Change search
Refine search result
38394041424344 2001 - 2050 of 2199
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.
  • 2001.
    Thompson, Thomas
    et al.
    SMHI.
    Ulander, Lars
    SMHI.
    Håkansson, Bertil
    SMHI, Research Department, Oceanography.
    Brusmark, Bertil
    SMHI.
    Carlström, Anders
    SMHI.
    Gustavsson, Anders
    SMHI.
    BEERS -92: Final edition1992Report (Other academic)
  • 2002.
    Tiderman, Karin
    SMHI, Core Services.
    Sänkta och torrlagda sjöar: Svenskt Vattenarkiv1995Report (Other academic)
  • 2003. Tilmes, S
    et al.
    Brandt, J
    Flatoy, F
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Flemming, J
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Christensen, J H
    Frohn, L M
    Hov, O
    Jacobsen, I
    Reimer, E
    Stern, R
    Zimmermann, J
    Comparison of five eulerian air pollution forecasting systems for the summer of 1999 using the German ozone monitoring data2002In: Journal of Atmospheric Chemistry, ISSN 0167-7764, E-ISSN 1573-0662, Vol. 42, no 1, p. 91-121Article in journal (Refereed)
    Abstract [en]

    Eulerian state-of-the-art air pollution forecasting systems on the European scale are operated routinely by several countries in Europe. DWD and FUB, both Germany, NERI, Denmark, NILU, Norway, and SMHI, Sweden, operate some of these systems. To apply such modeling systems, e.g. for regulatory purposes according to new EU directives, an evaluation and comparison of the model systems is fundamental in order to assess their reliability. One step in this direction is presented in this study: The model forecasts from all five systems have been compared to measurements of ground level ozone in Germany. The outstanding point in this investigation is the availability of a huge amount of data - from forecasts by the different model systems and from observations. This allows for a thorough interpretation of the findings and assures the significance of the observed features. Data from more than 300 measurement stations for a 5-month period (May-September 1999) of the German monitoring networks have been used in this comparison. Different spatial and temporal statistical parameters were applied in the evaluation. Generally, it was found that the most comprehensive models gave the best results. However, the less comprehensive and computational cheaper models also produced good results. The extensive comparison made it possible to point out weak points in the different models and to describe the individual model behavior for a full summer period in a climatological sense. The comparison also gave valuable information for an assessment of individual measurement stations and complete monitoring networks in terms of the representativeness of the observation data.

  • 2004. Tiselius, Peter
    et al.
    Belgrano, Andrea
    Andersson, Lars
    SMHI, Core Services.
    Lindahl, Odd
    Contribution to the Themed Section: Scaling from individual Plankton to marine ecosystems Primary productivity in a coastal ecosystem: a trophic perspective on a long-term time series2016In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 38, no 4, p. 1092-1102Article in journal (Refereed)
  • 2005. Tjernstrom, M.
    et al.
    Birch, C. E.
    Brooks, I. M.
    Shupe, M. D.
    Persson, P. O. G.
    Sedlar, Joseph
    SMHI, Research Department, Atmospheric remote sensing.
    Mauritsen, T.
    Leck, C.
    Paatero, J.
    Szczodrak, M.
    Wheeler, C. R.
    Meteorological conditions in the central Arctic summer during the Arctic Summer Cloud Ocean Study (ASCOS)2012In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, no 15, p. 6863-6889Article in journal (Refereed)
    Abstract [en]

    Understanding the rapidly changing climate in the Arctic is limited by a lack of understanding of underlying strong feedback mechanisms that are specific to the Arctic. Progress in this field can only be obtained by process-level observations; this is the motivation for intensive ice-breaker-based campaigns such as the Arctic Summer Cloud-Ocean Study (ASCOS), described here. However, detailed field observations also have to be put in the context of the larger-scale meteorology, and short field campaigns have to be analysed within the context of the underlying climate state and temporal anomalies from this. To aid in the analysis of other parameters or processes observed during this campaign, this paper provides an overview of the synoptic-scale meteorology and its climatic anomaly during the ASCOS field deployment. It also provides a statistical analysis of key features during the campaign, such as key meteorological variables, the vertical structure of the lower troposphere and clouds, and energy fluxes at the surface. In order to assess the representativity of the ASCOS results, we also compare these features to similar observations obtained during three earlier summer experiments in the Arctic Ocean: the AOE-96, SHEBA and AOE-2001 expeditions. We find that these expeditions share many key features of the summertime lower troposphere. Taking ASCOS and the previous expeditions together, a common picture emerges with a large amount of low-level cloud in a well-mixed shallow boundary layer, capped by a weak to moderately strong inversion where moisture, and sometimes also cloud top, penetrate into the lower parts of the inversion. Much of the boundary-layer mixing is due to cloud-top cooling and subsequent buoyant overturning of the cloud. The cloud layer may, or may not, be connected with surface processes depending on the depths of the cloud and surface-based boundary layers and on the relative strengths of surface-shear and cloud-generated turbulence. The latter also implies a connection between the cloud layer and the free troposphere through entrainment at cloud top.

  • 2006. Tjernstrom, M.
    et al.
    Leck, C.
    Birch, C. E.
    Bottenheim, J. W.
    Brooks, B. J.
    Brooks, I. M.
    Backlin, L.
    Chang, Y. -W
    de Leeuw, G.
    Di Liberto, L.
    de la Rosa, S.
    Granath, E.
    Graus, M.
    Hansel, A.
    Heintzenberg, J.
    Held, A.
    Hind, A.
    Johnston, P.
    Knulst, J.
    Martin, M.
    Matrai, P. A.
    Mauritsen, T.
    Mueller, M.
    Norris, S. J.
    Orellana, M. V.
    Orsini, D. A.
    Paatero, J.
    Persson, P. O. G.
    Gao, Q.
    Rauschenberg, C.
    Ristovski, Z.
    Sedlar, Joseph
    SMHI, Research Department, Atmospheric remote sensing.
    Shupe, M. D.
    Sierau, B.
    Sirevaag, A.
    Sjogren, S.
    Stetzer, O.
    Swietlicki, E.
    Szczodrak, M.
    Vaattovaara, P.
    Wahlberg, N.
    Westberg, M.
    Wheeler, C. R.
    The Arctic Summer Cloud Ocean Study (ASCOS): overview and experimental design2014In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 14, no 6, p. 2823-2869Article in journal (Refereed)
    Abstract [en]

