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  • 101.
    Arneborg, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Jansson, Par
    Staalstrom, Andre
    Broström, Göran
    Tidal Energy Loss, Internal Tide Radiation, and Local Dissipation for Two-Layer Tidal Flow over a Sill2017Inngår i: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 47, nr 7, s. 1521-1538Artikkel i tidsskrift (Fagfellevurdert)
  • 102. Arnold, S. R.
    et al.
    Emmons, L. K.
    Monks, S. A.
    Law, K. S.
    Ridley, D. A.
    Turquety, S.
    Tilmes, S.
    Thomas, J. L.
    Bouarar, I.
    Flemming, J.
    Huijnen, V.
    Mao, J.
    Duncan, B. N.
    Steenrod, S.
    Yoshida, Y.
    Langner, Joakim
    SMHI, Forskningsavdelningen, Luftmiljö.
    Long, Y.
    Biomass burning influence on high-latitude tropospheric ozone and reactive nitrogen in summer 2008: a multi-model analysis based on POLMIP simulations2015Inngår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, nr 11, s. 6047-6068Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have evaluated tropospheric ozone enhancement in air dominated by biomass burning emissions at high latitudes (>50 degrees N) in July 2008, using 10 global chemical transport model simulations from the POLMIP multimodel comparison exercise. In model air masses dominated by fire emissions, Delta O-3/Delta CO values ranged between 0.039 and 0.196 ppbv ppbv(-1) (mean: 0.113 ppbv ppbv(-1)) in freshly fire-influenced air, and between 0.140 and 0.261 ppbv ppb(-1) (mean: 0.193 ppbv) in more aged fire-influenced air. These values are in broad agreement with the range of observational estimates from the literature. Model Delta PAN/Delta CO enhancement ratios show distinct groupings according to the meteorological data used to drive the models. ECMWF-forced models produce larger Delta PAN/Delta CO values (4.47 to 7.00 pptv ppbv(-1)) than GEOS5-forced models (1.87 to 3.28 pptv ppbv(-1)), which we show is likely linked to differences in efficiency of vertical transport during poleward export from mid-latitude source regions. Simulations of a large plume of biomass burning and anthropogenic emissions exported from towards the Arctic using a Lagrangian chemical transport model show that 4-day net ozone change in the plume is sensitive to differences in plume chemical composition and plume vertical position among the POLMIP models. In particular, Arctic ozone evolution in the plume is highly sensitive to initial concentrations of PAN, as well as oxygenated VOCs (acetone, acetaldehyde), due to their role in producing the peroxyacetyl radical PAN precursor. Vertical displacement is also important due to its effects on the stability of PAN, and subsequent effect on NOx abundance. In plumes where net ozone production is limited, we find that the lifetime of ozone in the plume is sensitive to hydrogen peroxide loading, due to the production of HOx from peroxide photolysis, and the key role of HO2 + O-3 in controlling ozone loss. Overall, our results suggest that emissions from biomass burning lead to large-scale photochemical enhancement in high-latitude tropospheric ozone during summer.

  • 103. Ashcroft, Linden
    et al.
    Coll, Joan Ramon
    Gilabert, Alba
    Domonkos, Peter
    Brunet, Manola
    Aguilar, Enric
    Castella, Merce
    Sigro, Javier
    Harris, Ian
    Undén, Per
    SMHI, Forskningsavdelningen, Meteorologi.
    Jones, Phil
    A rescued dataset of sub-daily meteorological observations for Europe and the southern Mediterranean region, 1877-20122018Inngår i: Earth System Science Data, ISSN 1866-3508, E-ISSN 1866-3516, Vol. 10, nr 3, s. 1613-1635Artikkel i tidsskrift (Fagfellevurdert)
  • 104. Astrom, Christofer
    et al.
    Astrom, Daniel Oudin
    Andersson, Camilla
    SMHI, Forskningsavdelningen, Luftmiljö.
    Ebi, Kristie L.
    Forsberg, Bertil
    Vulnerability Reduction Needed to Maintain Current Burdens of Heat-Related Mortality in a Changing Climate-Magnitude and Determinants2017Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 14, nr 7, artikkel-id 741Artikkel i tidsskrift (Fagfellevurdert)
  • 105. Astrom, Christofer
    et al.
    Ebi, Kristie L.
    Langner, Joakim
    SMHI, Forskningsavdelningen, Luftmiljö.
    Forsberg, Bertil
    Developing a Heatwave Early Warning System for Sweden: Evaluating Sensitivity of Different Epidemiological Modelling Approaches to Forecast Temperatures2015Inngår i: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 12, nr 1, s. 254-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Over the last two decades a number of heatwaves have brought the need for heatwave early warning systems (HEWS) to the attention of many European governments. The HEWS in Europe are operating under the assumption that there is a high correlation between observed and forecasted temperatures. We investigated the sensitivity of different temperature mortality relationships when using forecast temperatures. We modelled mortality in Stockholm using observed temperatures and made predictions using forecast temperatures from the European Centre for Medium-range Weather Forecasts to assess the sensitivity. We found that the forecast will alter the expected future risk differently for different temperature mortality relationships. The more complex models seemed more sensitive to inaccurate forecasts. Despite the difference between models, there was a high agreement between models when identifying risk-days. We find that considerations of the accuracy in temperature forecasts should be part of the design of a HEWS. Currently operating HEWS do evaluate their predictive performance; this information should also be part of the evaluation of the epidemiological models that are the foundation in the HEWS. The most accurate description of the relationship between high temperature and mortality might not be the most suitable or practical when incorporated into a HEWS.

