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  • 401.
    Rutgersson, Anna
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Jaagus, Jaak
    Schenk, Frederik
    Stendel, Martin
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Briede, Agrita
    Claremar, Bjorn
    Hanssen-Bauer, Inger
    Holopainen, Jari
    Moberg, Anders
    Nordli, Oyvind
    Rimkus, Egidijus
    Wibig, Joanna
    Recent Change-Atmosphere2015Chapter in book (Other academic)
    Abstract [en]

    This chapter describes observed changes in atmospheric conditions in the Baltic Sea drainage basin over the past 200-300 years. The Baltic Sea area is relatively unique with a dense observational network covering an extended time period. Data analysis covers an early period with sparse and relatively uncertain measurements, a period with well-developed synoptic stations, and a final period with 30+ years of satellite data and sounding systems. The atmospheric circulation in the European/Atlantic sector has an important role in the regional climate of the Baltic Sea basin, especially the North Atlantic Oscillation. Warming has been observed, particularly in spring, and has been stronger in the northern regions. There has been a northward shift in storm tracks, as well as increased cyclonic activity in recent decades and an increased persistence of weather types. There are no long-term trends in annual wind statistics since the nineteenth century, but much variation at the (multi-)decadal timescale. There are also no long-term trends in precipitation, but an indication of longer precipitation periods and possibly an increased risk of extreme precipitation events.

  • 402.
    Rutgersson, Anna
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Net precipitation over the Baltic Sea during present and future climate conditions2002In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 22, no 1, p. 27-39Article in journal (Refereed)
    Abstract [en]

    By using a process-oriented ocean model forced with data from a gridded synoptic database, net precipitation values (precipitation minus evaporation) over the Baltic Sea are obtained. For a range of realistic meteorological forcing the average annual value obtained from an 18 yr (1981-1998) simulation ranges between 1100 and 2500 m(3) s(-1). The monthly variations are significant with the highest values occurring in early summer and even negative values in late autumn. Ice is an important factor, and the net precipitation is close to zero in the southern basins with no ice. Calculated net precipitation for a 98 yr period (1901-1998) using river runoff and maximum ice extent indicates that the investigated 18 yr period was wetter than the almost 100 yr climate mean. A realistic climate estimate of net precipitation during the 20th century is estimated to be 1500 +/-1000 m(3) s(-1). The evaluation of 2 present day regional climate simulations indicated high precipitation, low evaporation, and thus excessive net precipitation compared to the climate estimate from this investigation. When simulating the effect of increased greenhouse gases, the change in net precipitation was positive but small due to the compensating effects of increased precipitation and increased evaporation associated with increased temperature and reduced ice.

  • 403.
    Rutgersson, Anna
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Smedman, A S
    Hogstrom, U
    Use of conventional stability parameters during swell2001In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 106, no C11, p. 27117-27134Article in journal (Refereed)
    Abstract [en]

    The situation with swell is of climatological importance over the Baltic Sea since swell is present during as much as 40% of the time. In this study, two periods with unstable and two periods with stable stratification and wind following swell are investigated. Data are taken at a small flat island in the Baltic Sea. During unstable stratification the turbulent structure shows great resemblance to the free convective boundary layer and scales with the boundary layer height. Since surface heat flux is too small to support the high levels of turbulence present, inactive turbulence is probably the dominating source. For the stably stratified layer, there are smaller differences between data with and without swell. The turbulence is mainly transported upward into the atmosphere with the aid of pressure fluctuations induced by the waves. For most of the data with swell the gradients are smaller than for growing sea. During unstable conditions the wind gradients are negative, indicating the presence of a wave-driven wind. The gradients increase with increasing height above the surface. The drag coefficient is smaller than is usually found for both stable and unstable stratification and varies very little with wind and stratification. There are only small variations in the heat transfer coefficients with changing stratification, but they are significantly different for stable and unstable stratification.

  • 404.
    Rutgersson, Anna
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Smedman, A S
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    Measured and simulated latent and sensible heat fluxes at two marine sites in the Baltic Sea2001In: Boundary-layer Meteorology, ISSN 0006-8314, E-ISSN 1573-1472, Vol. 99, no 1, p. 53-84Article in journal (Refereed)
    Abstract [en]

    In this study, turbulent heat flux data from two sites within the Baltic Sea are compared with estimates from two models. The main focus is on the latent heat flux. The measuring sites are located on small islands close to the islands of Bornholm and Gotland. Both sites have a wide wind direction sector with undisturbed over-water fetch. Mean parameters and direct fluxes were measured on masts during May to December 1998. The two models used in this study are the regional-scale atmospheric model HIRLAM and the ocean model PROBE-Baltic. It is shown that both models overestimate the sensible and latent heat fluxes. The overestimation can, to a large extent, be explained by errors in the air-water temperature and humidity differences. From comparing observed and modelled data, the estimated 8-month mean errors in temperature and humidity are up to 1 degreesC and 1 g kg(-1),respectively. The mean errors in the sensible and latent heat fluxes for the same period are approximately 15 and 30 W m(-2), respectively. Bulk transfer coefficients used for calculating heat and humidity fluxes at the surface were shown to agree rather well with the measurements, at least for the unstable data. For stable stratification, the scatter in data is generally large, and it appears that the bulk formulation chosen overestimates turbulent heat fluxes.

  • 405. Rutter, Nick
    et al.
    Essery, Richard
    Pomeroy, John
    Altimir, Nuria
    Andreadis, Kostas
    Baker, Ian
    Barr, Alan
    Bartlett, Paul
    Boone, Aaron
    Deng, Huiping
    Douville, Herve
    Dutra, Emanuel
    Elder, Kelly
    Ellis, Chad
    Feng, Xia
    Gelfan, Alexander
    Goodbody, Angus
    Gusev, Yeugeniy
    Gustafsson, David
    Hellstroem, Rob
    Hirabayashi, Yukiko
    Hirota, Tomoyoshi
    Jonas, Tobias
    Koren, Victor
    Kuragina, Anna
    Lettenmaier, Dennis
    Li, Wei-Ping
    Luce, Charlie
    Martin, Eric
    Nasonova, Olga
    Pumpanen, Jukka
    Pyles, R. David
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Sandells, Melody
    Schaedler, Gerd
    Shmakin, Andrey
    Smirnova, Tatiana G.
    Staehli, Manfred
    Stoeckli, Reto
    Strasser, Ulrich
    Su, Hua
    Suzuki, Kazuyoshi
    Takata, Kumiko
    Tanaka, Kenji
    Thompson, Erin
    Vesala, Timo
    Viterbo, Pedro
    Wiltshire, Andrew
    Xia, Kun
    Xue, Yongkang
    Yamazaki, Takeshi
    Evaluation of forest snow processes models (SnowMIP2)2009In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 114, article id D06111Article, review/survey (Refereed)
    Abstract [en]

    Thirty-three snowpack models of varying complexity and purpose were evaluated across a wide range of hydrometeorological and forest canopy conditions at five Northern Hemisphere locations, for up to two winter snow seasons. Modeled estimates of snow water equivalent (SWE) or depth were compared to observations at forest and open sites at each location. Precipitation phase and duration of above-freezing air temperatures are shown to be major influences on divergence and convergence of modeled estimates of the subcanopy snowpack. When models are considered collectively at all locations, comparisons with observations show that it is harder to model SWE at forested sites than open sites. There is no universal "best'' model for all sites or locations, but comparison of the consistency of individual model performances relative to one another at different sites shows that there is less consistency at forest sites than open sites, and even less consistency between forest and open sites in the same year. A good performance by a model at a forest site is therefore unlikely to mean a good model performance by the same model at an open site (and vice versa). Calibration of models at forest sites provides lower errors than uncalibrated models at three out of four locations. However, benefits of calibration do not translate to subsequent years, and benefits gained by models calibrated for forest snow processes are not translated to open conditions.

