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  • 351. Paprotny, D.
    et al.
    Morales-Napoles, O.
    Vousdoukas, M. I.
    Jonkman, S. N.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Accuracy of pan-European coastal flood mapping2019In: Journal of Flood Risk Management, ISSN 1753-318X, E-ISSN 1753-318X, Vol. 12, no 2, article id UNSP e12459Article in journal (Refereed)
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  • 352. Paquin, Jean-Philippe
    et al.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Sushama, Laxmi
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Causes and consequences of mid-21st-century rapid ice loss events simulated by the Rossby centre regional atmosphere-ocean model2013In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 65, article id 19110Article in journal (Refereed)
    Abstract [en]

    Recent observations and modelling studies suggest that the Arctic climate is undergoing important transition. One manifestation of this change is seen in the rapid sea-ice cover decrease as experienced in 2007 and 2012. Although most numerical climate models cannot adequately reproduce the recent changes, some models produce similar Rapid Ice Loss Events (RILEs) during the mid-21st-century. This study presents an analysis of four specific RILEs clustered around 2040 in three transient climate projections performed with the coupled Rossby Centre regional Atmosphere-Ocean model (RCAO). The analysis shows that long-term thinning causes increased vulnerability of the Arctic Ocean sea-ice cover. In the Atlantic sector, pre-conditioning (thinning of sea ice) combined with anomalous atmospheric and oceanic heat transport causes large ice loss, while in the Pacific sector of the Arctic Ocean sea-ice albedo feedback appears important, particularly along the retreating sea-ice margin. Although maximum sea-ice loss occurs in the autumn, response in surface air temperature occurs in early winter, caused by strong increase in ocean-atmosphere surface energy fluxes, mainly the turbulent fluxes. Synchronicity of the events around 2040 in the projections is caused by a strong large-scale atmospheric circulation anomaly at the Atlantic lateral boundary of the regional model. The limited impact on land is caused by vertical propagation of the surface heat anomaly rather than horizontal, caused by the absence of low-level temperature inversion over the ocean.

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  • 353. Paquin-Ricard, Danahe
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Vaillancourt, Paul A.
    Using ARM Observations to Evaluate Cloud and Clear-Sky Radiation Processes as Simulated by the Canadian Regional Climate Model GEM2010In: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 138, no 3, p. 818-838Article in journal (Refereed)
    Abstract [en]

    The total downwelling shortwave (SWID) and longwave (LWD) radiation and its components are assessed for the limited-area version of the Global Environmental Multiscale Model (GEM-LAM) against Atmospheric Radiation Measurements (ARM) at two sites: the southern Great Plains (SGP) and the North Slope of Alaska (NSA) for the 1998-2005 period. The model and observed SWD and LWD are evaluated as a function of the cloud fraction (CF), that is, for overcast and clear-sky conditions separately, to isolate and analyze different interactions between radiation and 1) atmospheric aerosols and water vapor and 2) cloud liquid water. Through analysis of the mean diurnal cycle and normalized frequency distributions of surface radiation fluxes, the primary radiation error in GEM-LAM is seen to be an excess in SWD in the middle of the day. The SWD bias results from a combination of underestimated CF and clouds, when present, possessing a too-high solar transmissivity, which is particularly the case for optically thin clouds. Concurrent with the SWD bias, a near-surface warm bias develops in GEM-LAM, particularly at the SGP site in the summer. The ultimate cause of this warm bias is difficult to uniquely determine because of the range of complex interactions between the surface, atmospheric, and radiation processes that are involved. Possible feedback loops influencing this warm bias are discussed. The near-surface warm bias is the primary cause of an excess clear-sky LWD. This excess is partially balanced with respect to the all-sky LWD by an underestimated CF, which causes a negative bias in simulated all-sky emissivity. It is shown that there is a strong interaction between all the components influencing the simulated surface radiation fluxes with frequent error compensation, emphasizing the need to evaluate the individual radiation components at high time frequency.

  • 354. Pereira, Susana Cardoso
    et al.
    Marta-Almeida, Martinho
    Carvalho, Ana
    SMHI, Research Department, Air quality.
    Rocha, Alfredo
    Extreme precipitation events under climate change in the Iberian Peninsula2019In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088Article in journal (Refereed)
    Abstract [en]

    Precipitation is one of the most important atmospheric variables to assess, particularly in the context of climate change. This study evaluates future changes in precipitation over the Iberian Peninsula (IP) under the RCP8.5 scenario. Changes are assessed for two future climate periods namely (2046-2065) and (2081-2100), relative to a recent reference climate (1986-2005). Here we introduce the concept of precipitation episodes (PEs) and estimate their statistical properties for the present climate and, their changes for future climate scenarios. PEs are defined by considering a full range of durations as well as intensities. This constitutes a novel approach to estimate changes with relevance, for example, for water resources applications. The climate simulations are performed with the Weather Research and Forecast (WRF) model. These are compared with an ensemble of other similar simulations from the Coordinated Downscaling Experiment initiative. This was done to evaluate the performance of the WRF model and also to estimate uncertainty of the derived future projections. Since models may present systematic errors, results from all simulations were previously bias corrected relative to observations using the same quantile mapping method. Under climate change, a great part of the region is expected to experience reduced annual precipitation of approximately 20-40% and reaching 80% in summer by the end of the XXI century. For the PEs, a large reduction in the average number of days and duration of all types of PEs is expected across all seasons and regions. The average intensity of episodes is projected to increase in winter and spring and decrease in summer. These results imply that climate change will likely influence precipitation and precipitation extremes in the 21st century, mostly in southern areas. These, together with projected warming may amplify desertification already taking place in the southern regions of the IP and cause stresses to water resources.