  • 106. Astrom, Christofer
    et al.
    Orru, Hans
    Rocklov, Joacim
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ebi, Kristie L.
    Forsberg, Bertil
    Heat-related respiratory hospital admissions in Europe in a changing climate: a health impact assessment2013Inngår i: BMJ Open, ISSN 2044-6055, E-ISSN 2044-6055, Vol. 3, nr 1, artikkel-id e001842Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 107.
    Axe, Philip
    SMHI, Forskningsavdelningen, Oceanografi.
    Oceanographic applications of coastal radar2013Rapport (Annet vitenskapelig)
    Abstract [en]

    This report documents the 2010 Coastal Radar Workshop organised by the Swedish Meteorological and Hydrological Institute with support from the Swedish Environmental Protection Agency. The aim of the report is to provide background information on coastal oceanographic radar for a wider professional audience and to provide a basis for further Nordic cooperation in the field of oceanographic (coastal) radar with the ultimate aim of establishing a Nordic network covering (initially) the shared waters of the Skagerrak and Kattegat.Information on currents in near real time is seldom available when needed by many day to day applications and services. Data are needed for safe and efficient ship routing in narrow areas of hightraffic such as in the northern Kattegat, Danish Straits, Bornholm Strait and the Gulf of Finland. At the entrances of major ports and where [environmentally] dangerous cargos are carried currentinformation can be of crucial importance. For this reason the Swedish Maritime Administration maintains current observations in critical areas. However, these are point measurements and in the waters mentioned above topography may alter currents both in strength and direction in nearby areas. Hence, complementary spatial information on the behaviour of currents is preferable.Access to high quality, spatially resolved current information is critical both for effective oil spill containment and greatly increases the chances for successful outcomes of search and rescue operations. Combining data from models and observations will reduce the search area in rescue operations and make planning and combat of oil spill operations more efficient. In addition, areal near real time current observations are likely to promote research and development related to fish larvae transports, the spread of alien species, improve oceanographic models and lead to the better understanding of ocean and coastal sea processes.The present workshop highlights and extends the knowledge base on European and US experiences, user needs and available technical systems for areal current observations. Taking into account thatNordic views are usually coherent, opportunities to coordinate and cooperate in establishing and running an operational pilot system at a Nordic level seem realistic. The workshop intends to lay the foundation for carrying this work further.

  • 108.
    Axe, Philip
    SMHI, Forskningsavdelningen, Oceanografi.
    Temporal and spatial monitoring of eutrophication variables in CEMP2008Rapport (Annet vitenskapelig)
    Abstract [en]

    The OSPAR Revised Eutrophication Monitoring Programme (ETG 05/3/Info.1-E) requests that nutrient "monitoring should include sufficient samples to confirm that the maximum winter nutrient concentration has been determined", while para. 7 of the Terms of Reference for the preparation of guidance on the spatial and temporal resolution of monitoring for nutrients and eutrophication effects (ICG 003) states that "there are at least nine different water types covered by the OSPAR Maritime Area"..."guidance must, therefore, be at least complex enough to cover each type with sufficient clarity to guide contracting parties in their evaluation of the temporal and spatial coverage required to adequately assess the relevant water body".This document summarises the national reports submitted to the OSPAR Intersessional Correspondence Group on Eutrophication Monitoring, and highlights common problems faced in the monitoring of (primarily) inorganic nutrients and chlorophyll. In addition, it presents tests of different approaches to solving the spatial and temporal sampling problems associated with delivering marine eutrophication data.Based on tests of model data, monthly sampling appears adequate to give a good estimate of annual mean concentrations. Buoy data suggests that this would not be sufficient where there is tidal variability. It was not possible to determine maximum concentrations through a practical ship sampling scheme, or by using extreme value statistics.The optimum sampling programme to observe rapid events is likely to be a combination of ferrybox systems, which appear to be reliable and give both good spatial and temporal coverage, combined with buoy observations. To ensure data of sufficient quality, these must be controlled against conventional research vessel observations. Research vessels still have a role in seasonal mapping, and in providing data of sufficient quality for trend analysis from a large area. This is likely to remain so, at leastuntil technologies such as gliders and optical nutrient sensors become widely available and capable of delivering reliable, high quality data.

  • 109.
    Axe, Philip
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Hansson, Martin
    SMHI, Samhälle och säkerhet.
    Håkansson, Bertil
    SMHI, Forskningsavdelningen, Oceanografi.
    The National Monitoring Programme in the Kattegat and Skagerrak2004Rapport (Annet vitenskapelig)
    Abstract [en]

    To facilitate the development of the OSPAR eutrophication monitoring programme, this report presents the statistical strength of trends reported in the 2002 Common Procedure Report1. After correcting nutrient records to a reference salinity of 30 psu (to compensate for the effects of dilution), ortho-phosphate concentration exhibits a significant negative trend in the inshore Kattegat and Skagerrak. Significant decreases in silicate were observed in all areas. These changes caused changes in Redfield and other nutrient ratios. Indirect indicators of eutrophication (autumn, bottom oxygen concentration; growing-season chlorophyll-a concentration) exhibited significant trends. Chlorophyll-a concentration increased in the Skagerrak, while oxygen concentration decreased in all areas, apart from the inshore Kattegat.Spatial characteristics of the study area were tested using probability mapping. The Kattegat was found to be well represented by 8 divisions, while 4 areas were suitable Skagerrak.Changes in the current monitoring programme were not recommended. Increasing sampling frequency could interfere with the statistical independence of measurements – an assumption for the validity of trend calculations. Filling gaps in the existing time series improves the statistical significance of observed trends. This requires effective data exchange between monitoring institutions, and possibly data archaeology.

  • 110.
    Axe, Philip
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Lindow, Helma
    SMHI, Samhälle och säkerhet.
    Hydrographic Conditions Around Offshore Banks2005Rapport (Annet vitenskapelig)
    Abstract [en]

    This report details the results of an investigation into hydrographic and hydrochemical conditions over ten offshore banks around the coast of south Sweden. Four of these banks are situated in the Kattegat. The remainder lie in the southern and western Baltic Proper. The investigation included field sampling, where each bank was visited on one occasion, and the temperature and salinity structure mapped while the concentrations of nutrients were measured. These data were analysed, and results compared and complemented with predictions from operational numerical models (for currents and waves). The banks are areas with strong horizontal gradients in temperature and salinity. They influence the large scale circulation, steering mean currents through the deeper water, resulting in the mean currents over the banks being weak. The influence of short term wind events are significant however, with intense, short-lived currents occurring over the banks. Nutrient concentrations in the waters above the banks were very similar to those in the adjacent basins. Immediately over the bottom however, silicate concentrations were often higher than at similar depths away from the banks. Similarly, oxygen saturation immediately above the bottom was frequently lower than in mid-water at the same depth. In the Kattegat, large areas are at risk from seasonal oxygen deficiency. The shallow nature of the banks however often means that they escape the worst impacts.