    The climate in the Arctic is changing faster than anywhere else on earth. Poorly understood feedback processes relating to Arctic clouds and aerosol-cloud interactions contribute to a poor understanding of the present changes in the Arctic climate system, and also to a large spread in projections of future climate in the Arctic. The problem is exacerbated by the paucity of research-quality observations in the central Arctic. Improved formulations in climate models require such observations, which can only come from measurements in situ in this difficult-to-reach region with logistically demanding environmental conditions. The Arctic Summer Cloud Ocean Study (ASCOS) was the most extensive central Arctic Ocean expedition with an atmospheric focus during the International Polar Year (IPY) 2007-2008. ASCOS focused on the study of the formation and life cycle of low-level Arctic clouds. ASCOS departed from Longyearbyen on Svalbard on 2 August and returned on 9 September 2008. In transit into and out of the pack ice, four short research stations were undertaken in the Fram Strait: two in open water and two in the marginal ice zone. After traversing the pack ice northward, an ice camp was set up on 12 August at 87 degrees 21' N, 01 degrees 29' W and remained in operation through 1 September, drifting with the ice. During this time, extensive measurements were taken of atmospheric gas and particle chemistry and physics, mesoscale and boundary-layer meteorology, marine biology and chemistry, and upper ocean physics. ASCOS provides a unique interdisciplinary data set for development and testing of new hypotheses on cloud processes, their interactions with the sea ice and ocean and associated physical, chemical, and biological processes and interactions. For example, the first-ever quantitative observation of bubbles in Arctic leads, combined with the unique discovery of marine organic material, polymer gels with an origin in the ocean, inside cloud droplets suggests the possibility of primary marine organically derived cloud condensation nuclei in Arctic stratocumulus clouds. Direct observations of surface fluxes of aerosols could, however, not explain observed variability in aerosol concentrations, and the balance between local and remote aerosols sources remains open. Lack of cloud condensation nuclei (CCN) was at times a controlling factor in low-level cloud formation, and hence for the impact of clouds on the surface energy budget. ASCOS provided detailed measurements of the surface energy balance from late summer melt into the initial autumn freeze-up, and documented the effects of clouds and storms on the surface energy balance during this transition. In addition to such process-level studies, the unique, independent ASCOS data set can and is being used for validation of satellite retrievals, operational models, and reanalysis data sets.

  • 2007. 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.

  • 2008. Tjernström, M
    et al.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Rodhe, J.
    SMHI.
    Persson, Gunn
    SMHI, Professional Services.
    Klimatmodellering och klimatscenarier ur SWECLIMs perspektiv2003Report (Other academic)
  • 2009. 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)
  • 2010. 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.

  • 2011. 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.

  • 2012. Tonderski, K S
    et al.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Pers, Charlotta
    SMHI, Research Department, Hydrology.
    Modeling the impact of potential wetlands on phosphorus retention in a Swedish catchment2005In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, no 7, p. 544-551Article in journal (Refereed)
    Abstract [en]

    In southern Sweden, wetlands are constructed to remove nitrogen (N) in agricultural catchments. The possible effects of such wetlands on riverine phosphorus (P) were also estimated using input-output data from three well-monitored wetlands. This was done to formulate a simple model for removal of P that is dependent on inflow characteristics. Next, the N- and P-reducing effects of wetlands were modeled on a catchment scale (1900 km 2) using the HBV-NP model and various assumptions about the wetland area and location. All three wetlands functioned as sinks for total P (tot-P) and for total suspended solids (TSS) with a removal of 10% to 31% and 28% to 50%, respectively. Mean P-removal rates of 17-49 kg ha(-1) yr(-1) were well simulated with the model. Catchment scale simulations indicated that wetlands were more efficient (in percentage of load) as traps for P than for N and that this may motivate the construction of wetlands for P removal far upstream from the catchment outlet.

  • 2013. Tonderski, Karin
    et al.
    Andersson, Lotta
    SMHI, Research Department, Hydrology.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    St Cyr, Rasmus
    Schoenberg, Ronny
    Taubald, Heinrich
    Assessing the use of delta O-18 in phosphate as a tracer for catchment phosphorus sources2017In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 607, p. 1-10Article in journal (Refereed)
  • 2014. 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.

  • 2015. 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.

  • 2016.
    Trolez, Matthieu
    et al.
    SMHI.
    Karlsson, Karl-Göran
    SMHI, Research Department, Atmospheric remote sensing.
    Johnston, Sheldon
    SMHI, Research Department, Climate research - Rossby Centre.
    Albert, Peter
    SMHI.
    The impact of varying NWP background information on CM-SAF cloud products: Visiting Scientist Report Climate Monitoring SAF (CM-SAF)2008Report (Other academic)
    Abstract [en]

    The purpose of this study was to quantify the impact of using ancillary data from Numerical Weather Prediction (NWP) models in the derivation of cloud parameters from satellite data in the Climate Monitoring Satellite Application Facility (CM-SAF) project. In particular, the sensitivity to the NWP-analysed surface temperature parameter was studied.A one-year dataset of satellite images over the Scandinavian region from the Advanced Very High Resolution Radiometer (AVHRR) on the polar orbiting NOAA satellites was studied. Cloud products were generated by use of the Polar Platform System (PPS) cloud software and the sensitivity to perturbations of the NWP-analysed surface temperature was investigated. In addition, a study on the importance of the chosen NWP model was also included. Results based on three different NWP models (ECMWF, HIRLAM and GME) were analysed.It was concluded that the NWP model influence on the results appears to be small. An interchange of NWP model analysis input data to the PPS cloud processing method did only lead to marginal changes of the resulting CM-SAF cloud products. Thus, the current CM-SAF cloud algorithmsproduce robust results that are not heavily dependent on NWP model background information. Nevertheless, the study demonstrated a natural high sensitivity to the NWP-analysed surface skin temperature. This parameter is crucial for the a priori determination of the thresholds used for the infrared cloud tests of the PPS method. It was shown that a perturbation of the surface skin temperature of one K generally resulted in a change of cloud cover of about 0.5-1 % in absolute cloud amount units. However, if perturbations were in the range 5-10 K the change in cloud cover increased to values between 1 to 2 % per degree, especially for positive perturbations. Important here is that a positive surface temperature perturbation always leads to an increase in the resulting cloud amounts and vice versa.

