Change search
Refine search result
678910 401 - 450 of 493
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 401. 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.

  • 402.
    Schöld, Sofie
    et al.
    SMHI, Core Services.
    Ivarsson, Cajsa-Lisa
    SMHI, Professional Services.
    Nerheim, Signild
    SMHI, Professional Services.
    Södling, Johan
    SMHI, Professional Services.
    Beräkning av högsta vattenstånd längs Sveriges kust2018Report (Other academic)
    Abstract [sv]

    I rapporten redovisas hur en metod framtagits för att kunna skatta de allra högsta havsvattenstånd som kan uppträda vid de mätstationer för havsvattenstånd som finns längs Sveriges kust. Metoden är generell och principerna kan därför tillämpas på mätdataserier från olika platser. För att kunna tillämpa metoden måste dock mätdataserien ha en viss minimilängd och tidsupplösning. Resultaten som tas fram är empiriska, vilket betyder att de baseras på tillgängliga mätdata.

    I analysen delades data upp i två delar; det genomsnittliga vattenståndet före en högvattenhändelse och nettohöjningen under en högvattenhändelse. Dessa delar benämns havsnivå före storm respektive nettohöjning, i enlighet med:

    stormflod = havsnivå före storm + nettohöjning

    Nivån på stormfloden är det högsta uppmätta havsvattenståndet under respektive högvattenhändelse. I analysen har även högvattenhändelser som inte förknippas med stormar inkluderats. Många av de högsta stormfloderna har inträffat när havsnivån före storm är förhöjd jämfört med medelvattenståndet, framförallt i stora delar av Östersjön. I analysen ingår samtliga högvattenhändelser från vilka det finns tillgänglig mätdata, även sådana som startat från ett lågt utgångsläge.

    I analysen indelades mätstationerna i olika kustområden och samvariationen mellan mätstationerna undersöktes. För varje enskild station, där havsvattenstånd observeras, har högsta havsnivå före storm och högsta nettohöjning framtagits. Den högsta havsnivån före storm som uppmätts inom kustområdet bedömdes gälla för alla mätstationer inom området. Det högsta beräknade havsvattenståndet definierades som kustområdets högsta havsnivå före storm plus mätstationens högsta nettohöjning.

    Tidvatteneffekten har inte beaktats särskilt, utan är i viss mån inkluderad i nettohöjningen. Denna förenkling beskrivs närmare i Schöld m fl. (2017).

    Analysen visade att:

    • samvariationen inom kustområden är mycket hög för vanligt förekommande vattenstånd.
    • högvattenhändelser förekommer oftare i vissa kustområden.
    • de högsta vattenstånden kan variera mycket, även mellan stationer inom samma kustområde.
    • havsnivån före storm är en mer betydande stormflodskomponent i Östersjön och mindre betydande i Skagerrak-Kattegatt.
    • havsnivån före storm behöver identifieras så att den inte är påverkad av själva stormhändelsen.
    • det är lämpligt att uppdatera det högsta beräknade havsvattenståndet regelbundet,särskilt efter att nya rekordhöga stormfloder inträffat.

    Vi valde att definiera havsnivån före storm som ett medelvärde över sju dygn, 48 timmar före stormflodens maximum. Metodiken avser nivåer ovanpå ett gällande medelvattenstånd. Framtida förändringar av medelvattenståndet orsakade av den globala klimatförändringen behandlas inte i denna rapport. Tillämpningen av metoden i ett framtida klimat beskrivs i Nerheim m fl. (2017).

  • 403.
    Segersson, David
    SMHI, Research Department, Air quality.
    Numerical Quantification of Driving Rain on Buildings2003Report (Other academic)
    Abstract [en]

    Rain, which is given a horizontal velocity component by the influence of wind, is termed winddriven or driving rain. Driving rain is one of the main sources to the amount of moisture a building is exposed to, and thereby contributes to the processes deteriorating the building envelope. Examples of damages to the building envelope that the onslaught of driving rain directly or indirectly can contribute to are: cracks caused by the freezing of water absorbed in the facade, mould or rot, corrosion of concrete reinforcements and soiling patterns. Knowledge about the exposure of a building to driving rain is needed in order to minimise the deteriorating processes, and thus contributes to ensure a satisfactory performance of the building design.

    This work is meant as an introduction to the field of numerical quantification of driving rain on buildings. Focus is set on three-dimensional simulation of the wind flow and raindrop trajectories using CFD (Computational Fluid Dynamics). lnterest is also paid to some specific properties of rainfall, such as drop size distributions and drag forces on raindrops. The study includes a detailed description of a method to calculate the driving rain distribution on a building, as well as application of the method to a rectangular facade. A qualitative evaluation of the results indicates that the method can be used to calculate the mean distribution of driving rain on simple geometries with sufficient accuracy.