  • 355.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    En modell för beräkning av luftföroreningars spridning och deposition på mesoskala1980Report (Other academic)
    Abstract [sv]

    Mängden föroreningar, som förs till atmosfären, har under de senaste trettio åren kraftigt ökats. Deposition av dessa till marken leder till en rad biologiska effekter. Risker för skador på olika ekosystem genom deposition av tex tungmetaller och syra har därför alltmer börjat diskuteras som viktiga lokaliseringskriterier för fossileldade kraftverk och vissa större industrier. Depositionen av bly i omedelbar närhet av livligt trafikerade motorleder är ett annat exempel där negativa miljöeffekter befaras.

    Uppställandet av effektrelaterade utsläppskriterier medför ett behov av redskap för att kunna göra kvantitativa uppskattningar av förväntade depositioner i omgivningen av en källa. För kraftverk kan behovet av information om depositionsfördelningen, som underlag för lokaliseringsbeslut, röra ett område med flera hundra kilometers utsträckning.

    Vid studier av den lokala spridningen runt en punktkälla har under lång tid den gaussiska plymmodellen varit allmänt använd. Den utgör ett enkelt och i många fall mycket bra hjälpmedel, men har avsevärda begränsningar i de fall då depositionsprocesser och kemiska omvandlingar måste inkluderas i beräkningarna. I modeller baserade på diffusionsekvationen, där vissa antaganden om den turbulenta diffusiviteten görs (sk K-teori), finns möjlighet att på ett väsentligt mer realistiskt sätt inkludera processer som rör deposition och kemiska omvandlingar. Nackdelen är dock att den matematiska behandlingen blir mer komplicerad.

    Numeriska lösningar av diffusionsekvationen har använts av tex Bo in & Persson (1975) och Omstedt & Rodhe (1977). I båda fallen gällde tillämpningarna föroreningsspridning på storregional skala. Maul (1977) har presenterat en analytisk lösning, som tillämpats på föroreningsspridning på mesoskala. Svårigheterna vid tillämpningen av K-teorin är framförallt att bestämma riktiga värden på de ingångsparametrar som fordras. För analytiska lösningar finns dessutom matematiska hinder för godtyckliga vind- och diffusivitetsprofiler. Detta har resulterat i att beräkningar med K-modeller hittills huvudsakligen utförts för några enkla medelprofiler.

    Avsikten med föreliggande projekt har varit att utveckla en för praktiskt brukanvändbar spridningsmodell för studier av torr- och våtdepositionen av föroreningar på lokal- och mesoskala, där godtyckliga vind- och diffusivitetsprofiler kan användas. Dessa genereras med hjälp av en gränsskiktsmodell för olika vädersituationer.

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  • 356.
    Persson, Gunn
    SMHI, Professional Services.
    How much does it rain?2004In: Water research what´s next? / [ed] B. Johansson, Formas, Stockholm, Sweden,, 2004, p. 15-18Conference paper (Other academic)
  • 357.
    Persson, Gunn
    SMHI, Professional Services.
    Klimatförändringar i framtiden2006In: Poppel- sammanfattningar från ett seminarium vid Institutionen för Lövträdsodling, SLU , 2006, p. 66-67Conference paper (Other academic)
  • 358.
    Persson, Gunn
    et al.
    SMHI, Professional Services.
    Nylén, Linda
    SMHI, Professional Services.
    Berggreen-Clausen, Steve
    SMHI, Professional Services.
    Berg, Peter
    SMHI, Research Department, Climate research - Rossby Centre.
    Rayner, David
    SMHI.
    Sjökvist, Elin
    SMHI, Professional Services.
    Från utsläppsscenarier till lokal nederbörd och översvämningsrisker2016Report (Other academic)
    Abstract [en]

    In this report methods and results are presented from downscaling of about 40 climate scenarios to local time series for two drainage areas; River Torneå in northern Sweden and River Ätran in southern Sweden. Hydrological and hydraulic modelling has been made and flood maps have been produced for the cities Haparanda and Falkenberg. A study of future extreme precipitation is also presented. The work was performed within the project “Future rainfall and flooding in Sweden” financed by the Swedish Civil Contingencies Agency (MSB).

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    FULLTEXT01
  • 359.
    Persson, Gunn
    et al.
    SMHI, Professional Services.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Berg, Peter
    SMHI, Research Department, Climate research - Rossby Centre.
    Vägledning för användande av klimatscenarier2015Report (Other academic)
    Abstract [sv]

    SMHI fick i sitt regleringsbrev för år 2014 uppdraget att, i samråd med berörda myndigheter och andra aktörer, ta fram en vägledning för användandet av klimatscenarier. Enligt önskemål framtogs vägledningen som en webb-produkt på smhi.se, i anslutning till klimatscenarier. Materialet finns även samlat i denna rapport, såsom det lanserades hösten 2014. Eftersom materialet är uppbyggt för webb-presentation, där läsaren ska kunna gå in i kapitel utan att ha läst de tidigare, förekommer en del upprepningar. Klimatscenarier är beskrivningar av hur klimatet kan utvecklas i framtiden. Vägledningen ger stöd för att tolka och använda klimatscenarier, med dess möjligheter och begränsningar. Klimateffektstudier beskrivs översiktligt och med fokus på hydrologiska effektstudier. Några enkla steg för att komma igång med klimatanpassning presenteras också. I ordlistan förklaras de begrepp som används.