  • 111.
    Axe, Philip
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Wesslander, Karin
    SMHI, Samhälle och säkerhet.
    Kronsell, Johan
    SMHI, Samhälle och säkerhet.
    Confidence rating for OSPAR COMP2012Rapport (Annet vitenskapelig)
    Abstract [sv]

    Medlemsländerna inom EU har undertecknat Havsmiljödirektivet samt Ramdirektivet för Vatten och har därmed förpliktat sig att uppnå ”God” eller ”God miljö-” status inom sina marina miljöer inom en viss tid, eller ta fram åtgärder. Det finns därför ett behov att utvärdera mätprogrammen som levererar data till sådana statusbedömningar, som en del av konfidensbedömningen av hela statusbedömningen. Inom OSPAR Konventionen för Skyddet av Nordost Atlanten, har Tyskland och Nederländerna presenterat ett förslag för hur man skulle kunna utföra en sådan utvärdering. Den här rapporten beskriver resultat när metoden användes med svenska data från Västerhavet (inklusive Öresund, som möjligtvis ska ingå i Större Nordsjöns region under Marina Strategin). Övergödningsvariablernas salthaltsvariation undersöktes. I Kattegatt var den oorganiska närsaltsvariabiliteten minst vid den högsta salthalten, detta tyder på att en pålitlig bedömning av övergödning kan göras enklare med utsjödata än med data från den mer dynamiska kustzonen. När man tittar på mätprogrammets täckning, syns det att horisontala gradienter i bedömningsvariabler (ofta säsongsmedlen) varierar med mindre än 30 % mellan stationer. Detta visar på en rimlig täckning, även om flera stationer skulle förbättra programmet. Om man tittar på varje station för sig, är nuvarande provtagning i djupled tillräcklig, förutom för klorofyll a och oorganiska närsalter under växtsäsongen. Provtagningsfrekvensen räcker för totala närsaltshalter, men är inte tillräcklig för oorganiska närsalter samt, i Öresund, för koncentrationen av syre i djupvattnet. Den otillräckliga provtagningen av klorofyll a och oorganiska närsalter kan förbättras ganska enkelt om en autoanalysator med två kanaler (nitrit + nitrat, samt ortofosfat) monteras på de nuvarande ferryboxsystem som används. Alternativet att använda bojar och traditionella mätplattformar skulle vara dyrare.

  • 112.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    BSRA-15: A Baltic Sea Reanalysis 1990–20042013Rapport (Annet vitenskapelig)
    Abstract [en]

    Oceanographic observations are often of high quality but are available only with low resolution in time and space. On the other hand, model fields have high resolution in time and space but are not necessarily in agreement with observations. To bridge the gap between these very different kinds of data sets, a reanalysis can be made, which means that fixed versions of the numerical model and the data assimilation system are used to analyse a period of several years. This report describes an oceanographic reanalysis covering the period 1990 to 2004 (15 whole years). The horizontal resolution is 3 nautical miles in the Baltic Sea and 12 nautical miles in the North Sea, and the vertical resolution varies between 4 meters near the surface to 60 meters in the deepest part (up to 24 vertical layers). The time resolution of the reanalysis product is 6 hours. The numerical ocean model used is HIROMB (High-Resolution Operational Model for the Baltic), version 3.0. The data assimilation method used in this reanalysis is the Successive Corrections Method (SCM) for salinity and temperature, whereas ice observations in terms of ice charts were simply interpolated. The result looks good in terms of sea levels, ice fields, and salinity and temperature structure, whereas currents have not been validated. This oceanographic reanalysis was probably the first one ever for the Baltic Sea (when it was done in 2005) and may serve as a starting point before longer, more advanced reanalyses are produced.

  • 113.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    On the variability of Baltic Sea deepwater mixing1998Inngår i: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, Vol. 103, nr C10, s. 21667-21682Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Historical oceanographic data from the period 1964-1997 from two deep subbasins (the Gotland Deep and the Landsort Deep) in the Baltic Sea have been analyzed, by using a budget method on stagnant periods, with respect to vertical diffusion and vertical energy flux density in the deep water. It was found that the rate of deepwater mixing varied with the seasons, with higher rates in fall and winter compared to spring and summer. Further, according to the analyzed data, the downward flux density of energy available for vertical diffusion decreased with increasing depth in the Gotland Deep. In the Landsort Deep, however, the flux density increased somewhat, probably because of topographic concentration of the energy, before decreasing toward the bottom. Moreover, the vertical energy flux densities were compared with the expected flux density from the local wind. It is proposed that in the Gotland Deep, which is outside the coastal boundary layer, the observed deepwater mixing is dominated by the energy input from the wind via inertial currents and internal waves. In the Landsort Deep, however, which is within the coastal boundary layer, the expected flux density of energy from the local wind cannot explain the observed rate of work against the buoyancy forces. It is proposed that the active coastal boundary layer plays a central role in the transfer of energy to mixing processes in the deep water.