  • 404. 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.

  • 405.
    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.

  • 406.
    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.

  • 407. 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.

  • 408. 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)
  • 409.
    Sjökvist, Elin
    et al.
    SMHI, Professional Services.
    Abdoush, Diala
    SMHI, Core Services.
    Sommaren 2018 - en glimt av framtiden?2019Report (Other academic)
    Abstract [en]

    The weather in the summer of 2018 was extreme compared to what Sweden experienced during the 20th century. In some places, heat records were broken, and the combination of exceptional warm conditions with a deficit in precipitation caused a severe drought followed by forest fires and crop failure. Knowledge about impacts from climate change leads to the question: Will conditions like those in the summer of 2018 be average at the end of this century? This report compares different statistical measures from the summer of 2018 with by SMHI previously published climate scenarios.

  • 410. 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.

  • 411. 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)
  • 412. 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.

  • 413. 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.

  • 414. 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.

  • 415. 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.

  • 416. 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)
  • 417. 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.

  • 418. 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.

  • 419. 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)
  • 420.
    Stensen, Katarina
    et al.
    SMHI, Core Services.
    Tengdelius Brunell, Johanna
    SMHI, Professional Services.
    Sjökvist, Elin
    SMHI, Professional Services.
    Andersson, Elinor
    SMHI, Core Services.
    Eklund, Anna
    SMHI, Core Services.
    Vattentemperaturer och is i Mälaren Beräkningar för dagens och framtidens klimatförhållanden2017Report (Other academic)
    Abstract [sv]

    Denna rapport presenterar hur vattentemperatur och is beräknas förändras i Mälaren tillmitten av seklet och fram till 2100 på grund av den globala uppvärmningen.Beräkningarna är gjorda med en sjömodell där Mälaren är uppdelad i två bassänger. Dekallas västra Mälaren och östra Mälaren.De tydligaste förändringarna i Mälaren i ett framtida klimat beräknas bli högrevattentemperaturer både på ytan och på botten samt kortare period med is. Iberäkningarna har två framtidsscenarier använts, vilka baseras på mängden växthusgaser iatmosfären. I det högre scenariot, vilket motsvarar fortsatta utsläpp med dagensutsläppsnivåer, ökar vattentemperaturen mer jämfört med scenariot där utsläppen avväxthusgaser är begränsade.Sammanfattning av resultaten för klimatscenarierna: Den årliga perioden som Mälaren är täckt med is beräknas minska med enmånad till två månader mot slutet av seklet. Ytvattnets medeltemperatur beräknas öka 1,5 till 2,5 grader för bådabassängerna. Förändringen är ungefär lika stor under hela året. Bottenvattnets medeltemperatur väntas öka mellan 1 till 2 grader i den grundarevästra bassängen och 0,5 till 1,5 grader i den djupare östra bassängen.Förändringen är ungefär lika stor under hela året. Maxtemperaturen ökar något mer än medeltemperaturen för både ytvatten ochbottenvatten. Den period som ytvattnets dygnsmedeltemperatur är över 20 grader, ökar medcirka en månad upp till en och en halv månad.Medeltemperaturen och maxtemperaturen för dagens klimat är beräknad utifråntidsperioden 1997-2015 och utifrån 2032-2050 och 2080-2098 för ett framtida klimat.Maxtemperaturen är det högsta värdet som beräknas uppnås under perioden.

  • 421.
    Stensen, Katarina
    et al.
    SMHI, Core Services.
    Tengdelius Brunell, Johanna
    SMHI, Professional Services.
    Sjökvist, Elin
    SMHI, Professional Services.
    Andersson, Elinor
    SMHI, Core Services.
    Eklund, Anna
    SMHI, Core Services.
    Vattentemperaturer och is i Mälaren Beräkningar för dagens och framtidens klimatförhållanden2018Report (Other academic)
  • 422. 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)
  • 423. Stensgaard, Anna-Sofie
    et al.
    Booth, Mark
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    McCreesh, Nicky
    Combining process-based and correlative models improves predictions of climate change effects on Schistosoma mansoni transmission in eastern Africa2016In: GEOSPATIAL HEALTH, ISSN 1827-1987, Vol. 11, p. 94-101Article in journal (Refereed)
  • 424. Sterl, Andreas
    et al.
    Bintanja, Richard
    Brodeau, Laurent
    Gleeson, Emily
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Schmith, Torben
    Semmler, Tido
    Severijns, Camiel
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Yang, Shuting
    A look at the ocean in the EC-Earth climate model2012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 39, no 11, p. 2631-2657Article in journal (Refereed)
    Abstract [en]