  • 406.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    CO2- and aerosol-induced changes in vertically integrated zonal momentum budget in a GCM experiment1998In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 11, no 4, p. 625-639Article in journal (Refereed)
    Abstract [en]

    The German Climate Computing Center recently conducted a model experiment in which separate runs simulate the climatic response to increasing CO2 alone and to increasing CO2 together with direct radiative forcing by sulfate aerosols. One of the variables that shows interesting differences between the different runs is the nearsurface zonal-mean zonal wind. As compared with the control run, the midlatitude surface westerlies intensify and shift poleward in the CO2-only run in both hemispheres in both the northern winter (DJF) and summer (JJA). However, the aerosol forcing moderates these changes in general and, in particular, reverses the pattern of change in the Northern Hemisphere in JJA. Consistent differences between the various runs occur in the meridional distribution of sea level pressure. The origin of these simulated changes is studied by using the vertically integrated zonal-mean zonal momentum budget, utilizing the intimate linkage between the low-level wind and the surface stress and the close time-mean balance between the surface stress and the other terms in the budget. Regardless of the forcing used, momentum convergence in transient eddies is found to be the dominant agent of change in the extratropical Southern Hemisphere and in the Northern Hemisphere midlatitudes in JJA, In particular, the changes in the contribution of high-pass transients are relatively large and they seem to be qualitatively traceable to the changes in the tropospheric meridional temperature gradient. In the northern extratropics in DJE stationary eddies make an even larger contribution than the transients.

  • 407.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    CO2-induced changes in atmospheric angular momentum in CMIP2 experiments2003In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 16, no 1, p. 132-143Article in journal (Refereed)
    Abstract [en]

    The response of atmospheric angular momentum to a gradual doubling of CO2 is studied using 16 model experiments participating in the second phase of the Coupled Model Intercomparison Project (CMIP2). The relative angular momentum associated with atmospheric zonal winds increases in all but one of the models, although the magnitude of the change varies widely. About 90% of the 16-model mean increase comes from increasing westerly winds in the stratosphere and the uppermost low-latitude troposphere above 200 hPa. This increase in westerly winds reflects a steepening of the meridional temperature gradient near the tropopause and in the upper troposphere. The simulated temperature gradient at this height increases partly as an indirect consequence of the poleward decrease in the tropopause height, and partly because convection induces a maximum in warming in the tropical upper troposphere. The change in the omega angular momentum associated with the surface pressure distribution is in most models smaller than the change in the relative angular momentum, although its exact value is sensitive to the method of calculation.

  • 408.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    CO2-induced changes in interannual temperature and precipitation variability in 19 CMIP2 experiments2002In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 15, no 17, p. 2395-2411Article in journal (Refereed)
    Abstract [en]

    CO2-induced changes in the interannual variability of monthly surface air temperature and precipitation are studied using 19 model experiments participating in the second phase of the Coupled Model Intercomparison Project (CMIP2). The magnitude of variability in the control runs appears generally reasonable, but it varies a great deal between different models, almost all of which overestimate temperature variability on low-latitude land areas. In most models the gradual doubling of CO2 leads to a decrease in temperature variability in the winter half-year in the extratropical Northern Hemisphere and over the high-latitude Southern Ocean. Over land in low latitudes and in northern midlatitudes in summer, a slight tendency toward increased temperature variability occurs. The standard deviation of monthly precipitation increases, on average, where the mean precipitation increases but also does so in some areas where the mean precipitation decreases slightly. The coefficient of variation of precipitation (i.e., the ratio between the standard deviation and the mean) also tends to increase in most areas, especially where the mean precipitation decreases. However, the changes in variability are less similar between the 19 experiments than the changes in mean temperature and precipitation, at least partly because they have a much lower signal-to-noise ratio. In addition, the changes in the standard deviation of monthly temperature are generally much smaller than the time-mean warming, which suggests that future changes in the extremes of interannual temperature variability will be largely determined by the latter.

  • 409.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    CO2-induced climate change in CMIP2 experiments: Quantification of agreement and role of internal variability2001In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 14, no 9, p. 2088-2104Article in journal (Refereed)
    Abstract [en]

    CO2-induced changes in surface air temperature, precipitation, and sea level pressure are compared between model experiments participating in the second phase of the Coupled Model Intercomparison Project (CMIP2). A statistical formalism is applied, in which the average squared amplitude of the simulated climate changes is divided into a common signal and variances associated with internal variability and model differences. In the 20-yr period centered at the doubling of CO2 and for a set of 14-15 models, the dimensionless global relative agreement on gridbox-scale annual mean climate changes is 0.89 for surface air temperature but only 0.22 for precipitation and 0.46 for sea level pressure. A majority of the interexperiment differences are attributed to model differences; the contribution of internal variability to the differences in change is estimated as 16% for temperature, 34% for precipitation, and 32% for sea level pressure. For seasonal rather than annual climate changes, the agreement is lower and the contribution of internal variability to the interexperiment variance larger. Likewise, the relative agreement is worse and internal variability in relative terms more important earlier during the transient experiments than around the doubling of CO2. Conversely, when climate changes are averaged over larger areas than individual grid boxes, the relative agreement improves with increasing averaging domain (especially with precipitation and temperature) and the impact of internal variability decreases.

  • 410.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    CO2-induced climate change in northern Europé: comparison of 12 CMIP2 experiments.2000Report (Other academic)
    Abstract [en]

    The results of 12 coupled atmosphere-ocean general circulation model experiments participating in the second phase of the Coupled Model Intercomparison Project (CMIP2) are studied with focus on the area of northern Europe. The variables considered are surface air temperature, precipitation and sea level pressure. The 80-year control simulations are first compared with observational estimates of the present climate. Several aspects of the simulated CO2-induced climate changes, defined by subtracting the control run  seasonal or annual means from 20-year perturbation run means around the transient doubling of CO2, are then studied. The common features and individual variations in the simulated climate change are documented. Particular attention is put on expressing the interexperiment agreement in quantitative terms and on estimating the relative contribution of model- simulated internal variability to the interexperiment variance. For that purpose, a new statistical framework is developed. Finally, an attempt is made to statistically relate the interexperiment differences in the simulated climate change in northern Europe to aspects of the control climates, global climate change and some of the basic model characteristics.

    A summary of the main findings is given in the last section of the report.

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  • 411.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Internal variability as a cause of qualitative intermodel disagreement on anthropogenic climate changes1999In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 64, no 1-2, p. 1-13Article in journal (Refereed)
    Abstract [en]

    The qualitative agreement of two climate models, HADCM2 and ECHAM3, on the response of surface climate to anthropogenic climate forcing in the period 2020-2049 is studied. Special attention is paid to the role of internal climate variability as a source of intermodel disagreement. After illustrating the methods in an intermodel comparison of simulated changes in June-August mean precipitation, some global statistics are presented. Excluding surface air temperature, the four-season mean proportion of areas in which the two models agree on the sign of the climatic response is only 53-60% both for increases in CO2 alone and for increases in CO2 together with direct radiative forcing by sulphate aerosols, but somewhat larger, 59-70% for the separate aerosol effect. In areas where the response is strong (at least twice the standard error associated with internal variability) in both models, the agreement is better and the contrast between the different forcings becomes more marked. The proportion of agreement in such areas is 57-75% for the response to increases in CO2 alone, 64-84% for the response to combined CO2 and aerosol forcing, and as high as 88-94% for the separate aerosol effect. The relatively good intermodel agreement for aerosol-induced climate changes is suggested to be associated with the uneven horizontal distribution of aerosol forcing.