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  • 360.
    Persson, Gunn
    et al.
    SMHI, Professional Services.
    Wikberger, Christina
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Klimatanpassa nordiska städer med grön infrastruktur2018Report (Other academic)
    Abstract [sv]

    Förtätning av städer och pågående klimatförändring ökar behovet av anpassningsåtgärder. Grön infrastruktur och naturbaserade lösningar kan bidra till att skapa mer hälsosamma och långsiktigt hållbara städer. För att öka användningen av grön infrastruktur som en del i klimatanpassningen behöver vi förstå vilka kunskapsluckor och andra hinder som ligger i vägen för att grön infrastruktur ska användas i klimatanpassningsarbetet.

    SMHI har under år 2018 tillsammans med Stockholms stad drivit det av forskningsrådet Formas finansierade projektet ”Grön infrastruktur och klimat i nordiska städer: idag och i framtiden”. Sammanställningen av rapporter och workshops i projektet visar att det finns mycket kunskap och tillgängliga exempel på hur urbana gröna lösningar kan se ut. Det saknas dock svar på de kvantitativa effekterna av olika åtgärder avseende till exempel temperatur, luftkvalitet, påverkan på hälsa och sociala aspekter.

    De åtgärder som i dag görs i nordiska städer baseras huvudsakligen på behovet av att lösa dagvattenfrågor. Det finns få exempel på städer som använder grön infrastruktur och naturbaserade lösningar som klimatanpassningsåtgärder när det gäller värme. Samtidigt är aktörerna medvetna om övriga positiva effekter som tillkommer såsom trivsel, svalka och biologisk mångfald.

    Eftersom grön infrastruktur och naturbaserade lösningar är ganska nya åtgärder i klimatanpassningsarbetet så saknas oftast erfarenheter av långtidseffekter. Skötsel kan vara ett problem, trots bra anvisningar. Aktörerna pekar också på behovet av att engagera de boende kontinuerligt. Det tycks handla om att skapa en djupare förståelse för varför anläggningar ser ut som de gör och hur de ska skötas.

    Vid workshops och webbinarium efterfrågades vilka kunskapsluckor deltagarna såg. Ekonomi och kunskap om effekter lyftes fram tydligt i svaren. Dessutom önskades metoder för anläggning och drift, goda exempel, planeringsverktyg och underlag om temperatur och vatten.

    Ekonomi och kunskapsbrist ansågs som hinder för genomförande, vilket framkom vid workshops och webbinarium. Andra hinder som nämndes var politiska beslut, lagstiftning, avsaknad av riktlinjer, förtätning och konkurrens om mark liksom planerings- och samordningssvårigheter. En tröghet i att ändra traditionellt planerande och utförande pekades också ut som hinder. Många efterfrågar kunskap allmänt. Vår förhoppning är att denna rapport kan bidra till att inspirera och informera om var material finns. 

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  • 361. Pessacg, Natalia L.
    et al.
    Solman, Silvina A.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Sanchez, Enrique
    Marengo, Jose
    Li, Laurent
    Remedio, Armelle Reca C.
    da Rocha, Rosmeri P.
    Mourao, Caroline
    Jacob, Daniela
    The surface radiation budget over South America in a set of regional climate models from the CLARIS-LPB project2014In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 43, no 5-6, p. 1221-1239Article in journal (Refereed)
    Abstract [en]

    The performance of seven regional climate models in simulating the radiation and heat fluxes at the surface over South America (SA) is evaluated. Sources of uncertainty and errors are identified. All simulations have been performed in the context of the CLARIS-LPB Project for the period 1990-2008 and are compared with the GEWEX-SRB, CRU, and GLDAS2 dataset and NCEP-NOAA reanalysis. Results showed that most of the models overestimate the net surface short-wave radiation over tropical SA and La Plata Basin and underestimate it over oceanic regions. Errors in the short-wave radiation are mainly associated with uncertainties in the representation of surface albedo and cloud fraction. For the net surface long-wave radiation, model biases are diverse. However, the ensemble mean showed a good agreement with the GEWEX-SRB dataset due to the compensation of individual model biases. Errors in the net surface long-wave radiation can be explained, in a large proportion, by errors in cloud fraction. For some particular models, errors in temperature also contribute to errors in the net long-wave radiation. Analysis of the annual cycle of each component of the energy budget indicates that the RCMs reproduce generally well the main characteristics of the short- and long-wave radiations in terms of timing and amplitude. However, a large spread among models over tropical SA is apparent. The annual cycle of the sensible heat flux showed a strong overestimation in comparison with the reanalysis and GLDAS2 dataset. For the latent heat flux, strong differences between the reanalysis and GLDAS2 are calculated particularly over tropical SA.