    EC-Earth is a newly developed global climate system model. Its core components are the Integrated Forecast System (IFS) of the European Centre for Medium Range Weather Forecasts (ECMWF) as the atmosphere component and the Nucleus for European Modelling of the Ocean (NEMO) developed by Institute Pierre Simon Laplace (IPSL) as the ocean component. Both components are used with a horizontal resolution of roughly one degree. In this paper we describe the performance of NEMO in the coupled system by comparing model output with ocean observations. We concentrate on the surface ocean and mass transports. It appears that in general the model has a cold and fresh bias, but a much too warm Southern Ocean. While sea ice concentration and extent have realistic values, the ice tends to be too thick along the Siberian coast. Transports through important straits have realistic values, but generally are at the lower end of the range of observational estimates. Exceptions are very narrow straits (Gibraltar, Bering) which are too wide due to the limited resolution. Consequently the modelled transports through them are too high. The strength of the Atlantic meridional overturning circulation is also at the lower end of observational estimates. The interannual variability of key variables and correlations between them are realistic in size and pattern. This is especially true for the variability of surface temperature in the tropical Pacific (El Nio). Overall the ocean component of EC-Earth performs well and helps making EC-Earth a reliable climate model.

  • 425. Stiller, Joerg
    et al.
    Fladrich, Uwe
    SMHI, Research Department, Climate research - Rossby Centre.
    FACTORIZATION TECHNIQUES FOR NODAL SPECTRAL ELEMENTS IN CURVED DOMAINS2008In: SIAM Journal on Scientific Computing, ISSN 1064-8275, E-ISSN 1095-7197, Vol. 30, no 5, p. 2286-2301Article in journal (Refereed)
  • 426.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt (, J.
    KTH, Department of Mechanics.
    High-resolution regional climate model simulations for a 50-year period under Last Glacial Maximum conditions.2009Conference paper (Other academic)
  • 427.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, J
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Modelling last glacial maximum climate variability with a high resolution regional climate model2008In: Abstracts of the contributions of the EGU General Assembly 2008, 2008, article id EGU2008-A-03244Conference paper (Other academic)
  • 428.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, Jenny
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Smith, Benjamin
    High-resolution regional simulation of last glacial maximum climate in Europe2011In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 63, no 1, p. 107-125Article in journal (Refereed)
  • 429.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Brandefelt, Jenny
    KTH, Dept. of Mech.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Smith, Benjamin
    Lund Universitt, Dept. of Physical Geography and Ecosystems Analysis.
    Simulating cold palaeo climate conditions in Europe with a regional climate model2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M., 2009, p. 280-281Conference paper (Other academic)
  • 430.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellstrom, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Poska, A.
    Wagner, S.
    Gaillard, M. -J
    Trondman, A. -K
    Mauri, A.
    Davis, B. A. S.
    Kaplan, J. O.
    Birks, H. J. B.
    Bjune, A. E.
    Fyfe, R.
    Giesecke, T.
    Kalnina, L.
    Kangur, M.
    van der Knaap, W. O.
    Kokfelt, U.
    Kunes, P.
    Latalowa, M.
    Marquer, L.
    Mazier, F.
    Nielsen, A. B.
    Smith, B.
    Seppa, H.
    Sugita, S.
    Regional climate model simulations for Europe at 6 and 0.2 k BP: sensitivity to changes in anthropogenic deforestation2014In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 10, no 2, p. 661-680Article in journal (Refereed)
    Abstract [en]