  • 2017.
    Trolez, Matthieu
    et al.
    SMHI.
    Tetzlaff, Anke
    SMHI, Research Department, Atmospheric remote sensing.
    Karlsson, Karl-Göran
    SMHI, Research Department, Atmospheric remote sensing.
    CM-SAF Validating the Cloud Top Height product using LIDAR data2005Report (Other academic)
  • 2018. 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.

  • 2019. Tuomi, Laura
    et al.
    Kanarik, Hedi
    Bjorkqvist, Jan-Victor
    Marjamaa, Riikka
    Vainio, Jouni
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    Höglund, Anders
    SMHI, Research Department, Oceanography.
    Kahma, Kimmo K.
    Impact of Ice Data Quality and Treatment on Wave Hindcast Statistics in Seasonally Ice-Covered Seas2019In: Frontiers in Earth Science, ISSN 2296-6463, Vol. 7, article id UNSP 166Article in journal (Refereed)
  • 2020. Turner, David R.
    et al.
    Edman, Moa
    SMHI, Research Department, Oceanography.
    Gallego-Urrea, Julian Alberto
    Claremar, Bjorn
    Hassellov, Ida-Maja
    Omstedt, Anders
    Rutgersson, Anna
    The potential future contribution of shipping to acidification of the Baltic Sea2018In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 47, no 3, p. 368-378Article in journal (Refereed)
  • 2021. Turpin, O C
    et al.
    Caves, R G
    Ferguson, R I
    Johansson, Barbro
    SMHI, Professional Services.
    Verification of simulated snow cover in an Arctic basin using satellite-derived snow-cover maps2000In: ANNALS OF GLACIOLOGY, VOL 31, 2000, 2000, p. 391-396Conference paper (Refereed)
    Abstract [en]

    Time series of Earth observation (EO) data (Landsat Thematic Mapper (TM), U.S. National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA AVHRR) and European Remote-sensing Satellite synthetic-aperture radar (ERS SAR)) were obtained for a 2250 km(2) mountainous basin in northern Sweden to validate snow-cover area (SCA) estimates produced by a conceptual model (HBV) during three melt. seasons. SCA depletion curves derived for each image type, and coincident images, reveal that the SCA estimate varies with the sensor. Discrepancies betweenc TM and AVHRR appear to be an effect of spatial resolution. However, differences between TM and SAR are not simply related. Since more AVHRR than TM data were available, a TM-equivalent SCA was derived from AVHRR by relating TM SCA to AVHRR channel 1 reflectance. The TM-equivalent SCA was used to test SCA simulated by HBV for the 1992 melt season. Although the modelled and TM-equivalent SCA were in reasonable agreement, the modelled SCA declined faster than the TM-equivalent SCA. Partial recalibration of model parameters controlling snowpack accumulation improved the match between the modelled and EO-derived SCA decline. The recalibrated parameters were verified using SCA maps generated for the 1996 and 1998 melt seasons. The adjusted parameter sets had little effect on the Nash-Sutcliffe R-2 runoff fit but improved the volume fit in all three years.

  • 2022. Tyson, P D
    et al.
    Garstang, M
    Swap, R
    Kållberg, Per
    SMHI, Research Department, Meteorology.
    Edwards, M
    An air transport climatology for subtropical southern Africa1996In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 16, no 3, p. 265-291Article in journal (Refereed)
    Abstract [en]

    An air transport climatology is derived for subtropical southern Africa (Africa south of 15 degrees S) by classifying daily synoptic situations into predominant circulation types. The annual variation of these provides the basis for determining month-by-month transport. Percentage zonal transport in easterly and westerly directions, levels of transport, and times of transit are derived from forward trajectory analyses using European Centre for Medium-range Weather Forecasts (ECMWF) data for a 7-year period. It is shown that semi-permanent subtropical continental anticyclones, transient mid-latitude ridging anticyclones and midlatitude westerly disturbances produce major transport into the south-western Indian Ocean in the Natal plume. Only quasistationary tropical easterly waves result in appreciable transport into the tropical South Atlantic Ocean in the Angolan plume. Total transport is a function of circulation type and frequency, as well as plume dimensions. Transport in continental highs follows an annual cycle reaching peak values in excess of 70 per cent in winter. That in easterly waves also exhibits an annual cycle, but one peaking in summer, when up to 55 per cent transport may occur in north-western regions. Transport in ridging highs and westerly perturbations is much less and occurs throughout the year, with a slight tendency to peak in spring. Recirculation of air is shown to be considerable when anticyclonic conditions prevail. Monthly, seasonal, and annual mass fluxes over and out of southern Africa are determined from transport fields, frequency of occurrence of circulation types and from measurements of aerosol concentrations. An annual mass flux of aerosols some 134 Mtons is generated over the subcontinent. About 60 Mtons year(-1) are deposited, and approximately 29 Mtons year(-1) are exported westward over the Atlantic Ocean and 45 Mtons year(-1) eastward over the Indian Ocean. Twenty-six million tons of the 74 Mtons of aerosols exported annually to the adjacent oceans on each coast are a product of recirculation. Deposition within 10 degrees latitude of the coast is nearly 10 times greater on the east than on the west coast.

  • 2023.
    Törnevik, Håkan
    SMHI.
    An aerobiological model for operational forecasts of pollen concentration in the air1982Report (Other academic)
  • 2024.
    Törnevik, Håkan
    et al.
    SMHI.
    Ugnell,
    SMHI.
    Belastningsprognoser1986Report (Other academic)
  • 2025.
    Udin, Ingemar
    et al.
    SMHI, Core Services.
    Mattisson, Ingemar
    SMHI.
    Havsis- och snöinformation ur datorbearbetade satellitdata – en modellstudie1979Report (Other academic)
    Abstract [en]

    Computer programs have been developed for handling of NOAA VHRR digital data. The programs include geometric corrections, presentation of calibration data, derivation of data, variation of grey scales, different presentation forms etc. A SAAB D23 computer has been used for the computations. Line printer has mostly been used for presentation of data, but also electrostatic plotter and ink jet plotter have been used. The analogue VHRR data was digitized at the Swedish Defense Rese·arch Board. The soft ware has mainly been applied to sea ice and snow studies but also in a less degree to studies of sea surface temperature and examination of data, which was supposed to be the oil spill at platform Bravo ·in the Ekofisk area. Digital processed satellite data are more useful than photographic pictures both for sea ice and snow mapping. Quantification of snow cover and sorne ice parameters is possible, but for many purposes a multispectral data analysis is necessary in order to avoid false information. A short sea ice study with computer processed LANDSAT data has also been carried out. The soft ware used was developed at the Swedish Defense Research Board.