  • 362. Peterson, T C
    et al.
    Easterling, D R
    Karl, T R
    Groisman, P
    Nicholls, N
    Plummer, N
    Torok, S
    Auer, I
    Boehm, R
    Gullett, D
    Vincent, L
    Heino, R
    Tuomenvirta, H
    Mestre, O
    Szentimrey, T
    Salinger, J
    Forland, E J
    Hanssen-Bauer, I
    Alexandersson, Hans
    SMHI.
    Jones, P
    Parker, D
    Homogeneity adjustments of in situ atmospheric climate data: A review1998In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 18, no 13, p. 1493-1517Article in journal (Refereed)
    Abstract [en]

    Long-term in situ observations are widely used in a variety of climate analyses. Unfortunately, most decade- to century-scale time series of atmospheric data have been adversely impacted by inhomogeneities caused by, for example, changes in instrumentation, station moves, changes in the local environment such as urbanization, or the introduction of different observing practices like a new formula for calculating mean daily temperature or different observation times. If these inhomogeneities are not accounted for properly, the results of climate analyses using these data on be erroneous. Over the last decade, many climatologists have put a great deal of effort into developing techniques to identify inhomogeneities and adjust climatic time series to compensate for the biases produced by the inhomogeneities. It is important for users of homogeneity-adjusted data to understand how the data were adjusted and what impacts these adjustments are likely to make on their analyses. And it is important for developers of homogeneity-adjusted data sets to compare readily the different techniques most commonly used today. Therefore, this paper reviews the methods and techniques developed for homogeneity adjustments and describes many different approaches and philosophies involved in adjusting in situ climate data. (C) 1998 Royal Meteorological Society.

  • 363. Pinto, Izidine
    et al.
    Lennard, Christopher
    Tadross, Mark
    Hewitson, Bruce
    Dosio, Alessandro
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Panitz, Hans-Juergen
    Shongwe, Mxolisi E.
    Evaluation and projections of extreme precipitation over southern Africa from two CORDEX models2016In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 135, no 3-4, p. 655-668Article in journal (Refereed)
  • 364. Pisinaras, Vassilios
    et al.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Gemitzi, Alexandra
    Conceptualizing and assessing the effects of installation and operation of photovoltaic power plants on major hydrologic budget constituents2014In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 493, p. 239-250Article in journal (Refereed)
    Abstract [en]

    This study addresses the effects of land use change from agricultural to photovoltaic parks (PVPs) on the hydrology of an area. Although many environmental effects have been identified and analyzed, only minor attention has been given to the hydrologic effects of the installation and operation of PVPs. The effects of current PVP installation and operation practices on major hydrologic budget constituents (surface runoff, evapotranspiration and percolation) were identified, conceptualized, quantified and simulated using SWAT model. Vosvozis river basin located in north Greece was selected as a test site. Additionally, long-term effects were simulated using dynamically downscaled climate projections by a Regional Climate Model (RCM) driven by 5 different General Circulation Models (GCMs) for the period 2011-2100. Results indicate that surface runoff and percolation potential are significantly increased at the local scale and have to be considered during PVP siting, especially when sensitive and protected ecosystems are involved. (C) 2014 Elsevier B.V. All rights reserved.

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

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

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

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

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

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

  • 368. Pryor, S. C.
    et al.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Influence of spatial resolution on regional climate model derived wind climates2012In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 117, article id D03117Article in journal (Refereed)
    Abstract [en]

    Wind speeds for a nominal height of 10 m and from the lowest model level (similar to 70 m above ground level) from the Rossby Center regional climate model (RCM) (RCA3) run at four resolutions between approximately 50 x 50 km and 6 x 6 km are analyzed to assess the effect of model resolution on wind climates. The influence of model resolution in this topographically simple subdomain of northern Europe is more profound in the wind extremes than in the central tendency. The domain-averaged mean wind speed at 10 m increases by 5% as the resolution increases from 50 to 6.25 km, while the 50 year return period wind speed and wind gust at this height increase by over 10% and 24%, respectively. Larger changes are observed in these wind speed metrics at the lowest model level as model resolution increases (similar to+10% in the mean and similar to+20% in the 50 year return period wind speed). These differences are of similar magnitude to the climate change signal in extreme wind events derived in prior research and may have implications for climate change risk and vulnerability analyses. Output from the lowest model level indicates some evidence for increased variability at synoptic and meso-alpha time scales with increased model resolution, but the effect is nonlinear. Furthermore, analysis of power spectra of grid cell average and tile fraction wind speeds at 10 m does not support the assertion that increased model resolution increases model skill at synoptic and meso-a time scales relative to in situ observations.