    This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, similar to 6 and similar to 0.2 k BP in Europe. We apply We apply the Rossby Centre regional climate model RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three alternative descriptions of the past vegetation: (i) potential natural vegetation (V) simulated by the dynamic vegetation model LPJ-GUESS, (ii) potential vegetation with anthropogenic land use (deforestation) from the HYDE3.1 (History Database of the Global Environment) scenario (V + H3.1), and (iii) potential vegetation with anthropogenic land use from the KK10 scenario (V + KK10). The climate model results show that the simulated effects of deforestation depend on both local/regional climate and vegetation characteristics. At similar to 6 k BP the extent of simulated deforestation in Europe is generally small, but there are areas where deforestation is large enough to produce significant differences in summer temperatures of 0.5-1 degrees C. At similar to 0.2 k BP, extensive deforestation, particularly according to the KK10 model, leads to significant temperature differences in large parts of Europe in both winter and summer. In winter, deforestation leads to lower temperatures because of the differences in albedo between forested and unforested areas, particularly in the snow-covered regions. In summer, deforestation leads to higher temperatures in central and eastern Europe because evapotranspiration from unforested areas is lower than from forests. Summer evaporation is already limited in the southernmost parts of Europe under potential vegetation conditions and, therefore, cannot become much lower. Accordingly, the albedo effect dominates in southern Europe also in summer, which implies that deforestation causes a decrease in temperatures. Differences in summer temperature due to deforestation range from -1 degrees C in south-western Europe to +1 degrees C in eastern Europe. The choice of anthropogenic land-cover scenario has a significant influence on the simulated climate, but uncertainties in palaeoclimate proxy data for the two time periods do not allow for a definitive discrimination among climate model results.

  • 431.
    Strandberg, Gustav
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Climate Impacts from Afforestation and Deforestation in Europe2019In: Earth Interactions, ISSN 1087-3562, E-ISSN 1087-3562, Vol. 23, no 1, article id 1Article in journal (Refereed)
  • 432.
    Taesler, Roger
    SMHI, Research Department.
    CLIMATE AND BUILDING ENERGY MANAGEMENT1991In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 16, no 1-2, p. 599-608Article in journal (Refereed)
    Abstract [en]

    Indoor climate control is a major energy demand everywhere. Design and operation of buildings and HVAC systems crucially depend on climate data and real-time meteorological conditions. Energy-efficient buildings also contribute to reduce air pollution and climate change in urban areas as well as regionally and globally. However, the effects of climate and weather on building energy management are still largely overlooked in practice. A main reason for this is the lack of tools for translating meteorological conditions into energy requirements. The combined impact of temperature, solar irradiation, wind and humidity on the energy balance of a building depends on the building itself, i.e., its design, orientation, HVAC system, mode of operation, maintenance, etc. The paper discusses different approaches to model this complex interplay and associated problems at the design as well as in the operation stages. Recent developments in Sweden are reported, including applications to urban planning, building design and real-time operation of buildings and energy systems. The impact of solar irradiation and wind, in addition to that of temperature, is demonstrated. Further, the paper discusses the significance of local site condition versus building characteristics.

  • 433.
    Taesler, Roger
    SMHI, Research Department.
    THE BIOCLIMATE IN TEMPERATE AND NORTHERN CITIES1991In: International journal of biometeorology, ISSN 0020-7128, E-ISSN 1432-1254, Vol. 35, no 3, p. 161-168Article in journal (Refereed)
    Abstract [en]

    Climate is a basic component of the human environment. Developments in building design and indoor climate control have contributed greatly to improving human health and comfort. By contrast, the possibilities for improving urban climatic conditions by deliberate planning have been poorly exploited. The structure and processes of the urban atmosphere in extratropical regions are briefly described. The impact of certain selected urban climates on human health is summarized. The need for relevant bioclimatological "design tools" for applications in urban planning is stressed, followed by a brief review of some recent work on human thermal comfort. It is argued that the modification of present day comfort criteria to reflect human adaptation to climate may be important for further improvements of indoor climate. as well as for deducing the emissions of air pollutants and greenhouse gases.