  • 114.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Wind-driven internal waves and Langmuir circulations in a numerical ocean model of the southern Baltic Sea2002Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 107, nr C11, artikkel-id 3204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    [1] A one-dimensional numerical ocean model of the southern Baltic Sea is used to investigate suitable parameterizations of unresolved turbulence and compare with available observations. The turbulence model is a k-epsilon model that includes extra source terms P-IW and P-LC of turbulent kinetic energy (TKE) due to unresolved, breaking internal waves and Langmuir circulations, respectively. As tides are negligible in the Baltic Sea, topographic generation of internal wave energy (IWE) is neglected. Instead, the energy for deepwater mixing in the Baltic Sea is provided by the wind. At each level the source term P-IW is assumed to be related to a vertically integrated pool of IWE, E-0, and the buoyancy frequency N at the same level, according to P-IW (z) proportional to E0Ndelta (z). This results in vertical profiles of epsilon (the dissipation rate of TKE) and K-h (the eddy diffusivity) according to epsilon proportional to N-delta and K-h proportional to Ndelta-2 below the main pycnocline. Earlier observations are inconclusive as to the proper value of delta, and here a range of values of delta is tested in hundreds of 10-year simulations of the southern Baltic Sea. It is concluded that delta = 1.0 +/- 0.3 and that a mean energy flux density to the internal wave field of about (0.9 +/- 0.3) x 10(-3) W m(-2) is needed to explain the observed salinity field. In addition, a simple wind-dependent formulation of the energy flux to the internal wave field is tested, which has some success in describing the short- and long-term variability of the deepwater turbulence. The model suggests that similar to16% of the energy supplied to the surface layer by the wind is used for deepwater mixing. Finally, it is also shown that Langmuir circulations are important to include when modeling the oceanic boundary layer. A simple parameterization of Langmuir circulations is tuned against large-eddy simulation data and verified for the Baltic Sea.

  • 115.
    Axell, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Liu, Ye
    SMHI, Forskningsavdelningen, Oceanografi.
    Application of 3-D ensemble variational data assimilation to a Baltic Sea reanalysis 1989-20132016Inngår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 68, artikkel-id 24220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 3-D ensemble variational (3DEnVar) data assimilation method has been implemented and tested for oceanographic data assimilation of sea surface temperature (SST), sea surface salinity (SSS), sea ice concentration (SIC), and salinity and temperature profiles. To damp spurious long-range correlations in the ensemble statistics, horizontal and vertical localisation was implemented using empirical orthogonal functions. The results show that the 3DEnVar method is indeed possible to use in oceanographic data assimilation. So far, only a seasonally dependent ensemble has been used, based on historical model simulations. Near-surface experiments showed that the ensemble statistics gave inhomogeneous and anisotropic horizontal structure functions, and assimilation of real SST and SIC fields gave smooth, realistic increment fields. The implementation was multivariate, and results showed that the cross-correlations between variables work in an intuitive way, for example, decreasing SST where SIC was increased and vice versa. The profile data assimilation also gave good results. The results from a 25-year reanalysis showed that the vertical salinity and temperature structure were significantly improved, compared to both dependent and independent data.

  • 116.
    Axell, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Ljungman, Olof
    SMHI, Forskningsavdelningen, Oceanografi.
    A One-Equation Turbulence Model for Geophysical Applications: Comparison with Data and the k - epsilon Model2001Inngår i: Environmental Fluid Mechanics, ISSN 1567-7419, E-ISSN 1573-1510, Vol. 1, nr 1, s. 71-106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A one-equation turbulence model is presented, in which the turbulent kinetic energy k is calculated with a transport equation whereas the turbulent length scale l is calculated with an algebraic expression. The value of l depends on the local stratification and reduces to the classical kappa vertical bar z vertical bar scaling for unstratified flows near a wall, where vertical bar z vertical bar is the distance to the wall. The length scale decreases during stable stratification, and increases for unstable stratification compared to the neutral case. In the limit of strong stable stratification, the so-called buoyancy length scale proportional to k(1/2)N(-1) is obtained, where N is the buoyancy frequency. The length scale formulation introduces a single model parameter which is calibrated against experimental data. The model is verified extensively against laboratory measurements and oceanic data, and comparisons are made with the two-equation k-epsilon model. It is shown that the performance of the proposed k model is almost identical to that of the k-epsilon model. In addition, the stability functions of Launder are revisited and adjusted to obtain better agreement with recent data.

  • 117. Bais, A F
    et al.
    Gardiner, B G
    Slaper, H
    Blumthaler, M
    Bernhard, G
    McKenzie, R
    Webb, A R
    Seckmeyer, G
    Kjeldstad, B
    Koskela, T
    Kirsch, P J
    Grobner, J
    Kerr, J B
    Kazadzis, S
    Leszczynski, K
    Wardle, D
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Brogniez, C
    Gillotay, D
    Reinen, H
    Weihs, P
    Svenoe, T
    Eriksen, P
    Kuik, F
    Redondas, A
    SUSPEN intercomparison of ultraviolet spectroradiometers2001Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 106, nr D12, s. 12509-12525Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Results from an intercomparison campaign of ultraviolet spectroradiometers that was organized at Nea Michaniona, Greece July, 1-13 1997, are presented. Nineteen instrument systems from 15 different countries took part and provided spectra of global solar UV irradiance for two consecutive days from sunrise to sunset every half hour. No data exchange was allowed between participants in order to achieve absolutely independent results among the instruments. The data analysis procedure included the determination of wavelength shifts and the application of suitable corrections to the measured spectra, their standardization to common spectral resolution of 1 nm full width at half maximum and the application of cosine corrections. Reference spectra were calculated for each observational time, derived for a set of instruments which were objectively selected and used as comparison norms for the assessment of the relative agreement among the various instruments. With regard to the absolute irradiance measurements, the range of the deviations from the reference for all spectra was within +/- 20%. About half of the instruments agreed to within +/-5%, while only three fell outside the +/- 10% agreement limit. As for the accuracy of the wavelength registration of the recorded spectra, for most of the spectroradiometers (14) the calculated wavelength shifts were smaller than 0.2 nm. The overall outcome of the campaign was very encouraging, as it was proven that the agreement among the majority of the instruments was good and comparable to the commonly accepted uncertainties of spectral UV measurements. In addition, many of the instruments provided consistent results relative to at least the previous two intercomparison campaigns, held in 1995 in Ispra, Italy and in 1993 in Garmisch-Partenkirchen, Germany. As a result of this series of intercomparison campaigns, several of the currently operating spectroradiometers operating may be regarded as a core group Of instruments, which with the employment of proper operational procedures are capable of providing quality spectral solar UV measurements.