  • 412.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Model-simulated CO2-induced changes in seasonal precipitation extremes2002In: INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE, 2002, p. 66-Conference paper (Other academic)
  • 413.
    Räisänen, Jouni
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Alexandersson, Hans
    SMHI.
    A probabilistic view on recent and near future climate change in Sweden2003In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 55, no 2, p. 113-125Article in journal (Refereed)
    Abstract [en]

    The decade 1991-2000 was warm and wet in Sweden, with 10-station mean temperature 0.8 degreesC above and 20-station mean precipitation 6% above the mean for 1961-1990. Here we study the question if such changes should be seen as a symptom of anthropogenic climate change or if they might be of purely natural origin. Using the control simulations of 19 atmosphere-ocean general circulation models and taking into account difference's between the simulated and observed interannual variability, we estimate that the recent increase in temperature and that in precipitation had both about a 6-7% chance to occur solely as a result of natural variability. Using the corresponding simulations with increasing CO2, we further estimate that the anthropogenic forcing raised the probability of the observed changes to occur to 23% for the increase in temperature and to 14% for the increase in precipitation. About half of the warming and about 30% of the increase in precipitation appear to be explained by anthropogenic forcing. The seasonal aspects of observed and simulated climate change are also discussed, with special emphasis on winter, when the observed warming has been much larger than expected from the model simulations. Finally, a probabilistic forecast for the Swedish climate in the first decade of the 21st century suggests a 95% (87%) possibility of warmer (wetter) annual mean conditions than in 1961-1990 on the average. One of the caveats in our analysis is that the model simulations exclude variations in solar and volcanic activity, the effects of which might not be fully covered by our resealing of interannual variability.

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  • 414.
    Räisänen, Jouni
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Simulation of present-day climate in Northen Europé in the HadCM2 OAGCM1998Report (Other academic)
    Abstract [en]

    The performance of a global coupled atmosphere-ocean general circulation model, HadCM2, in simulating present-day climate in Sweden and Northern Europe is studied. The study is motivated by the use of HadCM2 within the SWEdish regional CLimate Modelling programme SWECLIM. In particular, HadCM2 provides the boundary data for the first regional high-resolution climate simulations conducted at the Rossby Centre.

    HadCM2 is probably one of the best present global climate models, and several aspects of the simulated control climate are in reasonable agreement with observations. However, some quantitative shortcomings are also evident. In Northern Europe, the simulated summer temperatures are a few degrees colder than those observed, and their interannual variability appears too large. In winter, a local warm bias occurs around the Baltic Sea, which is too warm to get an ice cover in the model. The effect of the Scandinavian Mountains on the distribution of precipitation is distorted by the model's modest (2.5° lat x 3.75° lon) resolution. The simulated total cloudiness generally exceeds that observed.

    In comparing the model results with the records of individual climate stations, the first problem is to derive the model-simulated value at the station location from the original discrete grid box values. Several choices of doing this are examined and, at least in comparison with observed temperature and precipitation at Swedish stations, the conclusions frequently depend on how the model-simulated station value is defined.

    It is also studied how the climate in the 10-year HadCM2 control run used for dynamical downscaling at the Rossby Centre differs from a longer (240-year) control run made with the same model. In most cases, the differences between the 10-year and 240-year runs are smaller than those between the former and observations. Nevertheless, some of these differences are large enough to be kept in mind when comparing the 10-year control run with, for example, a similar run with increased CO2.

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  • 415.
    Räisänen, Jouni
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, U
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Willen, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    European climate in the late twenty-first century: regional simulations with two driving global models and two forcing scenarios2004In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 22, no 1, p. 13-31Article in journal (Refereed)
    Abstract [en]

    A basic analysis is presented for a series of regional climate change simulations that were conducted by the Swedish Rossby Centre and contribute to the PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects) project. For each of the two driving global models HadAM3H and ECHAM4/OPYC3, a 30-year control run and two 30-year scenario runs (based on the SRES A2 and B2 emission scenarios) were made with the regional model. In this way, four realizations of climate change from 1961-1990 to 2071-2100 were obtained. The simulated changes are larger for the A2 than the B2 scenario (although with few qualitative differences) and in most cases in the ECHAM4/OPYC3-driven (RE) than in the HadAM3H-driven (RH) regional simulations. In all the scenario runs, the warming in northern Europe is largest in winter or late autumn. In central and southern Europe, the warming peaks in summer when it locally reaches 10 degreesC in the RE-A2 simulation and 6-7 degreesC in the RH-A2 and RE-B2 simulations. The four simulations agree on a general increase in precipitation in northern Europe especially in winter and on a general decrease in precipitation in southern and central Europe in summer, but the magnitude and the geographical patterns of the change differ markedly between RH and RE. This reflects very different changes in the atmospheric circulation during the winter half-year, which also lead to quite different simulated changes in windiness. All four simulations show a large increase in the lowest minimum temperatures in northern, central and eastern Europe, most likely due to reduced snow cover. Extreme daily precipitation increases even in most of those areas where the mean annual precipitation decreases.

  • 416.
    Räisänen, Jouni
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Graham, Phil
    SMHI, Professional Services.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    GCM driven simulations of recent and future climate with the Rossby Centre coupled atmosphere - Baltic Sea regional climate model RCAO2003Report (Other academic)
    Abstract [en]

    A series of six general circulation model (GCM) driven regional climate simulations made at the Rossby Centre, SMHI, during the year 2002 are documented. For both the two driving GCMs HadAM3H andECHAM4/OPYC3, a 30-year (1961-1990) control run and two 30-year (2071-2100) scenario runs have been made. The scenario runs are based on the IPCC SRES A2 and B2 forcing scenarios. These simulations were made at 49 km atmospheric resolution and they are part of the European PRUDENCE project.Many aspects of the simulated control climates compare favourably with observations, but some problems are also evident. For example, the simulated cloudiness and precipitation appear generally too abundant in northern Europe (although biases in precipitation measurements complicate the interpretation), whereas too clear and dry conditions prevail in southern Europe. There is a lot of similarity between the HadAM3Hdriven (RCAO-H) and ECHAM4/OPYC3-driven (RCAO-E) control simulations, although the problems associated with the hydrological cycle and cloudiness are somewhat larger in the latter.The simulated climate changes (2071-2100 minus 1961-1990) depend on both the forcing scenario (the changes are generally larger for A2 than B2) and the driving global model (the largest changes tend to occur in RCAO-E). In all the scenario simulations, the warming in northern Europe is largest in winter or autumn. In central and southern Europe, the warming peaks in summer and reaches in the RCAO-E A2 simulation locally 10°C. The four simulations agree on a general increase in precipitation in northern Europe especiallyin winter and on a general decrease in precipitation in southern and central Europe in summer, but the magnitude and the geographical patterns of the change differ a lot between RCAO-H and RCAO-E. Thisreflects very different changes in the atmospheric circulation during the winter half-year, which also have a large impact on the simulated changes in windiness. A very large increase in the lowest minimumtemperatures occurs in a large part of Europe, most probably due to reduced snow cover. Extreme daily precipitation increases even in most of those areas where the mean annual precipitation decreases.