  • 434. Tamoffo, Alain T.
    et al.
    Moufouma-Okia, Wilfran
    Dosio, Alessandro
    James, Rachel
    Pokam, Wilfried M.
    Vondou, Derbetini A.
    Fotso-Nguemo, Thierry C.
    Guenang, Guy Merlin
    Kamsu-Tamo, Pierre H.
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Longandjo, Georges-Noel
    Lennard, Christopher J.
    Bell, Jean-Pierre
    Takong, Roland R.
    Haensler, Andreas
    Tchotchou, Lucie A. Djiotang
    Nouayou, Robert
    Process-oriented assessment of RCA4 regional climate model projections over the Congo Basin under 1.5. C and 2. C global warming levels: influence of regional moisture fluxes2019In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 53, no 3-4, p. 1911-1935Article in journal (Refereed)
  • 435. Tangang, Fredolin
    et al.
    Santisirisomboon, Jerasorn
    Juneng, Liew
    Salimun, Ester
    Chung, Jingxiang
    Supari, Supari
    Cruz, Faye
    Ngai, Sheau Tieh
    Ngo-Duc, Thanh
    Singhruck, Patama
    Narisma, Gemma
    Santisirisomboon, Jaruthat
    Wongsaree, Waranyu
    Promjirapawat, Kamphol
    Sukamongkol, Yod
    Srisawadwong, Ratchanan
    Setsirichok, Damrongrit
    Phan-Van, Tan
    Aldrian, Edvin
    Gunawan, Dodo
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Yang, Hongwei
    Projected future changes in mean precipitation over Thailand based on multi-model regional climate simulations of CORDEX Southeast Asia2019In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 39, no 14, p. 5413-5436Article in journal (Refereed)
  • 436. Taylor, Christopher M.
    et al.
    Belusic, Danijel
    SMHI, Research Department, Climate research - Rossby Centre.
    Guichard, Francoise
    Arker, Douglas J. P.
    Vischel, Theo
    Bock, Olivier
    Harris, Phil P.
    Janicot, Serge
    Klein, Cornelia
    Panthou, Geremy
    Frequency of extreme Sahelian storms tripled since 1982 in satellite observations2017In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 544, no 7651, p. 475-+Article in journal (Refereed)
  • 437. Taylor, Christopher M.
    et al.
    Birch, Cathryn E.
    Parker, Douglas J.
    Dixon, Nick
    Guichard, Francoise
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Lister, Grenville M. S.
    Modeling soil moisture-precipitation feedback in the Sahel: Importance of spatial scale versus convective parameterization2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 23, p. 6213-6218Article in journal (Refereed)
    Abstract [en]

    Feedback between soil moisture and precipitation influence climate variability in semiarid regions. However, serious concerns exist about the ability of coarse-scale global atmospheric models to depict one key aspect of the feedback loop, namely the sensitivity of daytime convection to soil moisture. Here we compare regional simulations using a single model, run at different spatial resolutions, and with convective parameterizations switched on or off against Sahelian observations. Convection-permitting simulations at 4 and 12 km capture the observed relationships between soil moisture and convective triggering, emphasizing the importance of surface-driven mesoscale dynamics. However, with the inclusion of the convection scheme at 12 km, the behavior of the model fundamentally alters, switching from negative to positive feedback. Similar positive feedback is found in 9 out of 10 Regional Climate Models run at 50 km. These results raise questions about the accuracy of the feedback in regional models based on current convective parameterizations.

  • 438. Teixeira, J. C.
    et al.
    Fallmann, J.
    Carvalho, Ana
    SMHI, Research Department, Air quality.
    Rocha, A.
    Surface to boundary layer coupling in the urban area of Lisbon comparing different urban canopy models in WRF2019In: Urban Climate, ISSN 2212-0955, E-ISSN 2212-0955, Vol. 28, article id UNSP 100454Article in journal (Refereed)
  • 439.
    Thomas, Manu Anna
    et al.
    SMHI, Research Department, Air quality.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Kokkola, H.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Integration of prognostic aerosol-cloud interactions in a chemistry transport model coupled offline to a regional climate model2015In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 8, no 6, p. 1885-1898Article in journal (Refereed)
    Abstract [en]

    To reduce uncertainties and hence to obtain a better estimate of aerosol (direct and indirect) radiative forcing, next generation climate models aim for a tighter coupling between chemistry transport models and regional climate models and a better representation of aerosol-cloud interactions. In this study, this coupling is done by first forcing the Rossby Center regional climate model (RCA4) with ERA-Interim lateral boundaries and sea surface temperature (SST) using the standard cloud droplet number concentration (CDNC) formulation (hereafter, referred to as the 'stand-alone RCA4 version' or 'CTRL' simulation). In the stand-alone RCA4 version, CDNCs are constants distinguishing only between land and ocean surface. The meteorology from this simulation is then used to drive the chemistry transport model, Multiple-scale Atmospheric Transport and Chemistry (MATCH), which is coupled online with the aerosol dynamics model, Sectional Aerosol module for Large Scale Applications (SALSA). CDNC fields obtained from MATCH-SALSA are then fed back into a new RCA4 simulation. In this new simulation (referred to as 'MOD' simulation), all parameters remain the same as in the first run except for the CDNCs provided by MATCH-SALSA. Simulations are carried out with this model setup for the period 2005-2012 over Europe, and the differences in cloud microphysical properties and radiative fluxes as a result of local CDNC changes and possible model responses are analysed. Our study shows substantial improvements in cloud microphysical properties with the input of the MATCH-SALSA derived 3-D CDNCs compared to the stand-alone RCA4 version. This model setup improves the spatial, seasonal and vertical distribution of CDNCs with a higher concentration observed over central Europe during boreal summer (JJA) and over eastern Europe and Russia during winter (DJF). Realistic cloud droplet radii (CD radii) values have been simulated with the maxima reaching 13 mu m, whereas in the stand-alone version the values reached only 5 mu m. A substantial improvement in the distribution of the cloud liquid-water paths (CLWP) was observed when compared to the satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) for the boreal summer months. The median and standard deviation values from the 'MOD' simulation are closer to observations than those obtained using the stand-alone RCA4 version. These changes resulted in a significant decrease in the total annual mean net fluxes at the top of the atmosphere (TOA) by -5 W m(-2) over the domain selected in the study. The TOA net fluxes from the 'MOD' simulation show a better agreement with the retrievals from the Clouds and the Earth's Radiant Energy System (CERES) instrument. The aerosol indirect effects are estimated in the 'MOD' simulation in comparison to the pre-industrial aerosol emissions (1900). Our simulations estimated the domain averaged annual mean total radiative forcing of -0.64 W m(-2) with a larger contribution from the first indirect aerosol effect (-0.57 W m(-2)) than from the second indirect aerosol effect (-0.14 W m(-2)).