  • 369. Pryor, S.C.
    et al.
    Barthelmie, R.J.
    Schoof, J.T.
    Clausen, N.E.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Drews, M.
    Intense and extreme wind speeds over the Nordic countries2010Conference paper (Other academic)
  • 370. Pryor, S.C.
    et al.
    Barthelmie1, R.J.
    Claussen, N.E.
    Nielsen, N.M.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Drews, M.
    Climate change impacts on extreme wind speeds2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M, 2009, p. 271-272Conference paper (Other academic)
  • 371. Pucik, Tomas
    et al.
    Groenemeijer, Pieter
    Raedler, Anja T.
    Tijssen, Lars
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Prein, Andreas F.
    van Meijgaard, Erik
    Fealy, Rowan
    Jacob, Daniela
    Teichmann, Claas
    Future Changes in European Severe Convection Environments in a Regional Climate Model Ensemble2017In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 30, no 17, p. 6771-6794Article in journal (Refereed)
  • 372. Pulatov, Bakhtiyor
    et al.
    Jonsson, Anna Maria
    Wilcke, Renate
    SMHI, Research Department, Climate research - Rossby Centre.
    Linderson, Maj-Lena
    Hall, Karin
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Evaluation of the phenological synchrony between potato crop and Colorado potato beetle under future climate in Europe2016In: Agriculture, Ecosystems & Environment, ISSN 0167-8809, E-ISSN 1873-2305, Vol. 224, p. 39-49Article in journal (Refereed)
  • 373. Qian, Minwei
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Laprise, Rene
    Caya, Daniel
    The Influences of NAO and the Hudson Bay sea-ice on the climate of eastern Canada2008In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 31, no 2-3, p. 169-182Article in journal (Refereed)
  • 374. Radilovic, Slavko
    et al.
    Koracin, Darko
    Denamiel, Clea
    Belusic, Danijel
    SMHI, Research Department, Climate research - Rossby Centre.
    Guttler, Ivan
    Vilibic, Ivica
    Simulated and observed air temperature trends in the eastern Adriatic2020In: Atmospheric Science Letters, ISSN 1530-261X, E-ISSN 1530-261X, article id e951Article in journal (Refereed)
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  • 375. Rafael, S.
    et al.
    Martins, Helena
    SMHI, Research Department, Climate research - Rossby Centre.
    Marta-Almeida, M.
    Sa, E.
    Coelho, S.
    Rocha, A.
    Borrego, C.
    Lopes, M.
    Quantification and mapping of urban fluxes under climate change: Application of WRF-SUEWS model to Greater Porto area (Portugal)2017In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 155, p. 321-334Article in journal (Refereed)
  • 376. Rafael, S.
    et al.
    Martins, Helena
    SMHI, Research Department, Climate research - Rossby Centre.
    Sa, E.
    Carvalho, D.
    Borrego, C.
    Lopes, M.
    Influence of urban resilience measures in the magnitude and behaviour of energy fluxes in the city of Porto (Portugal) under a climate change scenario2016In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 566, p. 1500-1510Article in journal (Refereed)
  • 377. Rammig, A.
    et al.
    Jonsson, A. M.
    Hickler, T.
    Smith, B.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Sykes, M. T.
    Impacts of changing frost regimes on Swedish forests: Incorporating cold hardiness in a regional ecosystem model2010In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 221, no 2, p. 303-313Article in journal (Refereed)
    Abstract [en]

    Understanding the effects of climate change on boreal forests which hold about 7% of the global terrestrial biomass carbon is a major issue. An important mechanism in boreal tree species is acclimatization to seasonal variations in temperature (cold hardiness) to withstand low temperatures during winter. Temperature drops below the hardiness level may cause frost damage. Increased climate variability under global and regional warming might lead to more severe frost damage events, with consequences for tree individuals, populations and ecosystems. We assessed the potential future impacts of changing frost regimes on Norway spruce (Picea abies L. Karst.) in Sweden. A cold hardiness and frost damage model were incorporated within a dynamic ecosystem model, LPJ-GUESS. The frost tolerance of Norway spruce was calculated based on daily mean temperature fluctuations, corresponding to time and temperature dependent chemical reactions and cellular adjustments. The severity of frost damage was calculated as a growth-reducing factor when the minimum temperature was below the frost tolerance. The hardiness model was linked to the ecosystem model by reducing needle biomass and thereby growth according to the calculated severity of frost damage. A sensitivity analysis of the hardiness model revealed that the severity of frost events was significantly altered by variations in the hardening rate and dehardening rate during current climate conditions. The modelled occurrence and intensity of frost events was related to observed crown defoliation, indicating that 6-12% of the needle loss could be attributed to frost damage. When driving the combined ecosystem-hardiness model with future climate from a regional climate model (RCM), the results suggest a decreasing number and strength of extreme frost events particularly in northern Sweden and strongly increasing productivity for Norway spruce by the end of the 21st century as a result of longer growing seasons and increasing atmospheric CO(2) concentrations. However, according to the model, frost damage might decrease the potential productivity by as much as 25% early in the century. (C) 2009 Elsevier B.V. All rights reserved.