  • 2026.
    Valderama, Jorge
    SMHI.
    Results of a five year survey of the distribution of UREA in the Baltic sea1987Report (Other academic)
  • 2027. Vali, Germo
    et al.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Elken, Jueri
    Simulated halocline variability in the Baltic Sea and its impact on hypoxia during 1961-20072013In: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, ISSN 2169-9275, Vol. 118, no 12, p. 6982-7000Article in journal (Refereed)
    Abstract [en]

    Salinity and halocline depth variations in the Baltic Sea during 1961-2007 are studied using a three-dimensional ocean circulation model. Significant interannual and interdecadal variations in the halocline depth are found, together with distinct periods characterized either by shallow (1970-1975) or deep halocline (1990-1995). The model simulation indicates that the mean top layer salinity in the Baltic Sea is mainly controlled by the accumulated river runoff, while the mean below halocline salinity in the Baltic proper (which comprises Bornholm and Gotland basins) is more dependent on the low-pass filtered zonal wind stress, with cutoff period of 4 years, henceforth called the mean zonal wind stress. The halocline depth and stratification strength in the Baltic Sea are significantly affected by the mean zonal wind stress, while the impact of runoff is smaller. The ventilation of the halocline from bottom layers is stronger during the shallow and from surface layers during the deep halocline period. Due to changes in ventilation variations in halocline depth systematically affect bottom oxygen concentrations on seasonal and decadal, but not on interannual time scales. For instance, a deeper halocline reduces hypoxic (oxygen concentration in bottom water below 2 mL/L) and anoxic (anoxic conditions in bottom water) areas and increases the bottom oxygen concentrations in the Gulf of Finland but decreases them in the deeper parts of the Baltic proper. Model results suggest that due to undersampling during 1961-2007 mean hypoxic and anoxic areas calculated from observed profiles are underestimated by 41% and 43%, respectively.

  • 2028. Van den Dool, H. M.
    et al.
    Peng, Peitao
    Johansson, Åke
    SMHI, Research Department, Meteorology.
    Chelliah, Muthuvel
    Shabbar, Amir
    Saha, Suranjana
    Seasonal-to-decadal predictability and prediction of North American climate - The Atlantic influence2006In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 19, no 23, p. 6005-6024Article in journal (Refereed)
    Abstract [en]

    The question of the impact of the Atlantic on North American (NA) seasonal prediction skill and predictability is examined. Basic material is collected from the literature, a review of seasonal forecast procedures in Canada and the United States, and some fresh calculations using the NCEP-NCAR reanalysis data. The general impression is one of low predictability (due to the Atlantic) for seasonal mean surface temperature and precipitation over NA. Predictability may be slightly better in the Caribbean and the (sub) tropical Americas, even for precipitation. The NAO is widely seen as an agent making the Atlantic influence felt in NA. While the NAO is well established in most months, its prediction skill is limited. Year-round evidence for an equatorially displaced version of the NAO (named ED_NAO) carrying a good fraction of the variance is also found. In general the predictability from the Pacific is thought to dominate over that from the Atlantic sector, which explains the minimal number of reported Atmospheric Model Intercomparison Project (AMIP) runs that explore Atlantic-only impacts. Caveats are noted as to the question of the influence of a single predictor in a nonlinear environment with many predictors. Skill of a new one-tier global coupled atmosphere-ocean model system at NCEP is reviewed; limited skill is found in midlatitudes and there is modest predictability to look forward to. There are several signs of enthusiasm in the community about using "trends" (low-frequency variations): (a) seasonal forecast tools include persistence of last 10 years' averaged anomaly (relative to the official 30-yr climatology), (b) hurricane forecasts are based largely on recognizing a global multidecadal mode (which is similar to an Atlantic trend mode in SST), and (c) two recent papers, one empirical and one modeling, giving equal roles to the (North) Pacific and Atlantic in "explaining" variations in drought frequency over NA on a 20 yr or longer time scale during the twentieth century.

  • 2029. van den Dool, H M
    et al.
    Saha, S
    Johansson, Åke
    SMHI, Research Department, Meteorology.
    Empirical orthogonal teleconnections2000In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 13, no 8, p. 1421-1435Article in journal (Refereed)
    Abstract [en]

    A new variant is proposed for calculating functions empirically and orthogonally from a given space-time dataset. The method is rooted in multiple linear regression and yields solutions that are orthogonal in one direction, either space or time. In normal setup, one searches for that point in space, the base point (predictor). which, by linear regression, explains the most of the variance at all other points (predictands) combined. The first spatial pattern is the regression coefficient between the base point and all other points, and the first time series is taken to be the time series of the raw data at the base point. The original dataset is next reduced; that is, what has been accounted for by the first mode is subtracted out. The procedure is repeated exactly as before for the second, third, etc., modes. These new functions are named empirical orthogonal teleconnections (EOTs). This is to emphasize the similarity of EOT to both teleconnections and (biorthogonal) empirical orthogonal functions (EOFs). One has to choose the orthogonal direction for EOT. In the above description of the normal space-time setup, picking successive base points in space, the time series are orthogonal. One can reverse the role of time and space-in this case one picks base points in time, and the spatial maps will be orthogonal. If the dataset contains biorthogonal modes, the EOTs are the same for both setups and are equal to the EOFs. When applied to four commonly used datasets, the procedure was found to work well in terms of explained variance (EV) and in terms of extracting familiar patterns. In all examples the EV for EOTs was only slightly less than the optimum obtained by EOF. A numerical recipe was given to calculate EOF, starting from EOT as an initial guess. When subjected to cross validation the EOTs seem to fare well in terms of explained variance on independent data las good as EOF). The EOT procedure can be implemented very easily and has, for some (but not all) applications, advantages over EOFs. These novelties, advantages, and applications include the following. 1) One can pick certain modes (or base point) first-the order of the EOTs is free, and there is a near-infinite set of EOTs. 2) EOTs are linked to specific points in space or moments in time. 3) When linked to Row at specific moments in time, the EOT modes have undeniable physical reality. 4) When linked to flow at specific moments in time, EOTs appear to be building blocks for empirical forecast methods because one can naturally access the time derivative. 5) When linked to specific points in space, one has a rational basis to define strategically chosen points such that an analysis of the whole domain would benefit maximally from observations at these locations.