  • 118. Bal, S.
    et al.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Spangehl, T.
    Cubasch, U.
    On the robustness of the solar cycle signal in the Pacific region2011Inngår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 38, artikkel-id L14809Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The potential role of the stratosphere for the 11-year solar cycle signal in the Pacific region is investigated by idealized simulations using a coupled atmosphere-ocean general circulation model. The model includes a detailed representation of the stratosphere and accounts for changes in stratospheric heating rates from prescribed time dependent variations of ozone and spectrally high resolved solar irradiance. Three transient simulations are performed spanning 21 solar cycles each. The simulations use slightly different ozone perturbations representing uncertainties of solar induced ozone variations. The model reproduces the main features of the 20th century observed solar response. A persistent mean sea level pressure response to solar forcing is found for the eastern North Pacific extending over North America. Moreover, there is evidence for a La Nina-like response assigned to solar maximum conditions with below normal SSTs in the equatorial eastern Pacific, reduced equatorial precipitation, enhanced off-equatorial precipitation and an El Nino-like response a couple of years later, thus confirming the response to solar forcing at the surface seen in earlier studies. The amplitude of the solar signal in the Pacific region depends to a great extent on the choice of the centennial period averaged. Citation: Bal, S., S. Schimanke, T. Spangehl, and U. Cubasch (2011), On the robustness of the solar cycle signal in the Pacific region, Geophys. Res. Lett., 38, L14809, doi:10.1029/2011GL047964.

  • 119. Bal, Sourabh
    et al.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Spangehl, Thomas
    Cubasch, Ulrich
    Enhanced residual mean circulation during the evolution of split type sudden stratospheric warming in observations and model simulations2018Inngår i: Proceedings of the Indian Academy of Sciences, Earth and Planetary Sciences, ISSN 0253-4126, E-ISSN 0973-774X, Vol. 127, nr 5, artikkel-id 68Artikkel i tidsskrift (Fagfellevurdert)
  • 120. Bal, Sourabh
    et al.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Spangehl, Thomas
    Cubasch, Ulrich
    Variable influence on the equatorial troposphere associated with SSW using ERA-Interim2017Inngår i: Proceedings of the Indian Academy of Sciences, Earth and Planetary Sciences, ISSN 0253-4126, E-ISSN 0973-774X, Vol. 126, nr 2, artikkel-id UNSP 19Artikkel i tidsskrift (Fagfellevurdert)
  • 121. Balaji, Venkatramani
    et al.
    Maisonnave, Eric
    Zadeh, Niki
    Lawrence, Bryan N.
    Biercamp, Joachim
    Fladrich, Uwe
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Aloisio, Giovanni
    Benson, Rusty
    Caubel, Arnaud
    Durachta, Jeffrey
    Foujols, Marie-Alice
    Lister, Grenville
    Mocavero, Silvia
    Underwood, Seth
    Wright, Garrett
    CPMIP: measurements of real computational performance of Earth system models in CMIP62017Inngår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 10, nr 1, s. 19-34Artikkel i tidsskrift (Fagfellevurdert)
  • 122. Baldacchini, Chiara
    et al.
    Castanheiro, Ana
    Maghakyan, Nairuhi
    Sgrigna, Gregorio
    Verhelst, Jolien
    Alonso, Rocio
    Amorim, Jorge Humberto
    SMHI, Forskningsavdelningen, Luftmiljö.
    Bellan, Patrick
    Bojovic, Danijela Dunisijevic
    Breuste, Juergen
    Buhler, Oliver
    Cantar, Ilie C.
    Carinanos, Paloma
    Carriero, Giulia
    Churkina, Galina
    Dinca, Lucian
    Esposito, Raffaela
    Gawronski, Stanislaw W.
    Kern, Maren
    Le Thiec, Didier
    Moretti, Marco
    Ningal, Tine
    Rantzoudi, Eleni C.
    Sinjur, Iztok
    Stojanova, Biljana
    Urosevic, Mira Anicic
    Velikova, Violeta
    Zivojinovic, Ivana
    Sahakyan, Lilit
    Calfapietra, Carlo
    Samson, Roeland
    How Does the Amount and Composition of PM Deposited on Platanus acerifolia Leaves Change Across Different Cities in Europe?2017Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, nr 3, s. 1147-1156Artikkel i tidsskrift (Fagfellevurdert)
  • 123. Baron, P.
    et al.
    Murtagh, D. P.
    Urban, J.
    Sagawa, H.
    Ochiai, S.
    Kasai, Y.
    Kikuchi, K.
    Khosrawi, F.
    Körnich, Heiner
    SMHI, Forskningsavdelningen, Meteorologi.
    Mizobuchi, S.
    Sagi, K.
    Yasui, M.
    Observation of horizontal winds in the middle-atmosphere between 30 degrees S and 55 degrees N during the northern winter 2009-20102013Inngår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 13, nr 12, s. 6049-6064Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although the links between stratospheric dynamics, climate and weather have been demonstrated, direct observations of stratospheric winds are lacking, in particular at altitudes above 30 km. We report observations of winds between 8 and 0.01 hPa (similar to 35-80 km) from October 2009 to April 2010 by the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station. The altitude range covers the region between 35-60 km where previous space-borne wind instruments show a lack of sensitivity. Both zonal and meridional wind components were obtained, though not simultaneously, in the latitude range from 30 degrees S to 55 degrees N and with a single profile precision of 7-9 ms(-1) between 8 and 0.6 hPa and better than 20 ms(-1) at altitudes above. The vertical resolution is 5-7 km except in the upper part of the retrieval range (10 km at 0.01 hPa). In the region between 1-0.05 hPa, an absolute value of the mean difference <2 ms(-1) is found between SMILES profiles retrieved from different spectroscopic lines and instrumental settings. Good agreement (absolute value of the mean difference of similar to 2 ms(-1)) is also found with the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis in most of the stratosphere except for the zonal winds over the equator (difference >5 ms(-1)). In the mesosphere, SMILES and ECMWF zonal winds exhibit large differences (>20 ms(-1)), especially in the tropics. We illustrate our results by showing daily and monthly zonal wind variations, namely the semi-annual oscillation in the tropics and reversals of the flow direction between 50-55 degrees N during sudden stratospheric warmings. The daily comparison with ECMWF winds reveals that in the beginning of February, a significantly stronger zonal westward flow is measured in the tropics at 2 hPa compared to the flow computed in the analysis (difference of similar to 20 ms(-1)). The results show that the comparison between SMILES and ECMWF winds is not only relevant for the quality assessment of the new SMILES winds, but it also provides insights on the quality of the ECMWF winds themselves. Although the instrument was not specifically designed for measuring winds, the results demonstrate that space-borne sub-mm wave radiometers have the potential to provide good quality data for improving the stratospheric winds in atmospheric models.

