Copenhagen and Edinburgh). Statistical tests of homogeneity showed that no substantial inhomogeneities remain in the final version. The modern part of the final monthly pressure series largely follows that of the southern Baltic Sea region. Furthermore, it shows relatively high pressure during spring (MAM) in the period 1780-1820, which was paralleled by severe wind erosion in southern Scandinavia during this time. Relatively high pressure throughout the year is also notable during a period of precipitation deficit in 1970s. Copyright (C) 1999 Royal Meteorological Society.

  • 40.
    Bärring, Lars
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Persson, Gunn
    SMHI, Professional Services.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Evaluation of climate extremes in transient runs with the new Rossby Centre regional atmospheric model.2006In: Abstracts of the contributions of the EGU General Assembly 2006, EGU06-A-10110, 2006Conference paper (Other academic)
  • 41.
    Bärring, Lars
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Does the projected pathway to global warming targets matter?2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 2, article id 024029Article in journal (Refereed)
  • 42.
    Bärring, Lars
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    von Storch, H
    Scandinavian storminess since about 18002004In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 31, no 20, article id L20202Article in journal (Refereed)
    Abstract [en]

    We study the history of storminess in Northern Europe, as derived from local pressure observations in Lund since 1780 and Stockholm since 1820 ( Sweden). At both stations barometer readings were made three times per day, morning, midday and evening, and after about 1850 at fixed observation hours. We use four common storminess indices: annual number of deep lows ( p < 980 hPa), the annual 95th and 99th percentile of pressure changes between two observations, and the annual number of fast absolute pressure changes (\&UDelta;p\/&UDelta;t > 16 hPa/12 h). It turns out that the 1980' s - mid 1990' s were a period of enhanced storminess, mainly seen in the Stockholm record, but his period is within the natural variability of the records. Thus, there are no robust signs of any long-term trend in the storminess indices. Storminess is during the entire historical period remarkably stable, with no systematic change and little transient variability.

  • 43.
    Caian, Mihaela
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation2018In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 50, no 1-2, p. 423-441Article in journal (Refereed)
  • 44.
    Caian, Mihaela
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    An interannual link between Arctic sea-ice cover and the North Atlantic Oscillation (vol 50, pg 423, 2017)2018In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 50, no 1-2, p. 443-443Article in journal (Refereed)
  • 45. Cardoso Pereira, Susana
    et al.
    Marta-Almeida, Martinho
    Carvalho, Ana
    SMHI, Research Department, Air quality.
    Heat wave and cold spell changes in Iberia for a future climate scenario2017In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088Article, review/survey (Refereed)
    Abstract [en]

    : This study investigates the impacts of climate change scenario on summer heat waves’ (HWs) and winter cold spells’ (CSs) characteristics for 12 locations over the Iberian Peninsula (IP). These characteristics are duration, recovery factor and intensity. Two future time slices of the chosen scenario are studied, namely, the periods 2046–2065 and 2081–2100 which are compared with a reference climate for the recent-past (1986–2005). The RCP8.5 greenhouse gas emission scenario is considered. The minimum and maximum daily temperature were obtained for these periods through regional model simulations using the Weather and Research Forecast (WRF) model forced with the MPI-ESM-LR model. The model was validated against EOBS and SPAIN02 datasets. The model shows 90th/10th percentile temperature (i.e. thresholds to identify HW/CS) biases. Therefore, HW/CS numbers and properties were evaluated using the model’s respective thresholds. HW/CS numbers and characteristics were also compared between the model and EOBS derived data. Probability density functions (PDFs) of the duration, recovery factor and intensity show significant changes in the mean and variance for the summer HWs. Differences, between future and recent-past climate in the extremes are evaluated by the 95th percentile which show an increase in the duration and intensity of the HWs for the future time slices. Very few CSs were detectable in the mid-term future (2046–2065) and none in the long-term future (2080–2100), except for Barcelona. For most locations, the CS for the future are of smaller duration and intensity. The PDF of the recovery factor suggests smaller absolute differences between the minimum and maximum temperature during winter which is also confirmed by the percentile analysis. The increase in the duration and intensity of HWs is greater in the long-term future than in the mid-term future, pointing for a warmer IP with more and longer HWs towards the end of the XXI century

  • 46.
    Caron, Louis-Philippe
    et al.
    SMHI, Research Department, Climate research - Rossby Centre. Climate Forecasting Unit, Institut Cátála de Ciènces del clima (IC3).
    Boudreault, Mathieu
    Bruyere, Cindy L.
    Changes in large-scale controls of Atlantic tropical cyclone activity with the phases of the Atlantic multidecadal oscillation2015In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 44, no 7-8, p. 1801-1821Article in journal (Refereed)
    Abstract [en]