  • 2030. Van den Hurk, B
    et al.
    Hirschi, M
    Schar, C
    Lenderink, G
    Van Meijgaard, E
    Van Ulden, A
    Rockel, B
    Hagemann, S
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, R
    Soil control on runoff response to climate change in regional climate model simulations2005In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 18, no 17, p. 3536-3551Article in journal (Refereed)
    Abstract [en]

    Simulations with seven regional climate models driven by a common control climate simulation of a GCM carried out for Europe in the context of the (European Union) EU-funded Prediction of Regional scenarios and Uncertainties for Defining European Climate change risks and Effects (PRUDENCE) project were analyzed with respect to land surface hydrology in the Rhine basin. In particular, the annual cycle of the terrestrial water storage was compared to analyses based on the 40-yr ECMWF Re-Analysis (ERA-40) atmospheric convergence and observed Rhine discharge data. In addition, an analysis was made of the partitioning of convergence anomalies over anomalies in runoff and storage. This analysis revealed that most models underestimate the size of the water storage and consequently overestimated the response of runoff to anomalies in net convergence. The partitioning of these anomalies over runoff and storage was indicative for the response of the simulated runoff to a projected climate change consistent with the greenhouse gas A2 Synthesis Report on Emission Scenarios (SRES). In particular, the annual cycle of runoff is affected largely by the terrestrial storage reservoir. Larger storage capacity leads to smaller changes in both wintertime and summertime monthly mean runoff. The sustained summertime evaporation resulting from larger storage reservoirs may have a noticeable impact on the summertime surface temperature projections.

  • 2031. van den Hurk, B J J M
    et al.
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Viterbo, P
    Comparison of land surface hydrology in regional climate simulations of the Baltic Sea catchment2002In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 255, no 1-4, p. 169-193Article in journal (Refereed)
    Abstract [en]

    Simulations with a regional climate model RACMO were carried out over the catchment area of the Baltic Sea for the growing season 1995. Two different surface schemes were included which in particular differed with respect to the parameterization of runoff. In the first scheme (taken from ECHAM4), runoff is a function of the subgrid distribution of the soil moisture saturation. In the second model (taken from ECMWF), runoff is a result of deep-water drainage. A large-scale hydrological model of the catchment, HBV-Baltic, was calibrated to river discharge data and forced with observed precipitation, yielding independent comparison material of runoff of the two RACMO simulations. The simulations showed that the temporal and spatial simulation of precipitation in the area is sensitive to the choice of the land surface scheme in RACMO. This supported the motivation of analysing the land surface hydrological budgets in a coupled mode. The comparison of RACMO with HBV-Baltic revealed that the frequency distribution of runoff in the ECMWF scheme shows very little runoff variability at high frequencies, while in ECHAM4 and HBV the snow melt and (liquid) precipitation are followed by fast responding runoff events. The seasonal cycle of soil water depletion and surface evaporation was evaluated by comparison of model scores with respect to relative humidity. Results suggest that the surface evaporation in the ECMWF scheme is too strong in late spring and early summer, giving rise to too much drying later in the season. (C) 2002 Elsevier Science B.V. All rights reserved.

  • 2032. van der Gon, H. A. C. Denier
    et al.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Fountoukis, C.
    Johansson, C.
    Pandis, S. N.
    Simpson, D.
    Visschedijk, A. J. H.
    Particulate emissions from residential wood combustion in Europe revised estimates and an evaluation2015In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, no 11, p. 6503-6519Article in journal (Refereed)
    Abstract [en]

    Currently residential wood combustion (RWC) is increasing in Europe because of rising fossil fuel prices but also due to climate change mitigation policies. However, especially in small-scale applications, RWC may cause high emissions of particulate matter (PM). Recently we have developed a new high-resolution (7 x 7 km) anthropogenic carbonaceous aerosol emission inventory for Europe. The inventory indicated that about half of the total PM2.5 emission in Europe is carbonaceous aerosol and identified RWC as the largest organic aerosol source in Europe. The inventory was partly based on national reported PM emissions. Use of this organic aerosol inventory as input for two chemical transport models (CTMs), PMCAMx and EMEP MSC-W, revealed major underestimations of organic aerosol in winter time, especially for regions dominated by RWC. Interestingly, this was not universal but appeared to differ by country. In the present study we constructed a revised bottom-up emission inventory for RWC accounting for the semivolatile components of the emissions. The revised RWC emissions are higher than those in the previous inventory by a factor of 2-3 but with substantial inter-country variation. The new emission inventory served as input for the CTMs and a substantially improved agreement between measured and predicted organic aerosol was found. The revised RWC inven-tory improves the model-calculated organic aerosol significantly. Comparisons to Scandinavian source apportionment studies also indicate substantial improvements in the modelled wood-burning component of organic aerosol. This suggests that primary organic aerosol emission inventories need to be revised to include the semivolatile organic aerosol that is formed almost instantaneously due to dilution and cooling of the flue gas or exhaust. Since RWC is a key source of fine PM in Europe, a major revision of the emission estimates as proposed here is likely to influence source-receptor matrices and modelled source apportionment. Since usage of biofuels in small combustion units is a globally significant source, the findings presented here are also relevant for regions outside of Europe.

  • 2033. van Lipzig, Nicole P. M.
    et al.
    Schroeder, Marc
    Crewell, Susanne
    Ament, Felix
    Chaboureau, Jean-Pierre
    Loehnert, Ulrich
    Matthias, Volker
    van Meijgaard, Erik
    Quante, Markus
    Willén, Ulrika
    SMHI, Research Department, Climate research - Rossby Centre.
    Yen, Wenchieh
    Model predicted low-level cloud parameters - Part I: Comparison with observations from the BALTEX Bridge Campaigns2006In: Atmospheric research, ISSN 0169-8095, E-ISSN 1873-2895, Vol. 82, no 1-2, p. 55-82Article in journal (Refereed)
    Abstract [en]