  • 124. Barreiro, Marcelo
    et al.
    Sitz, Lina
    de Mello, Santiago
    Fuentes Franco, Ramon
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Renom, Madeleine
    Farneti, Riccardo
    Modelling the role of Atlantic air-sea interaction in the impact of Madden-Julian Oscillation on South American climate2019Inngår i: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 39, nr 2, s. 1104-1116Artikkel i tidsskrift (Fagfellevurdert)
  • 125. Bartolino, Valerio
    et al.
    Tian, Huidong
    Bergstrom, Ulf
    Jounela, Pekka
    Aro, Eero
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Cardinale, Massimiliano
    Bland, Barbara
    Casini, Michele
    Spatio-temporal dynamics of a fish predator: Density-dependent and hydrographic effects on Baltic Sea cod population2017Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 2, artikkel-id e0172004Artikkel i tidsskrift (Fagfellevurdert)
  • 126. Bauer, Barbara
    et al.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Casini, Michele
    Hoff, Ayoe
    Margonski, Piotr
    Orio, Alessandro
    Saraiva, Sofia
    SMHI, Forskningsavdelningen, Oceanografi.
    Steenbeek, Jeroen
    Tomczak, Maciej T.
    Reducing eutrophication increases spatial extent of communities supporting commercial fisheries: a model case study2018Inngår i: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 75, nr 4, s. 1306-1317Artikkel i tidsskrift (Fagfellevurdert)
  • 127. Bauer, Barbara
    et al.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Casini, Michele
    Hoff, Ayoe
    Margonski, Piotr
    Orio, Alessandro
    Saraiva, Sofia
    SMHI, Forskningsavdelningen, Oceanografi.
    Steenbeek, Jeroen
    Tomczak, Maciej T.
    Reducing eutrophication increases spatial extent of communities supporting commercial fisheries: a model case study (vol 75, pg 1155, 2018)2018Inngår i: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 75, nr 3, s. 1155-1155Artikkel i tidsskrift (Fagfellevurdert)
  • 128. Bech, J.
    et al.
    Gjertsen, U.
    Haase, Gunther
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Modelling weather radar beam propagation and topographical blockage at northern high latitudes2007Inngår i: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 133, nr 626, s. 1191-1204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes a study to evaluate the variability of radio-propagation conditions and to assess their effects upon weather-radar beam blockage corrections for precipitation estimates. Radiosonde observations are examined in order to analyse the propagation conditions at several locations covered by the Nordic Weather Radar Network (NORDRAD). A beam-propagation model is used to simulate the interaction between the radar beam and the topography and to derive correction factors. The model is applied to correct yearly accumulations, assuming standard radio-propagation conditions, and is also used to examine case studies in detail under various propagation conditions. The correction reduces the bias between yearly radar precipitation estimates and gauge records by 1 dB for moderate blockages (1% to 50%), and by up to 3 dB for severe blockages (50% to 70%). The case studies indicate that HIRLAM forecasts show potential to predict the radar coverage and the associated ground- and sea-clutter patterns. This research aims at determining a beam-blockage-correction algorithm to be used within the NORDRAD quality-control system. This is particularly useful for obtaining radar precipitation estimates in environments with complex topography. Copyright (C) 2007 Royal Meteorological Society.

  • 129. Belda, Michal
    et al.
    Skalak, Petr
    Farda, Ales
    Halenka, Tomas
    Deque, Michel
    Csima, Gabriella
    Bartholy, Judit
    Torma, Csaba
    Boroneant, Constanta
    Caian, Mihaela
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Spiridonov, Valery
    CECILIA Regional Climate Simulations for Future Climate: Analysis of Climate Change Signal2015Inngår i: Advances in Meteorology, ISSN 1687-9309, E-ISSN 1687-9317, artikkel-id 354727Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 130. Beldring, S.
    et al.
    Andréasson, J.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    Graham, Phil
    SMHI, Affärsverksamhet.
    Jónsdóttir, J. F
    Rogozova, S.
    Rosberg, Jörgen
    SMHI, Forskningsavdelningen, Hydrologi.
    Suomalainen, M.
    Tonning, T.
    Vehviläinen, B.
    Veijalainen, N.
    Mapping water resources in the Nordic region under a changing climate.2006Rapport (Annet vitenskapelig)
  • 131. Bellucci, A.
    et al.
    Haarsma, R.
    Bellouin, N.
    Booth, B.
    Cagnazzo, C.
    van den Hurk, B.
    Keenlyside, N.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Massonnet, F.
    Materia, S.
    Weiss, M.
    Advancements in decadal climate predictability: The role of nonoceanic drivers2015Inngår i: Reviews of geophysics, ISSN 8755-1209, E-ISSN 1944-9208, Vol. 53, nr 2, s. 165-202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 132. Bellucci, A.
    et al.
    Haarsma, R.
    Gualdi, S.
    Athanasiadis, P. J.
    Caian, Mihaela
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Cassou, C.
    Fernandez, E.
    Germe, A.
    Jungclaus, J.
    Kroeger, J.
    Matei, D.
    Mueller, W.
    Pohlmann, H.
    Salas y Melia, D.
    Sanchez, E.
    Smith, D.
    Terray, L.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Yang, S.
    An assessment of a multi-model ensemble of decadal climate predictions2015Inngår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 44, nr 9-10, s. 2787-2806Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 133.
    Belusic, Danijel
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Fuentes-Franco, Ramon
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jukimenko, Alex
    Afforestation reduces cyclone intensity and precipitation extremes over Europe2019Inngår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 14, nr 7, artikkel-id UNSP 074009Artikkel i tidsskrift (Fagfellevurdert)
  • 134. Bengtsson, L.
    et al.
    Grahn, L
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Hydrological function of a thin extensive green roof in southern Sweden2005Inngår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 36, nr 3, s. 259-268Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The runoff from and the water balance of a thin extensive green roof with sedum-moss have been studied. The soil cover is about 3 cm underlain by a thin drainage layer. The water balance is determined on a monthly basis. The runoff from the green roof is much reduced compared to runoff from hard roofs because of evapotranspiration. The annual runoff is rather close to that of natural river basins. Although most rainy days there is no or little runoff from the roof, the highest observed daily runoff values are close to the daily rainfall. Runoff is initiated when the soil is at field capacity, which for the studied roof corresponds to 9 mm storage. After that, on a not very short time basis, the runoff equals the precipitation. The reduction of the daily runoff can be described in a simple way knowing the daily precipitation, potential evaporation and storage capacity of the green roof.