  • 440.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Roberts, Malcolm
    Roberts, Christopher
    Lohmann, Katja
    A statistical and process-oriented evaluation of cloud radiative effects in high-resolution global models2019In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 12, no 4, p. 1679-1702Article in journal (Refereed)
  • 441.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    L'Ecuyer, Tristan
    Wang, Shiyu
    SMHI, Research Department, Climate research - Rossby Centre.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Snowfall distribution and its response to the Arctic Oscillation: an evaluation of HighResMIP models in the Arctic using CPR/CloudSat observations2019In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 12, no 8, p. 3759-3772Article in journal (Refereed)
  • 442.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Tjernstrom, Michael
    Ekman, Annica M. L.
    The Relation Between Aerosol Vertical Distribution and Temperature Inversions in the Arctic in Winter and Spring2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 5, p. 2836-2845Article in journal (Refereed)
  • 443.
    Thompson, Thomas
    et al.
    SMHI.
    Udin, Ingemar
    SMHI, Core Services.
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    Sea surface temperatures in waters surrounding Sweden1974Report (Other academic)
    Abstract [en]

    One of the sub-projects within the sea ice research programme carried out at SMHI deals with the thermodynamics of the sea and the ice. In these studies the sea surface temperature plays a fundamental r ole. During the latest years considerable efforts have been made in order to obtain more temperature observations, in particular from the open sea. Various vessels have been equipped with new instruments, the collection of observations improved, the sea surface temperature distribution analyzed every second day and all information stored in digital form.

    The instruments are discribed and their specifications given in the report. Various observational methods are compared and examples of sea surface temperature analyses for the period July 1973 - July 1974  illustrating yearly variations, tendency to circulation patterns, coastal effects, up-welling etc. are given.

  • 444. Tjernstrom, M
    et al.
    Zagar, M
    Svensson, G
    Cassano, J J
    Pfeifer, S
    Rinke, A
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Dethloff, K
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Semmler, T
    Shaw, M
    Modelling the arctic boundary layer: An evaluation of six arcmip regional-scale models using data from the Sheba project2005In: Boundary-layer Meteorology, ISSN 0006-8314, E-ISSN 1573-1472, Vol. 117, no 2, p. 337-381Article in journal (Refereed)
    Abstract [en]

    A primary climate change signal in the central Arctic is the melting of sea ice. This is dependent on the interplay between the atmosphere and the sea ice, which is critically dependent on the exchange of momentum, heat and moisture at the surface. In assessing the realism of climate change scenarios it is vital to know the quality by which these exchanges are modelled in climate simulations. Six state-of-the-art regional-climate models are run for one year in the western Arctic, on a common domain that encompasses the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment ice-drift track. Surface variables, surface fluxes and the vertical structure of the lower troposphere are evaluated using data from the SHEBA experiment. All the models are driven by the same lateral boundary conditions, sea-ice fraction and sea and sea-ice surface temperatures. Surface pressure, near-surface air temperature, specific humidity and wind speed agree well with observations, with a falling degree of accuracy in that order. Wind speeds have systematic biases in some models, by as much as a few metres per second. The surface radiation fluxes are also surprisingly accurate, given the complexity of the problem. The turbulent momentum flux is acceptable, on average, in most models, but the turbulent heat fluxes are, however, mostly unreliable. Their correlation with observed fluxes is, in principle, insignificant, and they accumulate over a year to values an order of magnitude larger than observed. Typical instantaneous errors are easily of the same order of magnitude as the observed net atmospheric heat flux. In the light of the sensitivity of the atmosphere-ice interaction to errors in these fluxes, the ice-melt in climate change scenarios must be viewed with considerable caution.