    The BALTEX Bridge Campaigns (BBC), which were held in the Netherlands in 2001 and 2003 around the Cabauw Experimental Site for Atmospheric Research (CESAR), have provided detailed information on clouds. This paper is an illustration of how these measurements can be used to investigate whether 'state-of-the-art' atmospheric models are capable of adequately representing clouds. Here, we focus on shallow low-level clouds with a substantial amount of liquid water. In situ, ground-based and satellite remote sensing measurements were compared with the output of three non-hydrostatic regional models (Lokal-Modell, LM.- M&so-NH: fifth-generation Mesoscale Model, MM5) and two hydrostatic regional climate models (Regional Atmospheric Climate Model version 2, RACMO2; Rossby Centre Atmospheric Model, RCA). For the two selected days, Meso-NH and MM5 reproduce the measured vertical extent of the shallow clouds, but the liquid water content of the clouds is generally overestimated. In LM and the climate models the inversion is too weak and located at a level too close to the surface resulting in an overestimation of the vertical extent of the clouds. A sensitivity integration with RACM02 shows that the correspondence between model output and measurements can be improved by a doubling of the vertical resolution; this induces an increase in the modelled inversion strenath and cloud top pressure. LM and Meso-NH underestimate the lifetime of clouds. A comparison between model output and cloud cover derived from the Moderate Resolution Imaging Spectrometer (MODIS) indicates that this deficiency is not due to advection of too small cloud systems,- it is rather due to an overestimation of the variability in the vertical velocity. All models overestimate the specific humidity near the surface and underestimate it at higher atmospheric levels, indicating that the models underestimate the mixing of moisture in the boundary layer. This deficiency is slightly reduced by inclusion of parameterised shallow convection in the non-hydrostatic models, which enhances the mixing of heat and moisture in the boundary layer. Consequently, the explicitly resolved updrafts weaken resulting in reduced condensation rates and lower liquid water path. The temporal variability of cloud occurrence is hardly affected by inclusion of parameterised shallow convection. (c) 2006 Elsevier B.V. All rights reserved.

  • 2034. van Loon, M.
    et al.
    Vautard, R.
    Schaap, M.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Brandt, J.
    Builtjes, P. J. H.
    Christensen, J. H.
    Cuvelier, C.
    Graff, A.
    Jonson, J. E.
    Krol, M.
    Langner, J.
    Roberts, P.
    Rouil, L.
    Stern, R.
    Tarrason, L.
    Thunis, P.
    Vignati, E.
    White, L.
    Wind, P.
    Evaluation of long-term ozone simulations from seven regional air quality models and their ensemble2007In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 41, no 10, p. 2083-2097Article in journal (Refereed)
    Abstract [en]

    Long-term ozone simulations from seven regional air quality models, the Unified EMEP model, LOTOS-EUROS, CHIMERE, RCG, MATCH, DEHM and TM5, are intercompared and compared to ozone measurements within the framework of the EuroDelta experiment, designed to assess air quality improvement at the European scale in response to emission reduction scenarios for 2020. Modelled ozone concentrations for the year 2001 are evaluated. The models reproduce the main features of the ozone diurnal cycle, but generally overestimate daytime ozone, LOTOS-EUROS and RCG have a more pronounced diurnal cycle variation than observations, while the reverse occurs for TM5. CHIMERE has a large positive bias, which can be explained by a systematic bias in boundary conditions. The other models and the "ensemble model", whose concentrations are by definition averaged over all models, represent accurately the diurnal cycle. The ability of the models to simulate day-to-day daily ozone average or maxima variability is examined by means of percentiles, root mean square errors and correlations. In general, daily maxima are better simulated than daily averages, and summertime concentrations are better simulated than wintertime concentrations. Summertime correlations range between 0.5 and 0.7 for daily averages and 0.6 and 0.8 for daily maxima. Two health-related indicators are used, the number of days of exceedance of the 120 mu g m(-3) threshold for the daily maximal 8-h ozone concentration and the SOMO35. Both are well reproduced in terms of frequency, but the simultaneity of occurrence of exceedance days between observations and simulations is not well captured.

  • 2035. van Meijgaard, E
    et al.
    Andrae, Ulf
    SMHI, Research Department, Meteorology.
    Rockel, B
    Comparison of model predicted cloud parameters and surface radiative fluxes with observations on the 100 km scale2001In: Meteorology and atmospheric physics (Print), ISSN 0177-7971, E-ISSN 1436-5065, Vol. 77, no 1-4, p. 109-130Article in journal (Refereed)
    Abstract [en]

    Cloud parameters and surface radiative fluxes predicted by regional atmospheric models are directly compared with observations for a 10-day period in late summer 1995 characterized by predominantly large-scale synoptic conditions. Observations of total cloud cover and Vertical cloud structure are inferred from measurements with a groundbased network of Lidar ceilometers and IR-radiometers and from satellite observations on a 100 kilometer scale. Groundbased observations show that at altitudes below 3 km, implying liquid water clouds, there is a considerable portion of optically non-opaque clouds. Vertical distributions of cloud temperatures simultaneously inferred from the groundbased infrared radiometer network and from satellite can only be reconciled if the occurrence of optically thin cloud structures at mid- and high tropospheric levels is assumed to be frequent. Results of three regional atmospheric models, i.e. the GKSS-REMO, SMHI-HIRLAM. and KNMI-RACMO, are quantitatively compared with the observations. The main finding is that all models predict too much cloud amount at low altitude below 900 hPa, which is then compensated by an underestimation of cloud amount around 800 hPa. This is likely to be related with the finding that all models tend to underestimate the planetary boundary layer height. All models overpredict the high-level cloud amount albeit it is difficult to quantify to what extent due to the frequent presence of optically thin clouds. Whereas reasonably alike in cloud parameters, the models differ considerably in radiative fluxes. One model links a well matching incoming solar radiation to a radiatively transparent atmosphere over a too cool surface, another model underpredicts incoming solar radiation at the surface due to a too strong cloud feedback to radiation, the last model represents all surface radiative fluxes quite well on average: but underestimates the sensitivity of atmospheric transmissivity to cloud amount.

  • 2036. Van Pham, Trang
    et al.
    Brauch, Jennifer
    Dieterich, Christian
    SMHI, Research Department, Oceanography.
    Frueh, Barbara
    Ahrens, Bodo
    New coupled atmosphere-ocean-ice system COSMO-CLM/NEMO: assessing air temperature sensitivity over the North and Baltic Seas2014In: Oceanologia, ISSN 0078-3234, Vol. 56, no 2, p. 167-189Article in journal (Refereed)
    Abstract [en]

    This paper introduces a newly established coupled atmosphere-ocean-ice system with the regional climate model COSMO-CLM and the ocean-sea-ice model NEMO for the North and Baltic Seas. These two models are linked via the OASIS3 coupler. Experiments with the new coupled system and with the stand-alone COSMO-CLM model forced by ERA-Interim re-analysis data over the period from 1985 to 1994 for the CORDEX Europe domain are carried out. The evaluation results of the coupled system show 2-m temperature biases in the range from -2.5 to 3 K. Simulated 2-m temperatures are generally colder in the coupled than in the uncoupled system, and temperature differences vary by season and space. The coupled model shows an improvement compared with the stand-alone COSMO-CLM in terms of simulating 2-m temperature. The difference in 2-m temperature between the two experiments are explained as downwind cooling by the colder North and Baltic Seas in the coupled system.