  • 135.
    Bengtsson,, Lennart
    et al.
    SMHI.
    Gustafsson, Nils
    SMHI, Forskningsavdelningen, Meteorologi.
    Döös, Bo
    SMHI.
    Söderman, Daniel
    Helsinki University in Finland.
    Moen, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Thompson, Thomas
    SMHI.
    Jakobsson, Paul
    SMHI.
    Bleckert, Gunnar
    SMHI.
    Henriksson, Ann-Beate
    SMHI.
    Lindgren, Bo
    SMHI.
    Kållberg, Per
    SMHI, Forskningsavdelningen, Meteorologi.
    The Meteorological Auto Code (MAC) and Numerical Weather Prediction (NWP) at SMHI2016Rapport (Annet vitenskapelig)
    Abstract [en]

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

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

  • 136.
    Bengtsson, Lisa
    et al.
    SMHI, Forskningsavdelningen, Meteorologi.
    Andrae, Ulf
    SMHI, Forskningsavdelningen, Meteorologi.
    Aspelien, Trygve
    SMHI.
    Batrak, Yurii
    Calvo, Javier
    de Rooy, Wim
    Gleeson, Emily
    Hansen-Sass, Bent
    Homleid, Mariken
    Hortal, Mariano
    Ivarsson, Karl-Ivar
    SMHI, Samhälle och säkerhet.
    Lenderink, Geert
    Niemelza, Sami
    Nielsen, Kristian Pagh
    Onvlee, Jeanette
    Rontu, Laura
    SMHI.
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Santos Munoz, Daniel
    Subias, Alvaro
    Tijm, Sander
    Toll, Velle
    Yang, Xiaohua
    Koltzow, Morten Odegaard
    The HARMONIE-AROME Model Configuration in the ALADIN-HIRLAM NWP System2017Inngår i: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 145, nr 5, s. 1919-1935Artikkel i tidsskrift (Fagfellevurdert)
  • 137.
    Bengtsson, Lisa
    et al.
    SMHI, Forskningsavdelningen, Meteorologi.
    Körnich, Heiner
    SMHI, Forskningsavdelningen, Meteorologi.
    Impact of a stochastic parametrization of cumulus convection, using cellular automata, in a mesoscale ensemble prediction system2016Inngår i: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 142, nr 695, s. 1150-1159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A stochastic parametrization for deep convection, based on cellular automata, has been evaluated in the high-resolution (2.5 km) ensemble prediction system Hirlam Aladin Regional Mesoscale Operational NWP Ensemble Prediction System (HarmonEPS). We studied whether such a stochastic physical parametrization, whilst implemented in a deterministic forecast model, can have an impact on the performance of the uncertainty estimates given by an ensemble prediction system. Various feedback mechanisms in the parametrization were studied with respect to ensemble spread and skill, in both subgrid and resolved precipitation fields. It was found that the stochastic parametrization improves the model skill in general, by reducing a positive bias in precipitation. This reduction in bias, however, led to a reduction in ensemble spread of precipitation. Overall, scores that measure the accuracy and reliability of probabilistic predictions indicate that the net impact (improved skill, degraded spread) of the ensemble prediction system is improved for 6 h accumulated precipitation with the stochastic parametrization and is rather neutral for other quantities examined.

  • 138.
    Bengtsson, Lisa
    et al.
    SMHI, Forskningsavdelningen, Meteorologi.
    Körnich, Heiner
    SMHI, Forskningsavdelningen, Meteorologi.
    Kaellen, Erland
    Svensson, Gunilla
    Large-Scale Dynamical Response to Subgrid-Scale Organization Provided by Cellular Automata2011Inngår i: Journal of Atmospheric Sciences, ISSN 0022-4928, E-ISSN 1520-0469, Vol. 68, nr 12, s. 3132-3144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Because of the limited resolution of numerical weather prediction (NWP) models, subgrid-scale physical processes are parameterized and represented by gridbox means. However, some physical processes are better represented by a mean and its variance; a typical example is deep convection, with scales varying from individual updrafts to organized mesoscale systems. This study investigates, in an idealized setting, whether a cellular automaton (CA) can be used to enhance subgrid-scale organization by forming clusters representative of the convective scales and thus yield a stochastic representation of subgrid-scale variability. The authors study the transfer of energy from the convective to the larger atmospheric scales through nonlinear wave interactions. This is done using a shallow water (SW) model initialized with equatorial wave modes. By letting a CA act on a finer resolution than that of the SW model, it can be expected to mimic the effect of, for instance, gravity wave propagation on convective organization. Employing the CA scheme permits the reproduction of the observed behavior of slowing down equatorial Kelvin modes in convectively active regions, while random perturbations fail to feed back on the large-scale flow. The analysis of kinetic energy spectra demonstrates that the CA subgrid scheme introduces energy backscatter from the smallest model scales to medium scales. However, the amount of energy backscattered depends almost solely on the memory time scale introduced to the subgrid scheme, whereas any variation in spatial scales generated does not influence the energy spectra markedly.