  • 378. Rana, Arun
    et al.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Kupiainen, Marco
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Kolax, Michael
    SMHI, Research Department, Climate research - Rossby Centre.
    Contrasting regional and global climate simulations over South Asia2020In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894Article in journal (Refereed)
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  • 379. Rasmus, S
    et al.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Lehning, M
    Estimating snow conditions in Finland in the late 21st century using the SNOWPACK model with regional climate scenario data as input2004In: ANNALS OF GLACIOLOGY, VOL 38 2004, 2004, p. 238-244Conference paper (Refereed)
    Abstract [en]

    An assessment of possible snow changes in a changing climate for Finland is presented. The snowpack structure model SNOWPACK (developed at the Swiss Federal Institute for Snow and Avalanche Research) was used for calculating snow conditions at six different locations in Finland for the decades 1980-89 and 2080-89. Regional climate model (RCAO) data from the Rossby Centre, Sweden, were used as input to the SNOWPACK model. Ten years from the RCAO control run and scenario run Were chosen, and the snow conditions for different snow zones were calculated for these winters. The snow-cover depth and duration decreased at all locations in the scenario run cases, and the snow-cover quality also changed between the control and scenario runs: grains were bigger, snow was warmer and denser, and the fraction of faceted snow decreased while the fraction of icy or melting snow increased, even in mid-winter. Finally, the variability between different global climate predictions was analyzed. Significant differences were found between different climate-model outputs. The inter-model variable is comparable to the interannual variability of a single model. The qualitative Conclusions from the scenario run do not critically depend oil the climate-model variability.

  • 380. Refsgaard, J. C.
    et al.
    Madsen, H.
    Andreassian, V.
    Arnbjerg-Nielsen, K.
    Davidson, T. A.
    Drews, M.
    Hamilton, D. P.
    Jeppesen, E.
    Kjellstrom, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Olesen, J. E.
    Sonnenborg, T. O.
    Trolle, D.
    Willems, P.
    Christensen, J. H.
    A framework for testing the ability of models to project climate change and its impacts2014In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 122, no 1-2, p. 271-282Article in journal (Refereed)
    Abstract [en]

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

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  • 381. Righi, Mattia
    et al.
    Andela, Bouwe
    Eyring, Veronika
    Lauer, Axel
    Predoi, Valeriu
    Schlund, Manuel
    Vegas-Regidor, Javier
    Bock, Lisa
    Broetz, Bjorn
    de Mora, Lee
    Diblen, Faruk
    Dreyer, Laura
    Drost, Niels
    Earnshaw, Paul
    Hassler, Birgit
    Koldunov, Nikolay
    Little, Bill
    Tomas, Saskia Loosveldt
    Zimmermann, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Earth System Model Evaluation Tool (ESMValTool) v2.0-technical overview2020In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 13, no 3, p. 1179-1199Article in journal (Refereed)
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  • 382. Roth, Matthias
    et al.
    Jansson, Christer
    SMHI, Research Department, Climate research - Rossby Centre.
    Velasco, Erik
    Multi-year energy balance and carbon dioxide fluxes over a residential neighbourhood in a tropical city2017In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 37, no 5, p. 2679-2698Article in journal (Refereed)
  • 383. Ruete, Alejandro
    et al.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Stenseth, Nils Chr.
    Snall, Tord
    Disentangling effects of uncertainties on population projections: climate change impact on an epixylic bryophyte2012In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 279, no 1740, p. 3098-3105Article in journal (Refereed)
    Abstract [en]

    Assessment of future ecosystem risks should account for the relevant uncertainty sources. This means accounting for the joint effects of climate variables and using modelling techniques that allow proper treatment of uncertainties. We investigate the influence of three of the IPCC's scenarios of greenhouse gas emissions (special report on emission scenarios (SRES)) on projections of the future abundance of a bryophyte model species. We also compare the relative importance of uncertainty sources on the population projections. The whole chain global climate model (GCM)-regional climate model-population dynamics model is addressed. The uncertainty depends on both natural-and model-related sources, in particular on GCM uncertainty. Ignoring the uncertainties gives an unwarranted impression of confidence in the results. The most likely population development of the bryophyte Buxbaumia viridis towards the end of this century is negative: even with a low-emission scenario, there is more than a 65 per cent risk for the population to be halved. The conclusion of a population decline is valid for all SRES scenarios investigated. Uncertainties are no longer an obstacle, but a mandatory aspect to include in the viability analysis of populations.

  • 384.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Methods for statistical downscaling of GCM simulations1997Report (Other academic)
    Abstract [en]

    General Circulation Models (GCMs) are used to study the change of climate due to increases in greenhouse gases in the atmosphere. As GCMs operate on !arge spatial scales, and, furthermore, as the GCM-simulated temporal resolution corresponds to monthly averages at best, the usefulness of GCM data in impact studies and other applications is limited. The present-day free troposphere is modeled relatively well by the coarse GCMs, whereas local or even regional characteristics in surface or near-surface climate variables, their variability and the likelihood of extreme events cannot be obtained directly from GCMs. The same is likely true in the case of climate change experiments with GCMs. The results from GCMs can be superimposed on climatological local­ scale time series or interpreted in some other way in order to address the needs of impact studies. This is known as "downscaling" of GCM simulations. In this survey, five different downscaling methods are introduced. These are the conventional, the statistical, the stochastic, the dynamical and the composite methods. Only the statistical and, to a lesser extent, the stochastic approaches are discussed in detail. This survey is a planning document in the SWECLIM program.