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  • 417.
    Räisänen, Jouni
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Joelsson, Rune
    SMHI, Research Department, Climate research - Rossby Centre.
    Changes in average and extreme precipitation in two regional climate model experiments2001In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 53, no 5, p. 547-566Article in journal (Refereed)
    Abstract [en]

    Two regional climate model experiments for northern and central Europe are studied focussing on greenhouse gas-induced changes in heavy precipitation. The average yearly maximum one-day precipitation P-max shows a general increase in the A hole model domain in both experiments, although the mean precipitation P-mcan decreases in the southern part of the area, especially in one of the experiments. The average yearly maximum six-hour precipitation increases even more than the one-day P-max suggesting a decrease in the timescale of heavy precipitation. The contrast between the P-max, and P-max changes in the southern part of the domain and the lack of such a contrast further north are affected by changes in wet-day frequency that stem, at least in part. from changes in atmospheric circulation. However, the yearly extremes of precipitation exhibit a larger percentage increase than the average wet-day precipitation. The signal-to-noise aspects of the model results are also studied in some detail. The 44 km grid-box-scaie changes in P-max are very heavily affected by inter-annual variability, with an estimated standard error ;of about 20% for the 10-year mean changes. However. the noise in P-max decreases sharply toward larger horizontal scales, and large-area mean changes in P-max can be estimated with similar accuracy to those in P-mcan Although a horizontal averaging of model results smooths out the small-scale details in the true climate change signal as well, this disadvantage is, in the case of P-max changes, much smaller than the advantage of reduced noise.

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  • 418.
    Räisänen, Jouni
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Palmer, T N
    A probability and decision-model analysis of a multimodel ensemble of climate change simulations2001In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 14, no 15, p. 3212-3226Article in journal (Refereed)
    Abstract [en]

    Because of the inherent uncertainties in the computational representation of climate and because of unforced chaotic climate variability, it is argued that climate change projections should be expressed in probabilistic form. In this paper, 17 Coupled Model Intercomparison Project second-phase experiments sharing the same gradual increase in atmospheric CO2 are treated as a probabilistic multimodel ensemble projection of future climate. Tools commonly used for evaluation of probabilistic weather and seasonal forecasts are applied to this climate change ensemble. The probabilities of some temperature- and precipitation-related events defined for 20-yr seasonal means of climate are first studied. A cross-verification exercise is then used to obtain an upper estimate of the quality of these probability forecasts in terms of Brier skill scores, reliability diagrams, and potential economic value. Skill and value estimates are consistently higher for temperature- related events (e.g., will the 20-yr period around the doubling of CO2 be at least 1 degreesC warmer than the present?) than for precipitation-related events (e.g., will the mean precipitation decrease by 10% or more?). For large enough CO2 forcing, however, probabilistic projections of precipitation-related events also exhibit substantial potential economic value for a range of cost-loss ratios. The treatment of climate change information in a probabilistic rather than deterministic manner (e.g., using the ensemble consensus forecast) can greatly enhance its potential value.

  • 419.
    Räisänen, Jouni
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Downscaling of greenhouse gas induced climate change in two GCMs with the Rossby Centre regional climate model for northern Europe2001In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 53, no 2, p. 168-191Article in journal (Refereed)
    Abstract [en]

    Two 2 x 10-year climate change experiments made with the Rossby Centre regional Atmospheric climate model(RCA) are reported. These two experiments are driven by boundary data from two global climate change simulations, one made with HadCM2 and the other with ECKAM4/OPYC3, in which the global mean warming is virtually the same, 2.6 degreesC. The changes in mean temperature and precipitation show similarities (including broadly the same increase in temperature and in northern Europe a general increase in annual precipitation) as well as differences between the two RCA experiments. These changes are strongly governed by the driving GCM simulations. Even on the RCA grid box scale, the differences in change between RCA and the driving GCM are generally smaller than the differences between the two GCMs. Typically about a half of the local differences between the two RCA simulations are attributed to noise generated by internal variability, which also seems to explain a substantial part of the RCA-GCM differences particularly for precipitation change. RCA includes interactive model components for the Baltic Sea and inland lakes of northern Europe. The simulated changes in these water bodies are discussed with emphasis on the wintertime ice conditions. Comparison with an earlier RCA experiment indicates that a physically consistent treatment of these water bodies is also of importance for the simulated atmospheric climate change.

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  • 420.
    Räisänen, Jouni
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Bringfelt, Björn
    SMHI.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    The First Rossby Centre Regional Climate Scenario - Dynamical Downscaling of CO2-induced Climate Change in the HadCM2 GCM1999Report (Other academic)
    Abstract [en]

    Results of the first 10-year climate change experiment made with the Rossby Centre regional climate model (RCA) are described. The boundary data for this experiment were derived from two simulations with the .global HadCM2 ocean-atmosphere GCM, a control run anda scenario run with 150% higher equivalent CO2 and 2.6°C higher global mean surface air temperature.

    Some of the climate changes (scenario run - control run) simulated by RCA are substantial. The annual mean temperature in the Nordic region increases by roughly 4°C, with largest warming in winter. Annual absolute minimum temperatures increase even more than the winter mean temperature, presumably due to greatly reduced snow and ice cover. Precipitation is also simulated to increase in northern Europe, locally by 40% in the annual mean in Swedish Lappland. The larger time mean precipitation is accompanied by a marked increase in the number of days with heavy precipitation.

    The large-scale temperature and precipitation changes simulated by RCA are similar to those in HadCM2. Unlike HadCM2, however, RCA simulates a strong local maximum of wintertime warming over the northern parts of the Baltic Sea. This is caused by radically reduced ice cover, but the crude treatment of the Baltic Sea and its ice even in RCA complicates the interpretation. Large differences between the models occur in the simulated changes of winter mean total cloudiness and near-surface wind speed, demonstrating the sensitivity of these to differences in resolution and/or physical parameterizations.

    The significance of the simulated climate changes against interannual variability depends on the parameter considered. Of highest statistical significance are changes in surface air temperature and strongly temperature-related variables such as snow and ice cover. In general, changes in annual means are more commonly significant than those in seasonal means. The impact of the limited averaging period is also studied by comparing the 10-year mean climate changes simulated by the driving HadCM2 mode! with climate changes inferred from much longer HadCM2 integrations.

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  • 421. Räisänen, P.
    et al.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Räisänen, J.
    Modification of the HIRLAM radiation scheme for use in the Rossby Centre regional atmospheric climate model.2000Report (Other academic)
  • 422.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bringfelt, Björn
    SMHI, Research Department, Climate research - Rossby Centre.
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    The role of aerodynamic roughness for runoff and snow evaporation in land-surface schemes - comparison of uncoupled and coupled simulations2003In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 38, no 1-2, p. 93-99Article in journal (Refereed)
    Abstract [en]

    This paper describes the impact of changes in aerodynamic roughness length for snow-covered surfaces in a land-surface scheme (LSS) on simulated runoff and evapotranspiration. The study was undertaken as the LSS in question produced widely divergent results in runoff, depending on whether it was used in uncoupled one-dimensional simulations forced by observations from the PILPS2e project, or in three-dimensional simulations coupled to an atmospheric model. The LSS was applied in two versions (LSS1 and LSS2) for both uncoupled and coupled simulations, where the only difference between the two versions was in the roughness length of latent heat used over snow-covered surfaces. The results show that feedback mechanisms in temperature and humidity in the coupled simulations were able to compensate for deficiencies in parameterizations and therefore, LSS1 and LSS2 yielded similar runoff results in this case. Since such feedback mechanisms are absent in uncoupled simulations, the two LSS versions produced very different runoff results in the uncoupled case. However, the magnitude of these feedback mechanisms is small compared to normal variability in temperature and humidity and cannot, by themselves, reveal any deficiencies in a parameterization. The conclusion we obtained is that the magnitude of the aerodynamic resistance is important to correctly simulate fluxes and runoff, but feedback mechanisms in a coupled model can partly compensate for errors. (C) 2003 Elsevier Science B.V. All rights reserved.