  • 445. Tjernström, M.
    et al.
    Zagar, M.
    Svensson, G.
    Dethloff, K.
    Rinke, A.
    Cassano, J.
    Pfeifer, S.
    Semmler, T.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    The Arctic boundary-layer in six different RCM compared to SHEBA observations (ARCMIP).2005In: Extended abstracts of a WMO/WCRP-sponsored Regional-Scale Climate Modelling Workshop [Elektronisk resurs] : high-resolution climate modelling : assessment, added value and applications, Lund, Sweden, 29 March-2 April 2004 / [ed] Lars Bärring & René Laprise, Lund: Department of Physical Geography & Ecosystems Analysis, Lund University , 2005, p. 44-45Conference paper (Other academic)
  • 446. Tobin, Isabelle
    et al.
    Jerez, Sonia
    Vautard, Robert
    Thais, Francoise
    van Meijgaard, Erik
    Prein, Andreas
    Deque, Michel
    Kotlarski, Sven
    Maule, Cathrine Fox
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Noel, Thomas
    Teichmann, Claas
    Climate change impacts on the power generation potential of a European mid-century wind farms scenario2016In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 11, no 3, article id 034013Article in journal (Refereed)
    Abstract [en]

    Wind energy resource is subject to changes in climate. To investigate the impacts of climate change on future European wind power generation potential, we analyze a multi-model ensemble of the most recent EURO-CORDEX regional climate simulations at the 12 km grid resolution. We developed a mid-century wind power plant scenario to focus the impact assessment on relevant locations for future wind power industry. We found that, under two greenhouse gas concentration scenarios, changes in the annual energy yield of the future European wind farms fleet as a whole will remain within +/- 5% across the 21st century. At country to local scales, wind farm yields will undergo changes up to 15% in magnitude, according to the large majority of models, but smaller than 5% in magnitude for most regions and models. The southern fleets such as the Iberian and Italian fleets are likely to be the most affected. With regard to variability, changes are essentially small or poorly significant from subdaily to interannual time scales.

  • 447. Toledano, C.
    et al.
    Cachorro, V. E.
    Gausa, M.
    Stebel, K.
    Aaltonen, V.
    Berjon, A.
    Ortiz de Galisteo, J. P.
    de Frutos, A. M.
    Bennouna, Y.
    Blindheim, S.
    Myhre, C. L.
    Zibordi, G.
    Wehrli, C.
    Kratzer, S.
    Håkansson, Bertil
    SMHI, Research Department, Oceanography.
    Carlund, Thomas
    SMHI, Core Services.
    de Leeuw, G.
    Herber, A.
    Torres, B.
    Overview of sun photometer measurements of aerosol properties in Scandinavia and Svalbard2012In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 52, p. 18-28Article in journal (Refereed)
    Abstract [en]

    An overview on the data of columnar aerosol properties measured in Northern Europe is provided. Apart from the necessary data gathered in the Arctic, the knowledge of the aerosol loading in nearby areas (e.g. sub-Arctic) is of maximum interest to achieve a correct analysis of the Arctic aerosols and transport patterns. This work evaluates data from operational sites with sun photometer measurements belonging either to national or international networks (AERONET, GAW-PFR) and programs conducted in Scandinavia and Svalbard. We enumerate a list of sites, measurement type and periods together with observed aerosol properties. An evaluation and analysis of aerosol data was carried out with a review of previous results as well. Aerosol optical depth (AOD) and Angstrom exponent (AE) are the current parameters with sufficient long-term records for a first evaluation of aerosol properties. AOD (500 nm) ranges from 0.08 to 0.10 in Arctic and sub-Arctic sites (Ny-Alesund: 0.09; Andenes: 0.10; Sodankyla: 0.08), and it is somewhat higher in more populated areas in Southern Scandinavia (AOD about 0.10-0.12 at 500 nm). On the Norwegian coast, aerosols show larger mean size (AE = 1.2 at Andenes) than in Finland, with continental climate (AE = 1.5 at Sodankyla). Columnar particle size distributions and related parameters derived from inversion of sun/sky radiances were also investigated. This work makes special emphasis in the joint and collaborative effort of the various groups from different countries involved in this study. Part of the measurements presented here were involved in the IPY projects Polar-AOD and POLARCAT. (C) 2011 Elsevier Ltd. All rights reserved.