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  • 385.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Recent Development of a Regional Air/Land Surface/Sea/Ice Coupling Modeling System, “the RCAO Experience”2004In: Fourth Study Conference on BALTEX: Conference Proceedings / [ed] Hans-Jörg Isemer, 2004, p. 148-149Conference paper (Other academic)
  • 386.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Reflections on the uncertainty in climate scenarios.2005In: Uncertainty and Active Risk Management and Forestry / [ed] Kristina Blennow, Sveriges lantbruksuniversitet. Institutionen för sydsvensk skogsvetenskap , 2005, p. 22-24Conference paper (Other academic)
  • 387.
    Rummukainen, Markku
    SMHI, Core Services.
    State-of-the-art with regional climate models2010In: Wiley Interdisciplinary Reviews: Climate Change, ISSN 1757-7780, E-ISSN 1757-7799, Vol. 1, no 1, p. 82-96Article, review/survey (Refereed)
    Abstract [en]

    Regional climate models are used by a large number of groups, for more or less all regions of the world. Regional climate models are complementary to global climate models. A typical use of regional climate models is to add further detail to global climate analyses or simulations, or to study climate processes in more detail than global models allow. The relationship between global and regional climate models is much akin to that of global and regional weather forecasting models. Over the past 20 years, the development of regional climate models has led to increased resolution, longer model runs, and steps towards regional climate system models. During recent years, community efforts have started to emerge in earnest, which can be expected to further advance the state-of-the-art in regional climate modeling. Applications of regional climate models span both the past and possible future climates, facilitating climate impact studies, information and support to climate policy, and adaptation. (C) 2010 John Wiley & Sons, Ltd. WIREs Clim Change 2010 1 82-96

  • 388.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Persson, Gunn
    SMHI, Professional Services.
    Rodhe, J
    Tjernstrom, M
    The Swedish Regional Climate Modelling Programme, SWECLIM: A review2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, no 4-5, p. 176-182Article, review/survey (Refereed)
    Abstract [en]

    The Swedish Regional Climate Modelling Programme, SWECLIM, was a 6.5-year national research network for regional climate modeling, regional climate change projections and hydrological impact assessment and information to a wide range of stakeholders. Most of the program activities focussed on the regional climate system of Northern Europe. This led to the establishment of an advanced, coupled atmosphere-ocean-hydrology regional climate model system, a suite of regional climate change projections and progress on relevant data and process studies. These were, in turn, used for information and educational purposes, as a starting point for impact analyses on different societal sectors and provided contributions also to international climate research.

  • 389.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Graham, Phil
    SMHI, Professional Services.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    PRUDENCE-related regional climate modeling at the SMHI/Rossby Centre2002In: PRUDENCE kick-off meeting / [ed] Jens Hesselbjerg Christensen, Danish Climate Centre DMI, Ministry of Transport , 2002, p. 40-41Conference paper (Other academic)
  • 390.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Hewitt, Chris
    Jacob, Daniela
    The ENSEMBLES and the BALTEX Projects2007Conference paper (Other academic)
  • 391.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Isaksen, I S A
    Rognerud, B
    Stordal, F
    A global model tool for three-dimensional multiyear stratospheric chemistry simulations: Model description and first results1999In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 104, no D21, p. 26437-26456Article in journal (Refereed)
    Abstract [en]

    The paper presents a new global modeling tool, Stratospheric Chemical Transport Model 2. It has been developed for effective three-dimensional multiyear stratospheric chemistry studies, featuring an extensive chemistry scheme, heterogeneous processing on sulfate aerosols, and some polar stratospheric cloud processes. The transport algorithm maintains sub-grid-scale distributions and connects vertically the stratospheric layers, even in a coarse vertical grid. The model has been integrated for 49 months, recycling 1 year of precalculated transport from a middle atmosphere general circulation model. One year of daily National Centers for Environmental Prediction global analyses are used as temperatures. Diurnal cycles of photolysis rates are recalculated every 7 days to give interaction with ozone changes. The model is able to describe most of the geographical and seasonal ozone variability and the meridional distributions of ozone, reactive nitrogen, chlorine, and bromine. Stratospheric diurnal cycles for nitrogen, hydrogen, chlorine, and bromine species are captured in detail. The upper stratosphere ozone deficiency, typical to models, is large. Its sensitivity to different ways of tuning are explored. Midlatitude, rather than polar, wintertime processes have so far been the focus in this model tool. The present transport and grid resolution are not suited for realistic simulations at high latitudes. As there is only a limited inclusion of polar stratospheric cloud (PSC) microphysics, chemical processing in the cold polar lower stratosphere also cannot be well simulated. For example, the Antarctic ozone hole is not simulated, but the modeled chemistry should be suitable for warm Arctic winters when type II PSCs and particle sedimentation do not occur.

  • 392.
    Rummukainen, Markku
    et al.
    SMHI, Core Services.
    Rockel, Burkhardt
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Jens Hesselbjerg
    Reckermann, Marcus
    Twenty-First-Century Challenges in Regional Climate Modeling2015In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 96, no 8, p. ES135-ES138Article in journal (Refereed)
  • 393.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Ruosteenoja, K
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Impacts of Climate Change on Renewable Energy Sources: Their role in the Nordic energy system: A comprehensive report resulting from a Nordic Energy Research project2007Report (Other academic)
  • 394.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Bjorge, D
    Christensen, J H
    Christensen, O B
    Iversen, T
    Jylha, K
    Olafsson, H
    Tuomenvirta, H
    Regional climate scenarios for use in Nordic water resources studies2003In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 34, no 5, p. 399-412Article in journal (Refereed)
    Abstract [en]