  • 423.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Gollvik, Stefan
    Meterologi.
    Kupiainen, Marco
    SMHI, Research Department, Climate research - Rossby Centre.
    Kourzeneva, Ekaterina 
    Finnish Meteorological Institute, (FMI), Helsinki, Finland.
    van de Berg, Willem Jan
    Institute for Marine and Atmospheric research Utrecht University, (IMAU), the Netherlands.
    The surface processes of the Rossby Centre regional atmospheric climate model (RCA4)2015Report (Other academic)
    Abstract [en]

    This report describes the physical processes as part of the surface scheme in the Rossby Centre Regional Atmospheric Climate Model (RCA4). Or more strictly for the version used for the CORDEX downscalings with RCA4. The most important aspects of the surface scheme that are changed with respect to RCA3 are that (i) a new physiography data base is used, (ii) the number of soil layers with respect to soil moisture are increased from two to three and there is also separate soil columns with respect to soil water under forest and open land, respectively, (iii) an exponential root distribution is used, (iv) the density of organic carbon is used to modify soil properties, (v) the prognostic snow albedo is modified to perform better in cold-climate conditions, (vi) Flake is introduced as lake model and lake depth is defined from a global lake-depth data base, (vii) the dynamic vegetation model LPJ-GUESS is introduced for vegetation-climate feedback studies.

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  • 424.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Gollvik, Stefan
    Meterologi.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    The land-surface scheme of the Rossby Centre regional atmospheric climate model (RCA3)2006Report (Other academic)
    Abstract [en]

    This report describes the physical processes as part of the Land-Surface Scheme (LSS) in the Rossby Centre Regional Atmospheric Climate Model (RCA3). The LSS is a tiled scheme with the three main tiles with respect to temperature: forest, open land, and snow. The open land tile is divided into a vegetated and a bare soil part for latent heat flux calculations. The individual fluxes of heat and momentum from these tiles are weighted in order to obtain grid-averaged values at the lowest atmospheric model level according to the fractional areas of the tiles. The forest tile is internally divided into three sub-tiles: forest canopy, forest floor soil, and snow on forest floor. All together this gives three to five different surface energy balances depending on if snow is present or not.The soil is divided into five layers with respect to temperature, with a no-flux boundary condition at three meters depth, and into two layers with respect to soil moisture, with a maximum depth of just above 2.2 meters. Runoff generated at the bottom of the deep soil layer may be used as input to a routing scheme.In addition to the soil moisture storages there are six more water storages in the LSS: interception of water on open land vegetation and on forest canopy, snow water equivalent of open land and forest snow, and liquid water content in both snow storages.Diagnostic variables of temperature and humidity at 2m and wind at 10m are calculated individually for each tile.

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  • 425.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Gollvik, Stefan
    SMHI, Research Department, Meteorology.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Jansson, Christer
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    The Rossby Centre Regional Climate model RCA3: model description and performance2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, no 1, p. 4-23Article in journal (Refereed)
  • 426.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Gollvik, Stefan
    SMHI, Research Department, Meteorology.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    The Rossby Centre Regional Climate Model RCA3: Model description and performance2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63A, no 1, p. 4-23Article in journal (Refereed)
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  • 427.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kourzeneva, Ekaterina
    Mironov, Dmitrii
    The impact of lakes on the European climate as simulated by a regional climate model2010In: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 15, no 2, p. 113-129Article in journal (Refereed)
    Abstract [en]

    The impact of lakes on the European climate is considered by analysing two 30-year regional climate model (RCM) simulations. The RCM applied is the Rossby Centre regional climate model RCA3.5. A simulation where all lakes in the model domain are replaced by land surface is compared with a simulation where the effect of lakes is accounted for through the use of the lake model FLake coupled to RCA. The difference in 2m open-land air temperature between the two simulations shows that lakes induce a warming on the European climate for all seasons. The greatest impact is seen during autumn and winter over southern Finland and western Russia where the warming exceeds 1 C. Locally, e.g. over southern Finland and over Lake Ladoga, the convective precipitation is enhanced by 20%-40% during late summer and early autumn while it is reduced by more than 70% over Lake Ladoga during early summer.

  • 428.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Tjernstrom, M
    Mesoscale flow modification induced by land-lake surface temperature and roughness differences2001In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 106, no D12, p. 12419-12435Article in journal (Refereed)
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  • 429.
    Samuelsson, Patrick
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Applying the Rossby Centre Regional Climate Model (RCA3.5) over the ENSEMBLES-AMMA region: Sensitivity studies and future scenarios2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M., 2009, p. 217-218Conference paper (Other academic)
  • 430. Sanchez, E.
    et al.
    Solman, S.
    Remedio, A. R. C.
    Berbery, H.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Da Rocha, R. P.
    Mourao, C.
    Li, L.
    Marengo, J.
    de Castro, M.
    Jacob, D
    Regional climate modelling in CLARIS-LPB: a concerted approach towards twentyfirst century projections of regional temperature and precipitation over South America2015In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 45, no 7-8, p. 2193-2212Article in journal (Refereed)
    Abstract [en]

    The results of an ensemble of regional climate model (RCM) simulations over South America are presented. This is the first coordinated exercise of regional climate modelling studies over the continent, as part of the CLARIS-LPB EU FP7 project. The results of different future periods, with the main focus on (2071-2100) is shown, when forced by several global climate models, all using the A1B greenhouse gases emissions scenario. The analysis is focused on the mean climate conditions for both temperature and precipitation. The common climate change signals show an overall increase of temperature for all the seasons and regions, generally larger for the austral winter season. Future climate shows a precipitation decrease over the tropical region, and an increase over the subtropical areas. These climate change signals arise independently of the driving global model and the RCM. The internal variability of the driving global models introduces a very small level of uncertainty, compared with that due to the choice of the driving model and the RCM. Moreover, the level of uncertainty is larger for longer horizon projections for both temperature and precipitation. The uncertainty in the temperature changes is larger for the subtropical than for the tropical ones. The current analysis allows identification of the common climate change signals and their associated uncertainties for several subregions within the South American continent.