  • 448. Tourigny, Etienne
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    An analysis of regional climate model performance over the tropical Americas. Part I: simulating seasonal variability of precipitation associated with ENSO forcing2009In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 61, no 3, p. 323-342Article in journal (Refereed)
    Abstract [en]

    Sea surface temperature (SST) anomalies associated with El Nino/Southern Oscillation (ENSO) constitute a major source of predictability in the tropics. We evaluate the ability of a regional climate model (the Rossby Centre Atmospheric Model; RCA) to downscale SST and large-scale atmospheric anomalies associated with ENSO. RCA is configured over the tropical east Pacific and tropical Americas and runs for the period 1979-2005, using European Centre for Medium-Range Weather Forecasts (ECMWF) lateral and surface boundary conditions. We study the ability of RCA to represent regional patterns of precipitation, with respect to both the climatology and interannual variability associated with ENSO. The latter is achieved by grouping the simulations into El Nino and La Nina composites and studying the delayed response of precipitation to SST forcing in four regions of Central and South America. In this paper, we concentrate on seasonal mean timescales. We find that RCA accurately simulates the main features of the precipitation climatology over the four regions and also reproduces the majority of the documented regional responses to ENSO forcing. Furthermore, the model captures the variability in precipitation anomalies between different ENSO events. The model exhibits a wet bias over the northern Amazon and slightly overestimates the magnitude of ENSO anomalies over Central America.

  • 449. Tourigny, Etienne
    et al.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    An analysis of regional climate model performance over the tropical Americas. Part II: simulating subseasonal variability of precipitation associated with ENSO forcing2009In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 61, no 3, p. 343-356Article in journal (Refereed)
    Abstract [en]

    The El Nino/Southern Oscillation (ENSO) constitutes a major source of potential predictability in the tropics. The majority of past seasonal prediction studies have concentrated on precipitation anomalies at the seasonal mean timescale. However, fields such as agriculture and water resource management require higher time frequency forecasts of precipitation variability. Regional climate models (RCMs), with their increased resolution, may offer one means of improving general circulation model forecasts of higher time frequency precipitation variability. Part I of this study evaluated the ability of the Rossby Centre regional atmospheric model (RCA), forced by analysed boundary conditions, to simulate seasonal mean precipitation anomalies over the tropical Americas associated with ENSO variability. In this paper the same integrations are analysed, with the focus now on precipitation anomalies at subseasonal (pentad) timescales. RCA simulates the climatological annual cycle of pentad-mean precipitation intensity quite accurately. The timing of the rainy season (onset, demise and length) is well simulated, with biases generally of less than 2 weeks. Changes in the timing and duration of the rainy season, associated with ENSO forcing, are also well captured. Finally, pentad-mean rainfall intensity distributions are simulated quite accurately, as are shifts in these distributions associated with ENSO forcing.

  • 450. Tuomenvirta, H
    et al.
    Alexandersson, Hans
    SMHI.
    Drebs, A
    Frich, P
    Nordli, P O
    Trends in Nordic and Arctic temperature extremes and ranges2000In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 13, no 5, p. 977-990Article in journal (Refereed)
    Abstract [en]

    The national meteorological institutes in the Nordic countries have produced a comprehensive dataset of climatic extreme temperatures (monthly mean daily maximum and minimum, and monthly absolute highest and lowest temperatures) comprising stations from Fenno-Scandia, the Nordic Seas, and Greenland. Mean maximum and minimum temperatures show statistically significant negative trends in western coastal Greenland during the period 1950-95, while over the Nordic Seas and Fenno-Scandia the trends are generally positive. The diurnal temperature range (DTR) is decreasing significantly throughout the study area and is unrelated to regional temperature trends, which show both warming and cooling. The opposite temperature trends between western coastal Greenland and Fenno-Scandia since the 1950s are in accordance with a strengthening of the North Atlantic Oscillation (NAO). However, the simple NAO index fails to explain the decrease of DTR. In Fenno-Scandia, the reliable long-term mean maximum and minimum temperatures show cooling in winter and warming in spring and summer during the period 1910-95. Simultaneously, DTR has been decreasing in all seasons except winter. Most of the decrease has occurred since the 1940s. Atmospheric circulation indices defined by zonal and meridional sea level pressure differences, along with sea level pressure and cloud cover anomalies were used to build a multiple linear regression model for the Fenno-Scandian DTR. During the period 1910-95 the model explains from 53% (winter) to 80% (summer) of the variation in DTR and reproduces the statistically significant decreasing trend on annual level. Cloud cover is the dominant predictor, while circulation provides substantial improvement in explanation.

678910 401 - 450 of 493
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.8
|