    According to global climate projections, a substantial global climate change will occur during the next decades, under the assumption of continuous anthropogenic climate forcing. Global models, although fundamental in simulating the response of the climate system to anthropogenic forcing are typically geographically too coarse to well represent many regional or local features. In the Nordic region, climate studies are conducted in each of the Nordic countries to prepare regional climate projections with more detail than in global ones. Results so far indicate larger temperature changes in the Nordic region than in the global mean, regional increases and decreases in net precipitation, longer growing season, shorter snow season etc. These in turn affect runoff, snowpack, groundwater, soil frost and moisture, and thus hydropower production potential, flooding risks etc. Regional climate models do not yet fully incorporate hydrology. Water resources studies are carried out off-line using hydrological models. This requires archived meteorological output from climate models. This paper discusses Nordic regional climate scenarios for use in regional water resources studies. Potential end-users of water resources scenarios are the hydropower industry, dam safety instances and planners of other lasting infrastructure exposed to precipitation, river flows and flooding.

  • 395.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Bringfelt, Björn
    SMHI, Research Department, Climate research - Rossby Centre.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    Willen, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    A regional climate model for northern Europe: model description and results from the downscaling of two GCM control simulations2001In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 17, no 5-6, p. 339-359Article in journal (Refereed)
    Abstract [en]

    This work presents a regional climate model, the Rossby Centre regional Atmospheric model(RCA1), recently developed from the High Resolution Limited Area Model (HIRLAM). The changes in the HIRLAM parametrizations, necessary for climate-length integrations, are described. A regional Baltic Sea ocean model and a modeling system for the Nordic inland lake systems have been coupled with RCA1. The coupled system has been used to downscale 10-year time slices from two different general circulation model (GCM) simulations to provide high-resolution regional interpretation of large-scale modeling. A selection of the results from the control runs, i.e. the present-day climate simulations, are presented: large-scale free atmospheric fields, the surface temperature and precipitation results and results for the on-line simulated regional ocean and lake surface climates. The regional model modifies the surface climate description compared to the GCM simulations, but it is also substantially affected by the biases in the GCM simulations. The regional model also improves the representation of the regional ocean and the inland lakes, compared to the GCM results.

  • 396.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    SWECLIM participants, SWECLIM participants
    The Swedish regional climate modeling program 1996-2003: Final report2003Report (Other academic)
    Abstract [en]

    The Swedish Regional Climate Modeling Program (SWECLIM) was a 6.5-year national research effort with the aim of providing the Swedish society with more detailed regional climate scenarios than those available from international global climate mode! simulations. SWECLIM built up a new scientific niche in Sweden, namely that of climate modeling, provided users with regionally detailed climate scenarios, expert advice and synthesis of climate changescience. Regional climate modeling was a major activity, supported with studies of climate processes as well as on observed data on the Baltic Sea, regional hydrology and meteorology. The major impact study part was on hydrological modeling, to elaborate the potential impact of regional-scale climate change on hydropower, dam safety and water resources in general. Other types of impact studies were not performed by SWECLIM itself, but means were provided for outside experts to pursue such knowledge. This fmihered the general understanding of climate change and created new insights into planning processes, especially in Sweden, but also on theNordic, European and global arenas.Examples of practical users of the results were experts and decision-makers within national, regional and local administration, organizations, businesses, politicians, as well as media and the general public. These Swedish cfforts on climate science also contributed to international research and assessment networks, and to the quest for better knowledge base to act on in dealing with the climate problem.This repor! provides the final reporting of the SWECLIM-program, building on earlier reports and complements the results published in scientific journals, as reports, presented in meetings and provided to the general public. The focus here is on the work undertaken <luring program phase 2, lasting from July 2000 to June 2003.

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  • 397.
    Rutgersson, Anna
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bumke, K
    Clemens, M
    Foltescu, Valentin
    SMHI.
    Lindau, R
    Michelson, Daniel
    SMHI, Core Services.
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    Precipitation estimates over the Baltic Sea: Present state of the art2001In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 32, no 4-5, p. 285-314Article in journal (Refereed)
    Abstract [en]

    Precipitation is one of the main components in the water balance, and probably the component determined with the greatest uncertainties. In the present paper we focus on precipitation (mainly rain) over the Baltic Sea as a part of the BAL-TEX project to examine the present state of the art concerning different precipitation estimates over that area. Several methods are used, with the focus on 1) interpolation of available synoptic stations; 2) a mesoscale analysis system including synoptic, automatic, and climate stations, as well as weather radar and an atmospheric model; and 3) measurements performed on ships. The investigated time scales are monthly and yearly and also some long-term considerations are discussed. The comparison shows that the differences between most of the estimates, when averaged over an extended period and a larger area, are in the order of 10-20%, which is in the same range as the correction of the synoptic gauge measurements due to wind and evaporation losses. In all data sets using gauge data it is important to include corrections for high winds. To improve the structure of precipitation over sea more focus is to be put on the use of radar data and combinations of radar data and other data. Interpolation methods that do not consider orographic effects must treat areas with large horizontal precipitation gradients with care. Due to the large variability in precipitation in time and space, it is important to use long time periods for climate estimates of precipitation. Ship measurements are a valuable contribution to precipitation information over sea, especially for seasonal and annual time scales.

  • 398.
    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.

  • 399.
    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.

  • 400.
    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.

567891011 351 - 400 of 523
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