  • 431.
    Schimanke, Semjon
    et al.
    SMHI, Research Department, Oceanography.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    A regional climate model simulation over the Baltic Sea region for the last Millennium2011Report (Other academic)
    Abstract [en]

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

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  • 432.
    Schimanke, Semjon
    et al.
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    The climate in the Baltic Sea region during the last millennium simulated with a regional climate model2012In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 8, no 5, p. 1419-1433Article in journal (Refereed)
    Abstract [en]

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

  • 433. Schroeder, Marc
    et al.
    van Lipzig, Nicole P. M.
    Ament, Felix
    Chaboureau, Jean-Pierre
    Crewell, Susanne
    Fischer, Juergen
    Matthias, Volker
    van Meijgaard, Erik
    Walther, Andi
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Model predicted low-level cloud parameters Part II: Comparison with satellite remote sensing observations during the BALTEX Bridge Campaigns2006In: Atmospheric research, ISSN 0169-8095, E-ISSN 1873-2895, Vol. 82, no 1-2, p. 83-101Article in journal (Refereed)
    Abstract [en]

    A pressing task in numerical weather prediction and climate modelling is the evaluation of modelled cloud fields. Recent progress in spatial and temporal resolution of satellite remote sensing increases the potential of such evaluation efforts. This paper presents new methodologies to compare satellite remote sensing observations of clouds and output of atmospheric models and demonstrates their usefulness for evaluation. The comparison is carried out for two MODerate resolution Imaging Spectrometer (MODIS) scenes from the BALTEX Bridge Campaigns. Both scenes are characterised by low-level clouds with a substantial amount of liquid water. Cloud cover and cloud optical thickness of five different models, LM, Wso-NH, MM5 (non-hydrostatic models), RACMO2, and RCA (regional climate models) as well as corresponding retrievals from high resolution remote sensing observations of MODIS onboard the Terra satellite form the basis of a statistical analysis to compare the data sets. With the newly introduced patchiness parameters it is possible to separate differences between the two scenes on the one hand and between the models and the satellite on the other hand. We further introduce a new approach to spatially aggregate cloud optical thickness. Generally the models overestimate cloud optical thickness which can in part be ascribed to the lack of subgrid-scale variability. However, UM underestimates the frequency of occurrence of cloud optical thickness at values around 25. Furthermore, we compare the standard operational output of the non-hydrostatic models to simulations of the same models including parameterised shallow convection. However, clear improvements in the representation of low-level clouds are not found for these models. A change of the coefficients for autoconversion in RCA shows that LWP and precipitation strongly depend on this parameter. Refined vertical resolution, implemented in RACMO2, leads to a better agreement between model and satellite but still leaves room for further improvements. In general, this study reveals deficiencies of the models in representing low-level clouds, in particular for a stratiform cloud. (c) 2006 Elsevier B.V. All rights reserved.

  • 434. Semmler, Tido
    et al.
    McGrath, Ray
    Wang, Shiyu
    SMHI, Research Department, Climate research - Rossby Centre.
    The impact of Arctic sea ice on the Arctic energy budget and on the climate of the Northern mid-latitudes2012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 39, no 11, p. 2675-2694Article in journal (Refereed)
    Abstract [en]

    The atmospheric general circulation model EC-EARTH-IFS has been applied to investigate the influence of both a reduced and a removed Arctic sea ice cover on the Arctic energy budget and on the climate of the Northern mid-latitudes. Three 40-year simulations driven by original and modified ERA-40 sea surface temperatures and sea ice concentrations have been performed at T255L62 resolution, corresponding to 79 km horizontal resolution. Simulated changes between sensitivity and reference experiments are most pronounced over the Arctic itself where the reduced or removed sea ice leads to strongly increased upward heat and longwave radiation fluxes and precipitation in winter. In summer, the most pronounced change is the stronger absorption of shortwave radiation which is enhanced by optically thinner clouds. Averaged over the year and over the area north of 70 degrees N, the negative energy imbalance at the top of the atmosphere decreases by about 10 W/m(2) in both sensitivity experiments. The energy transport across 70 degrees N is reduced. Changes are not restricted to the Arctic. Less extreme cold events and less precipitation are simulated in sub-Arctic and Northern mid-latitude regions in winter.

  • 435.
    Sheldon, Johnston, Marston
    et al.
    SMHI, Research Department, Atmospheric remote sensing.
    Eliasson, S.
    Eriksson, P.
    Forbes, R. M.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Zelinka, M. D.
    Diagnosing the average spatio-temporal impact of convective systems - Part 1: A methodology for evaluating climate models2013In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 13, no 23, p. 12043-12058Article in journal (Refereed)
    Abstract [en]

    An earlier method to determine the mean response of upper-tropospheric water to localised deep convective systems (DC systems) is improved and applied to the EC-Earth climate model. Following Zelinka and Hartmann (2009), several fields related to moist processes and radiation from various satellites are composited with respect to the local maxima in rain rate to determine their spatio-temporal evolution with deep convection in the central Pacific Ocean. Major improvements to the earlier study are the isolation of DC systems in time so as to prevent multiple sampling of the same event, and a revised definition of the mean background state that allows for better characterisation of the DC-system-induced anomalies. The observed DC systems in this study propagate westward at similar to 4 ms(-1). Both the upper-tropospheric relative humidity and the outgoing longwave radiation are substantially perturbed over a broad horizontal extent and for periods > 30 h. The cloud fraction anomaly is fairly constant with height but small maximum can be seen around 200 hPa. The cloud ice water content anomaly is mostly confined to pressures greater than 150 hPa and reaches its maximum around 450 hPa, a few hours after the peak convection. Consistent with the large increase in upper-tropospheric cloud ice water content, albedo increases dramatically and persists about 30 h after peak convection. Applying the compositing technique to EC-Earth allows an assessment of the model representation of DC systems. The model captures the large-scale responses, most notably for outgoing longwave radiation, but there are a number of important differences. DC systems appear to propagate east-ward in the model, suggesting a strong link to Kelvin waves instead of equatorial Rossby waves. The diurnal cycle in the model is more pronounced and appears to trigger new convection further to the west each time. Finally, the modelled ice water content anomaly peaks at pressures greater than 500 hPa and in the upper troposphere between 250 hPa and 500 hPa, there is less ice than the observations and it does not persist as long after peak convection. The modelled upper-tropospheric cloud fraction anomaly, however, is of a comparable magnitude and exhibits a similar longevity as the observations.

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  • 436.
    Sheldon, Johnston, Marston
    et al.
    SMHI, Research Department, Atmospheric remote sensing.
    Eriksson, P.
    Eliasson, Salomon
    SMHI, Research Department, Atmospheric remote sensing.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Forbes, R. M.
    Murtagh, D. P.
    The representation of tropical upper tropospheric water in EC Earth V22012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 39, no 11, p. 2713-2731Article in journal (Refereed)
    Abstract [en]

    Tropical upper tropospheric humidity, clouds, and ice water content, as well as outgoing longwave radiation (OLR), are evaluated in the climate model EC Earth with the aid of satellite retrievals. The Atmospheric Infrared Sounder and Microwave Limb Sounder together provide good coverage of relative humidity. EC Earth's relative humidity is in fair agreement with these observations. CloudSat and CALIPSO data are combined to provide cloud fractions estimates throughout the altitude region considered (500-100 hPa). EC Earth is found to overestimate the degree of cloud cover above 200 hPa and underestimate it below. Precipitating and non-precipitating EC Earth ice definitions are combined to form a complete ice water content. EC Earth's ice water content is below the uncertainty range of CloudSat above 250 hPa, but can be twice as high as CloudSat's estimate in the melting layer. CERES data show that the model underestimates the impact of clouds on OLR, on average with about 9 W m(-2). Regionally, EC Earth's outgoing longwave radiation can be similar to 20 W m(-2) higher than the observation. A comparison to ERA-Interim provides further perspectives on the model's performance. Limitations of the satellite observations are emphasised and their uncertainties are, throughout, considered in the analysis. Evaluating multiple model variables in parallel is a more ambitious approach than is customary.