  • 2037. van Pul, Addo
    et al.
    Hertel, Ole
    Geels, Camilla
    Dore, Anthony J.
    Massimo, Vieno
    van Jaarsveld, Hans A.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Schaap, Martijn
    Fagerli, Hilde
    Modelling of the Atmospheric Transport and Deposition of Ammonia at a National and Regional Scale2009In: in Atmospheric Ammonia - Detecting emission changes and environmental impacts., Springer, 2009, p. 301-356Chapter in book (Other academic)
  • 2038. van Pul, Addo
    et al.
    Reis, Stefan
    Dore, Tony
    Xuejun, Liu
    Hilde, Fagerli
    Geels, Camilla
    Hertel, Ole
    Kruijt Roy, Wichink
    Kryza, Maciej
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Vieno, Massimo
    Ron, Smith
    Eiko, Nemitz
    Modelling the National and Regional Transport and Deposition of Ammonia2009In: Atmospheric Ammonia - Detecting emission changes and environmental impacts., Springer, 2009, p. 409-421Chapter in book (Other academic)
  • 2039. van Vliet, Michelle T. H.
    et al.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Strombäck, Lena
    SMHI, Research Department, Hydrology.
    Capell, Réne
    SMHI, Research Department, Hydrology.
    Ludwig, Fulco
    European scale climate information services for water use sectors2015In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 528, p. 503-513Article in journal (Refereed)
    Abstract [en]

    This study demonstrates a climate information service for pan-European water use sectors that are vulnerable to climate change induced hydrological changes, including risk and safety (disaster preparedness), agriculture, energy (hydropower and cooling water use for thermoelectric power) and environment (water quality). To study the climate change impacts we used two different hydrological models forced with an ensemble of bias-corrected general circulation model (GCM) output for both the lowest (2.6) and highest (8.5) representative concentration pathways (RCP). Selected indicators of water related vulnerability for each sector were then calculated from the hydrological model results. Our results show a distinct north-south divide in terms of climate change impacts; in the south the water availability will reduce while in the north water availability will increase. Across different climate models precipitation and streamflow increase in northern Europe and decrease in southern Europe, but the latitude at which this change occurs varies depending on the GCM. Hydrological extremes are increasing over large parts of Europe. The agricultural sector will be affected by reduced water availability (in the south) and increased drought. Both streamflow and soil moistures droughts are projected to increase in most parts of Europe except in northern Scandinavia and the Alps. The energy sector will be affected by lower hydropower potential in most European countries and reduced cooling water availability due to higher water temperatures and reduced summer river flows. Our results show that in particular in the Mediterranean the pressures are high because of increasing drought which will have large impacts on both the agriculture and energy sectors. In France and Italy this is combined with increased flood hazards. Our results show important impacts of climate change on European water use sectors indicating a clear need for adaptation. (C) 2015 Published by Elsevier B.V.

  • 2040. Vanniere, Benoit
    et al.
    Demory, Marie-Estelle
    Vidale, Pier Luigi
    Schiemann, Reinhard
    Roberts, Malcolm J.
    Roberts, Christopher D.
    Matsueda, Mio
    Terray, Laurent
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Senan, Retish
    Multi-model evaluation of the sensitivity of the global energy budget and hydrological cycle to resolution2019In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 52, no 11, p. 6817-6846Article in journal (Refereed)
  • 2041. Vautard, R.
    et al.
    Schaap, M.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Brandt, J.
    Builtjes, P. J. H.
    Christensen, J. H.
    Cuvelier, C.
    Foltescu, Valentin
    SMHI.
    Graff, A.
    Kerschbaumer, A.
    Krol, M.
    Roberts, P.
    Rouil, L.
    Stern, R.
    Tarrason, L.
    Thunis, P.
    Vignati, E.
    Wind, P.
    Skill and uncertainty of a regional air quality model ensemble2009In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 43, no 31, p. 4822-4832Article in journal (Refereed)
    Abstract [en]

    Recently several regional air quality projects were carried out to support the negotiation under the Clean Air For Europe (CAFE) programme by predicting the impact of emission control policies with an ensemble of models. Within these projects, CITYDELTA and EURODELTA, the fate of air quality at the scale of European cities or that of the European continent was studied using several models. In this article we focus on the results of EURODELTA. The predictive skill of the ensemble of models is described for ozone, nitrogen dioxide and secondary inorganic compounds, and the uncertainty in air quality modelling is examined through the model ensemble spread of concentrations. For ozone daily maxima the ensemble spread origin differs from one region to another. In the neighbourbood of cities or in mountainous areas the spread of predicted values does not span the range of observed data, due to poorly resolved emissions or complex-terrain meteorology. By contrast in Atlantic and North Sea coastal areas the spread of predicted values is found to be larger than the observations. This is attributed to large differences in the boundary conditions used in the different models. For NO2 daily averages the ensemble spread is generally too small compared with observations. This is because models miss highest values occurring in stagnant meteorology in stable boundary layers near cities. For secondary particulate matter compounds the simulated concentration spread is more balanced, observations falling nearly equiprobably within the ensemble, and the spread originates both from meteorology and aerosol chemistry and thermodynamics. (C) 2008 Published by Elsevier Ltd.

  • 2042. Vautard, R.
    et al.
    Van Loon, M.
    Schaap, M.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Brandt, J.
    Builtjes, P. J. H.
    Christensen, J. H.
    Cuvelier, C.
    Graff, A.
    Jonson, J. E.
    Krol, M.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Roberts, P.
    Rouil, L.
    Stern, R.
    Tarrason, L.
    Thunis, P.
    Vignati, E.
    White, L.
    Wind, P.
    Is regional air quality model diversity representative of uncertainty for ozone simulation?2006In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 33, no 24, article id L24818Article in journal (Refereed)
    Abstract [en]

    We examine whether seven state-of-the-art European regional air quality models provide daily ensembles of predicted ozone maxima that encompass observations. Using tools borrowed from the evaluation of ensemble weather forecasting, we analyze statistics of simulated ensembles of ozone daily maxima over an entire summer season. Although the model ensemble overestimates ozone, the distribution of simulated concentrations is representative of the uncertainty. The spread of simulations is due to random fluctuations resulting from differences in model formulations and input data, but also to the spread between individual model systematic biases. The ensemble average skill increases as the spread decreases. The skill of the ensemble in giving probabilistic predictions of threshold exceedances is also demonstrated. These results allow for optimism about the ability of this ensemble to simulate the uncertainty of the impact of emission control scenarios.