    Atlantic tropical cyclone activity is known to oscillate between multi-annual periods of high and low activity. These changes have been linked to the Atlantic multidecadal oscillation (AMO), a mode of variability in Atlantic sea surface temperature which modifies the large-scale conditions of the tropical Atlantic. Cyclone activity is also modulated at higher frequencies by a series of other climate factors, with some of these influences appearing to be more consistent than others. Using the HURDAT2 database and a second set of tropical cyclone data corrected for possible missing storms in the earlier part of the record, we investigate, through Poisson regressions, the relationship between a series of climate variables and a series of metrics of seasonal Atlantic cyclone activity during both phases of the AMO. We find that, while some influences, such as El Nino Southern oscillation, remain present regardless of the AMO phase, other climate factors show an influence during only one of the two phases. During the negative phase, Sahel precipitation and the North Atlantic oscillation (NAO) are measured to play a role, while during the positive phase, the 11-year solar cycle and dust concentration over the Atlantic appear to be more important. Furthermore, we show that during the negative phase of the AMO, the NAO influences all our measures of tropical cyclone activity, and we go on to provide evidence that this is not simply due to changes in steering current, the mechanism by which the NAO is usually understood to impact Atlantic cyclone activity. Finally, we conclude by demonstrating that our results are robust to the sample size as well as to the choice of the statistical model.

  • 47. Caron, Louis-Philippe
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Analysing present, past and future tropical cyclone activity as inferred from an ensemble of Coupled Global Climate Models2008In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 60, no 1, p. 80-96Article in journal (Refereed)
  • 48. Caron, Louis-Philippe
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Understanding and simulating the link between African easterly waves and Atlantic tropical cyclones using a regional climate model: the role of domain size and lateral boundary conditions2012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 39, no 1-2, p. 113-135Article in journal (Refereed)
    Abstract [en]

    Using a suite of lateral boundary conditions, we investigate the impact of domain size and boundary conditions on the Atlantic tropical cyclone and african easterly Wave activity simulated by a regional climate model. Irrespective of boundary conditions, simulations closest to observed climatology are obtained using a domain covering both the entire tropical Atlantic and northern African region. There is a clear degradation when the high-resolution model domain is diminished to cover only part of the African continent or only the tropical Atlantic. This is found to be the result of biases in the boundary data, which for the smaller domains, have a large impact on TC activity. In this series of simulations, the large-scale Atlantic atmospheric environment appears to be the primary control on simulated TC activity. Weaker wave activity is usually accompanied by a shift in cyclogenesis location, from the MDR to the subtropics. All ERA40-driven integrations manage to capture the observed interannual variability and to reproduce most of the upward trend in tropical cyclone activity observed during that period. When driven by low-resolution global climate model (GCM) integrations, the regional climate model captures interannual variability (albeit with lower correlation coefficients) only if tropical cyclones form in sufficient numbers in the main development region. However, all GCM-driven integrations fail to capture the upward trend in Atlantic tropical cyclone activity. In most integrations, variations in Atlantic tropical cyclone activity appear uncorrelated with variations in African easterly wave activity.

  • 49. Caron, Louis-Philippe
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Doblas-Reyes, Francisco
    Multi-year prediction skill of Atlantic hurricane activity in CMIP5 decadal hindcasts2014In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 42, no 9-10, p. 2675-2690Article in journal (Refereed)
    Abstract [en]

    Using a statistical relationship between simulated sea surface temperature and Atlantic hurricane activity, we estimate the skill of a CMIP5 multi-model ensemble at predicting multi-annual level of Atlantic hurricane activity. The series of yearly-initialized hindcasts show positive skill compared to simpler forecasts such as persistence and climatology as well as non-initialized forecasts and return anomaly correlation coefficients of similar to 0.6 and similar to 0.8 for five and nine year forecasts, respectively. Some skill is shown to remain in the later years and making use of those later years to create a lagged-ensemble yields, for individual models, results that approach that obtained by the multi-model ensemble. Some of the skill is shown to come from persisting rather than predicting the climate shift that occur in 1994-1995. After accounting for that shift, the anomaly correlation coefficient for five-year forecasts is estimated to drop to 0.4, but remains statistically significant up to lead years 3-7. Most of the skill is shown to come from the ability of the forecast systems at capturing change in Atlantic sea surface temperature, although the failure of most systems at reproducing the observed slow down in warming over the tropics in recent years leads to an underestimation of hurricane activity in the later period.

  • 50.
    Caron, Louis-Philippe
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Vaillancourt, Paul A.
    Winger, Katja
    On the relationship between cloud-radiation interaction, atmospheric stability and Atlantic tropical cyclones in a variable-resolution climate model2013In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 40, no 5-6, p. 1257-1269Article in journal (Refereed)
    Abstract [en]

    We compare two 28-year simulations performed with two versions of the Global Environmental Multiscale model run in variable-resolution mode. The two versions differ only by small differences in their radiation scheme. The most significant modification introduced is a reduction in the ice effective radius, which is observed to increase absorption of upwelling infrared radiation and increase temperature in the upper troposphere. The resulting change in vertical lapse rate is then observed to drive a resolution-dependent response of convection, which in turn modifies the zonal circulation and induces significant changes in simulated Atlantic tropical cyclone activity. The resulting change in vertical lapse rate and its implication in the context of anthropogenic climate change are discussed.

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