  • 437. Siebesma, A P
    et al.
    Jakob, C
    Lenderink, G
    Neggers, R A J
    Teixeira, J
    Van Meijgaard, E
    Calvo, J
    Chlond, A
    Grenier, H
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Kohler, M
    Kitagawa, H
    Marquet, P
    Lock, A P
    Muller, F
    Olmeda, D
    Severijns, C
    Cloud representation in general-circulation models over the northern Pacific Ocean: A EUROCS intercomparison study2004In: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 130, no 604, p. 3245-3267Article in journal (Refereed)
    Abstract [en]

    The EUROCS (EUROpean Cloud Systems study) project aims to improve the treatment of cloud systems in regional and global climate and weather prediction models. This paper reports an intercomparison study of cloud representation over the Pacific Ocean for nine climate and weather prediction models. The study consists of an analysis of a June/July/August 1998 period along an idealized trajectory over the Pacific Ocean that encompasses both the ascending and descending branch of the Hadley circulation. The three cloud types that are studied by EUROCS, stratocumulus, shallow cumulus and deep-convective cloud systems, do all occur in a persistent and geographically separated way, along this trajectory. The main focus of this study is on processes related to the hydrological cycle within the Hadley circulation. These include the large-scale dynamics (i.e. the strength of the up- and downwelling branches of the Hadley cell), the cloud processes (i.e. cloud cover, cloud amounts and precipitation), and the impact of these processes on the radiation budget both at the top of the atmosphere and at the ocean's surface. In order to make a quantitative assessment, special care has been taken to select reliable observational datasets. The main conclusions are that (1) almost all models strongly underpredicted both cloud cover and cloud amount in the stratocumulus regions while (2) the situation is opposite in the trade-wind region and the tropics where cloud cover and cloud amount are overpredicted by most models. These deficiencies result in an overprediction of the downwelling surface short-wave radiation of typically 60 W m(-2) in the stratocumulus regimes and a similar underprediction of 60 W m(-2) in the trade-wind regions and in the intertropical convergence zone (ITCZ). Similar biases for the short-wave radiation were found at the top of the atmosphere, while discrepancies in the outgoing long-wave radiation are most pronounced in the ITCZ.

  • 438. Sitz, L. E.
    et al.
    Di Sante, F.
    Farneti, R.
    Fuentes Franco, Ramon
    SMHI, Research Department, Climate research - Rossby Centre.
    Coppola, E.
    Mariotti, L.
    Reale, M.
    Sannino, G.
    Barreiro, M.
    Nogherotto, R.
    Giuliani, G.
    Graffino, G.
    Solidoro, C.
    Cossarini, G.
    Giorgi, F.
    Description and evaluation of the Earth System Regional Climate Model (Reg CM-ES)2017In: Journal of Advances in Modeling Earth Systems, ISSN 1942-2466, Vol. 9, no 4, p. 1863-1886Article in journal (Refereed)
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  • 439. Skalak, Petr
    et al.
    Deque, Michel
    Belda, Michal
    Farda, Ales
    Halenka, Tomas
    Csima, Gabriella
    Bartholy, Judit
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Spiridonov, Valery
    CECILIA regional climate simulations for the present climate: validation and inter-comparison2014In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 60, no 1, p. 1-12Article in journal (Refereed)
    Abstract [en]

    We investigated high-resolution simulations of regional climate models (RCMs) driven by ERA-40 reanalyses over areas of selected European countries (Austria, Czech Republic, Hungary, Slovakia and Romania) for the period 1961-1990. RCMs were run at a spatial resolution of 10 km in the framework of the CECILIA project, and their outputs were compared with the EOBS dataset of gridded observations and RCM simulations at coarser 25 km resolution from the ENSEMBLES project to identify a possible gain from the CECILIA experiments over ENSEMBLES. Cold biases of air temperature and wet biases of precipitation dominate in the CECILIA simulations. Spatial variability and distribution of the air temperature field are well captured. The precipitation field, relative to observations, often shows inadequately small spatial variability and lowered correlations but is nevertheless comparable to the ENSEMBLES model. Inter-annual variability (IAV) of air temperature is captured differently among seasons but mostly improved in CECILIA compared with ENSEMBLES. Precipitation IAV shows a similar or worse score. The detected weaknesses found within the validation of the CECILIA RCMs are attributed to the resolution dependence of the set of physical parameterizations in the models and the choice of integration domain. The gain obtained by using a high resolution over a small domain (as in CECILIA) relative to a lower resolution (25 km) over a larger domain (as in ENSEMBLES) is clear for air temperature but limited for precipitation.

  • 440. Smith, D. M.
    et al.
    Scaife, A. A.
    Hawkins, E.
    Bilbao, R.
    Boer, G. J.
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Caron, L. -P
    Danabasoglu, G.
    Delworth, T.
    Doblas-Reyes, F. J.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Dunstone, N. J.
    Eade, R.
    Hermanson, L.
    Ishii, M.
    Kharin, V.
    Kimoto, M.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Kushnir, Y.
    Matei, D.
    Meehl, G. A.
    Menegoz, M.
    Merryfield, W. J.
    Mochizuki, T.
    Mueller, W. A.
    Pohlmann, H.
    Power, S.
    Rixen, M.
    Sospedra-Alfonso, R.
    Tuma, M.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Yang, X.
    Yeager, S.
    Predicted Chance That Global Warming Will Temporarily Exceed 1.5 degrees C2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 21, p. 11895-11903Article in journal (Refereed)
  • 441. Smith, Doug M.
    et al.
    Scaife, Adam A.
    Boer, George J.
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Doblas-Reyes, Francisco J.
    Guemas, Virginie
    Hawkins, Ed
    Hazeleger, Wilco
    Hermanson, Leon
    Ho, Chun Kit
    Ishii, Masayoshi
    Kharin, Viatcheslav
    Kimoto, Masahide
    Kirtman, Ben
    Lean, Judith
    Matei, Daniela
    Merryfield, William J.
    Mueller, Wolfgang A.
    Pohlmann, Holger
    Rosati, Anthony
    Wouters, Bert
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Real-time multi-model decadal climate predictions2013In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 41, no 11-12, p. 2875-2888Article in journal (Refereed)
    Abstract [en]

    We present the first climate prediction of the coming decade made with multiple models, initialized with prior observations. This prediction accrues from an international activity to exchange decadal predictions in near real-time, in order to assess differences and similarities, provide a consensus view to prevent over-confidence in forecasts from any single model, and establish current collective capability. We stress that the forecast is experimental, since the skill of the multi-model system is as yet unknown. Nevertheless, the forecast systems used here are based on models that have undergone rigorous evaluation and individually have been evaluated for forecast skill. Moreover, it is important to publish forecasts to enable open evaluation, and to provide a focus on climate change in the coming decade. Initialized forecasts of the year 2011 agree well with observations, with a pattern correlation of 0.62 compared to 0.31 for uninitialized projections. In particular, the forecast correctly predicted La Nia in the Pacific, and warm conditions in the north Atlantic and USA. A similar pattern is predicted for 2012 but with a weaker La Nia. Indices of Atlantic multi-decadal variability and Pacific decadal variability show no signal beyond climatology after 2015, while temperature in the Nio3 region is predicted to warm slightly by about 0.5 A degrees C over the coming decade. However, uncertainties are large for individual years and initialization has little impact beyond the first 4 years in most regions. Relative to uninitialized forecasts, initialized forecasts are significantly warmer in the north Atlantic sub-polar gyre and cooler in the north Pacific throughout the decade. They are also significantly cooler in the global average and over most land and ocean regions out to several years ahead. However, in the absence of volcanic eruptions, global temperature is predicted to continue to rise, with each year from 2013 onwards having a 50 % chance of exceeding the current observed record. Verification of these forecasts will provide an important opportunity to test the performance of models and our understanding and knowledge of the drivers of climate change.