  • 2043. Vautard, Robert
    et al.
    Gobiet, Andreas
    Jacob, Daniela
    Belda, Michal
    Colette, Augustin
    Deque, Michel
    Fernandez, Jesus
    Garcia-Diez, Markel
    Goergen, Klaus
    Guettler, Ivan
    Halenka, Tomas
    Karacostas, Theodore
    Katragkou, Eleni
    Keuler, Klaus
    Kotlarski, Sven
    Mayer, Stephanie
    van Meijgaard, Erik
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Patarcic, Mirta
    Scinocca, John
    Sobolowski, Stefan
    Suklitsch, Martin
    Teichmann, Claas
    Warrach-Sagi, Kirsten
    Wulfmeyer, Volker
    Yiou, Pascal
    The simulation of European heat waves from an ensemble of regional climate models within the EURO-CORDEX project2013In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 41, no 9-10, p. 2555-2575Article in journal (Refereed)
    Abstract [en]

    The ability of a large ensemble of regional climate models to accurately simulate heat waves at the regional scale of Europe was evaluated. Within the EURO-CORDEX project, several state-of-the art models, including non-hydrostatic meso-scale models, were run for an extended time period (20 years) at high resolution (12 km), over a large domain allowing for the first time the simultaneous representation of atmospheric phenomena over a large range of spatial scales. Eight models were run in this configuration, and thirteen models were run at a classical resolution of 50 km. The models were driven with the same boundary conditions, the ERA-Interim re-analysis, and except for one simulation, no observations were assimilated in the inner domain. Results, which are compared with daily temperature and precipitation observations (ECA&D and E-OBS data sets) show that, even forced by the same re-analysis, the ensemble exhibits a large spread. A preliminary analysis of the sources of spread, using in particular simulations of the same model with different parameterizations, shows that the simulation of hot temperature is primarily sensitive to the convection and the microphysics schemes, which affect incoming energy and the Bowen ratio. Further, most models exhibit an overestimation of summertime temperature extremes in Mediterranean regions and an underestimation over Scandinavia. Even after bias removal, the simulated heat wave events were found to be too persistent, but a higher resolution reduced this deficiency. The amplitude of events as well as the variability beyond the 90th percentile threshold were found to be too strong in almost all simulations and increasing resolution did not generally improve this deficiency. Resolution increase was also shown to induce large-scale 90th percentile warming or cooling for some models, with beneficial or detrimental effects on the overall biases. Even though full causality cannot be established on the basis of this evaluation work, the drivers of such regional differences were shown to be linked to changes in precipitation due to resolution changes, affecting the energy partitioning. Finally, the inter-annual sequence of hot summers over central/southern Europe was found to be fairly well simulated in most experiments despite an overestimation of the number of hot days and of the variability. The accurate simulation of inter-annual variability for a few models is independent of the model bias. This indicates that internal variability of high summer temperatures should not play a major role in controlling inter-annual variability. Despite some improvements, especially along coastlines, the analyses conducted here did not allow us to generally conclude that a higher resolution is clearly beneficial for a correct representation of heat waves by regional climate models. Even though local-scale feedbacks should be better represented at high resolution, combinations of parameterizations have to be improved or adapted accordingly.

  • 2044. Vautard, Robert
    et al.
    Gobiet, Andreas
    Sobolowski, Stefan
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Stegehuis, Annemiek
    Watkiss, Paul
    Mendlik, Thomas
    Landgren, Oskar
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Teichmann, Claas
    Jacob, Daniela
    The European climate under a 2 degrees C global warming2014In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 9, no 3, article id 034006Article in journal (Refereed)
    Abstract [en]

    A global warming of 2 degrees C relative to pre-industrial climate has been considered as a threshold which society should endeavor to remain below, in order to limit the dangerous effects of anthropogenic climate change. The possible changes in regional climate under this target level of global warming have so far not been investigated in detail. Using an ensemble of 15 regional climate simulations downscaling six transient global climate simulations, we identify the respective time periods corresponding to 2 degrees C global warming, describe the range of projected changes for the European climate for this level of global warming, and investigate the uncertainty across the multi-model ensemble. Robust changes in mean and extreme temperature, precipitation, winds and surface energy budgets are found based on the ensemble of simulations. The results indicate that most of Europe will experience higher warming than the global average. They also reveal strong distributional patterns across Europe, which will be important in subsequent impact assessments and adaptation responses in different countries and regions. For instance, a North-South (West-East) warming gradient is found for summer (winter) along with a general increase in heavy precipitation and summer extreme temperatures. Tying the ensemble analysis to time periods with a prescribed global temperature change rather than fixed time periods allows for the identification of more robust regional patterns of temperature changes due to removal of some of the uncertainty related to the global models' climate sensitivity.

  • 2045.
    Vedin, Haldo
    SMHI.
    Extrem arealnederbörd i Sverige1986Report (Other academic)
  • 2046.
    Vedin, Haldo
    SMHI.
    FREQUENCY OF RARE WEATHER EVENTS DURING PERIODS OF EXTREME CLIMATE1990In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 72, no 2, p. 151-155Article in journal (Refereed)
  • 2047.
    Vedin, Haldo
    et al.
    SMHI.
    Alexandersson, Hans
    SMHI.
    Persson, Magnus
    SMHI.
    Utnyttjande av persistens i temperatur och nederbörd för vårflödesprognoser1991Report (Other academic)
  • 2048.
    Vedin, Haldo
    et al.
    SMHI.
    Andersson, C.
    SMHI.
    E 66 - Linderödsåsen - klimatförhållanden1987Report (Other academic)
  • 2049.
    Vedin, Haldo
    et al.
    SMHI.
    Andersson, C.
    SMHI.
    Extrema köldperioder i Stockholm1985Report (Other academic)
  • 2050.
    Vedin, Haldo
    et al.
    SMHI.
    Andersson, C.
    SMHI.
    Spridningsberäkningar för Kockums Plåtteknik, Ronneby. 21987Report (Other academic)
38394041424344 2001 - 2050 of 2199
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. 2.35.7
|