  • 442. Soerensson, Anna A.
    et al.
    Menendez, Claudio G.
    Ruscica, Romina
    Alexander, Peter
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Projected precipitation changes in South America: a dynamical downscaling within CLARIS2010In: Meteorologische Zeitschrift, ISSN 0941-2948, E-ISSN 1610-1227, Vol. 19, no 4, p. 347-355Article in journal (Refereed)
    Abstract [en]

    Responses of precipitation seasonal means and extremes over South America in a downscaling of a Climate change scenario are assessed with the Rossby Centre Regional Atmospheric Model (RCA). The anthropogenic warming under A1B scenario influences more on the likelihood of occurrence of severe extreme events like heavy precipitation and dry spells than on the mean seasonal precipitation. The risk of extreme precipitation increases in the La Plata Basin with a factor of 1.5-2.5 during all seasons and in the northwestern part of the continent with a factor 1.5-3 in summer, while it decreases in central and northeastern Brazil during winter and spring. The maximum amount of 5-days precipitation increases by up to 50% in La Plata Basin, indicating risks of flooding. Over central Brazil and the Bolivian lowland, where present 5-days precipitation is higher, the increases are similar in magnitude and could cause less impacts. In southern Amazonia, northeastern Brazil and the Amazon basin, the maximum number of consecutive dry days increases and mean winter and spring precipitation decreases, indicating a longer dry season. In the La Plata Basin, there is no clear pattern of change for the dry spell duration.

  • 443. Soerensson, Anna A.
    et al.
    Menendez, Claudio G.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Soil-precipitation feedbacks during the South American Monsoon as simulated by a regional climate model2010In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 98, no 3-4, p. 429-447Article in journal (Refereed)
    Abstract [en]

    We summarize the recent progress in regional climate modeling in South America with the Rossby Centre regional atmospheric climate model (RCA3-E), with emphasis on soil moisture processes. A series of climatological integrations using a continental scale domain nested in reanalysis data were carried out for the initial and mature stages of the South American Monsoon System (SAMS) of 1993-92 and were analyzed on seasonal and monthly timescales. The role of including a spatially varying soil depth, which extends to 8 m in tropical forest, was evaluated against the standard constant soil depth of the model of about 2 m, through two five member ensemble simulations. The influence of the soil depth was relatively weak, with both beneficial and detrimental effects on the simulation of the seasonal mean rainfall. Secondly, two ensembles that differ in their initial state of soil moisture were prepared to study the influence of anomalously in subtropical South America as well. Finally, we calculated the soil moisture-precipitation coupling strength through comparing a ten member ensemble forced by the same space-time series of soil moisture fields with an ensemble with interactive soil moisture. Coupling strength is defined as the degree to which the prescribed boundary conditions affect some atmospheric quantity in a climate model, in this context a quantification of the fraction of atmospheric variability that can be ascribed to soil moisture anomalies. La Plata Basin appears as a region where the precipitation is partly controlled by soil moisture, especially in November and January. The continental convective monsoon regions and subtropical South America appears as a region with relatively high coupling strength during the mature phase of monsoon development dry and wet soil moisture initial conditions on the intraseasonal development of the SAMS. In these simulations the austral winter soil moisture initial condition has a strong influence on wet season rainfall over feed back upon the monsoon, not only over the Amazon region but in subtropical South America as well. Finally, we calculated the soil moisture-precipitation coupling strength through comparing a ten member ensemble forced by the same space-time series of soil moisture fields with an ensemble with interactive soil moisture. Coupling strength is defined as the degree to which the prescribed boundary conditions affect some atmospheric quantity in a climate model, in this context a quantification of the fraction of atmospheric variability that can be ascribed to soil moisture anomalies. La Plata Basin appears as a region where the precipitation is partly controlled by soil moisture, especially in November and January. The continental convective monsoon regions and subtropical South America appears as a region with relatively high coupling strength during the mature phase of monsoon development.

  • 444. Solman, Silvina A.
    et al.
    Sanchez, E.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    da Rocha, R. P.
    Li, L.
    Marengo, J.
    Pessacg, N. L.
    Remedio, A. R. C.
    Chou, S. C.
    Berbery, H.
    Le Treut, H.
    de Castro, M.
    Jacob, D.
    Evaluation of an ensemble of regional climate model simulations over South America driven by the ERA-Interim reanalysis: model performance and uncertainties2013In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 41, no 5-6, p. 1139-1157Article in journal (Refereed)
    Abstract [en]

    The capability of a set of 7 coordinated regional climate model simulations performed in the framework of the CLARIS-LPB Project in reproducing the mean climate conditions over the South American continent has been evaluated. The model simulations were forced by the ERA-Interim reanalysis dataset for the period 1990-2008 on a grid resolution of 50 km, following the CORDEX protocol. The analysis was focused on evaluating the reliability of simulating mean precipitation and surface air temperature, which are the variables most commonly used for impact studies. Both the common features and the differences among individual models have been evaluated and compared against several observational datasets. In this study the ensemble bias and the degree of agreement among individual models have been quantified. The evaluation was focused on the seasonal means, the area-averaged annual cycles and the frequency distributions of monthly means over target sub-regions. Results show that the Regional Climate Model ensemble reproduces adequately well these features, with biases mostly within +/- 2 A degrees C and +/- 20 % for temperature and precipitation, respectively. However, the multi-model ensemble depicts larger biases and larger uncertainty (as defined by the standard deviation of the models) over tropical regions compared with subtropical regions. Though some systematic biases were detected particularly over the La Plata Basin region, such as underestimation of rainfall during winter months and overestimation of temperature during summer months, every model shares a similar behavior and, consequently, the uncertainty in simulating current climate conditions is low. Every model is able to capture the variety in the shape of the frequency distribution for both temperature and precipitation along the South American continent. Differences among individual models and observations revealed the nature of individual model biases, showing either a shift in the distribution or an overestimation or underestimation of the range of variability.

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

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

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

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

  • 448. Stengel, Martin
    et al.
    Schlundt, Cornelia
    Stapelberg, Stefan
    Sus, Oliver
    Eliasson, Salomon
    SMHI, Research Department, Atmospheric remote sensing.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Meirink, Jan Fokke
    Comparing ERA-Interim clouds with satellite observations using a simplified satellite simulator2018In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 18, no 23, p. 17601-17614Article in journal (Refereed)
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  • 449. Stengel, Martin
    et al.
    Stapelberg, Stefan
    Sus, Oliver
    Schlundt, Cornelia
    Poulsen, Caroline
    Thomas, Gareth
    Christensen, Matthew
    Henken, Cintia Carbajal
    Preusker, Rene
    Fischer, Juergen
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Karlsson, Karl-Göran
    SMHI, Research Department, Atmospheric remote sensing.
    McGarragh, Gregory R.
    Proud, Simon
    Povey, Adam C.
    Grainger, Roy G.
    Meirink, Jan Fokke
    Feofilov, Artem
    Bennartz, Ralf
    Bojanowski, Jedrzej S.
    Hollmann, Rainer
    Cloud property datasets retrieved from AVHRR, MODIS, AATSR and MERIS in the framework of the Cloud_cci project2017In: Earth System Science Data, ISSN 1866-3508, E-ISSN 1866-3516, Vol. 9, no 2, p. 881-904Article in journal (Refereed)
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  • 450. Stensgaard, A. -S
    et al.
    Booth, M.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Mccreesh, N.
    Combining a process-based and correlative approach to predict the impacts of climate change on schistosomiasis in eastern Africa2015In: Tropical medicine & international health, ISSN 1360-2276, E-ISSN 1365-3156, Vol. 20, p. 436-436Article in journal (Refereed)
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