  • 139.
    Bengtsson, Lisa
    et al.
    SMHI, Forskningsavdelningen, Meteorologi.
    Magnusson, Linus
    Källén, Erland
    Independent Estimations of the Asymptotic Variability in an Ensemble Forecast System2008Inngår i: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 136, nr 11, s. 4105-4112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One desirable property within an ensemble forecast system is to have a one-to-one ratio between the root-mean-square error (rmse) of the ensemble mean and the standard deviation of the ensemble (spread). The ensemble spread and forecast error within the ECMWF ensemble prediction system has been extrapolated beyond 10 forecast days using a simple model for error growth. The behavior of the ensemble spread and the rmse at the time of the deterministic predictability are compared with derived relations of rmse at the infinite forecast length and the characteristic variability of the atmosphere in the limit of deterministic predictability. Utilizing this methodology suggests that the forecast model and the atmosphere do not have the same variability, which raises the question of how to obtain a perfect ensemble.

  • 140.
    Bengtsson, Lisa
    et al.
    SMHI, Forskningsavdelningen, Meteorologi.
    Steinheimer, Martin
    Bechtold, Peter
    Geleyn, Jean-Francois
    A stochastic parametrization for deep convection using cellular automata2013Inngår i: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 139, nr 675, s. 1533-1543Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A cellular automaton (CA) is introduced to the deep convection parametrization of the high-resolution limited-area model Aire Limitee Adaptation/Application de la Recherche a l'Operationnel (ALARO). The self-organizational characteristics of the CA allow for lateral communication between adjacent numerical weather prediction (NWP) model grid boxes and add additional memory to the deep convection scheme. The CA acts in two horizontal dimensions, with finer grid spacing than the NWP model. It is randomly seeded in regions where convective available potential energy (CAPE) exceeds a threshold value. Both deterministic and probabilistic rules, coupled to the large-scale wind, are explored to evolve the CA in time. Case studies indicate that the scheme has the potential to organize cells along convective squall lines and enhance advective effects. An ensemble of forecasts using the present CA scheme demonstrated an ensemble spread in the resolved wind field in regions where deep convection is large. Such a spread represents the uncertainty due to subgrid variability of deep convection and could be an interesting addition to an ensemble prediction system.

  • 141.
    Bengtsson, Lisa
    et al.
    SMHI, Forskningsavdelningen, Meteorologi.
    Tijm, Sander
    Vana, Filip
    Svensson, Gunilla
    Impact of Flow-Dependent Horizontal Diffusion on Resolved Convection in AROME2012Inngår i: Journal of Applied Meteorology and Climatology, ISSN 1558-8424, E-ISSN 1558-8432, Vol. 51, nr 1, s. 54-67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Horizontal diffusion in numerical weather prediction models is, in general, applied to reduce numerical noise at the smallest atmospheric scales. In convection-permitting models, with horizontal grid spacing on the order of 1-3 km, horizontal diffusion can improve the model skill of physical parameters such as convective precipitation. For instance, studies using the convection-permitting Applications of Research to Operations at Mesoscale model (AROME) have shown an improvement in forecasts of large precipitation amounts when horizontal diffusion is applied to falling hydrometeors. The nonphysical nature of such a procedure is undesirable, however. Within the current AROME, horizontal diffusion is imposed using linear spectral horizontal diffusion on dynamical model fields. This spectral diffusion is complemented by nonlinear, flow-dependent, horizontal diffusion applied on turbulent kinetic energy, cloud water, cloud ice, rain, snow, and graupel. In this study, nonlinear flow-dependent diffusion is applied to the dynamical model fields rather than diffusing the already predicted falling hydrometeors. In particular, the characteristics of deep convection are investigated. Results indicate that, for the same amount of diffusive damping, the maximum convective updrafts remain strong for both the current and proposed methods of horizontal diffusion. Diffusing the falling hydrometeors is necessary to see a reduction in rain intensity, but a more physically justified solution can be obtained by increasing the amount of damping on the smallest atmospheric scales using the nonlinear, flow-dependent, diffusion scheme. In doing so, a reduction in vertical velocity was found, resulting in a reduction in maximum rain intensity.

  • 142. Bennartz, R
    et al.
    Thoss, Anke
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Dybbroe, Adam
    SMHI, Samhälle och säkerhet.
    Michelson, Daniel
    SMHI, Samhälle och säkerhet.
    Precipitation analysis using the Advanced Microwave Sounding Unit in support of nowcasting applications2002Inngår i: Meteorological Applications, ISSN 1350-4827, E-ISSN 1469-8080, Vol. 9, nr 2, s. 177-189Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We describe a method to remotely sense precipitation and classify its intensity over water, coasts and land surfaces. This method is intended to be used in an operational nowcasting environment. It is based on data obtained from the Advanced Microwave Sounding Unit (AMSU) onboard NOAA-15. Each observation is assigned a probability of belonging to four classes: precipitation-free, risk of precipitation, precipitation between 0.5 and 5 mm/h, and precipitation higher than 5 mm/h. Since the method is designed to work over different surface types, it relies mainly on the scattering signal of precipitation-sized ice particles received at high frequencies. For the calibration and validation of the method we use an eight-month dataset of combined weather radar and AMSU data obtained over the Baltic area. We compare results for the AMSU-B channels at 89 GHz and 150 GHz and find that the high frequency channel at 150 GHz allows for a much better discrimination of different types of precipitation than the 89 GHz channel. While precipitation-free areas, as well as heavily precipitating areas (> 5 mm/h), can be identified to high accuracy, the intermediate classes are more ambiguous. This stems from the ambiguity of the passive microwave observations as well as from the non-perfect matching of the different data sources and sub-optimal radar adjustment. In addition to a statistical assessment of the method's accuracy, we present case studies to demonstrate its capabilities to classify different types of precipitation and to work over highly structured, inhomogeneous surfaces.

  • 143. Bennartz, Ralf
    et al.
    Hoschen, Heidrun
    Picard, Bruno
    Schroder, Marc
    Stengel, Martin
    Sus, Oliver
    Bojkov, Bojan
    Casadio, Stefano
    Diedrich, Hannes
    Eliasson, Salomon
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Fell, Frank
    Fischer, Jurgen
    Hollmann, Rainer
    Preusker, Rene
    Willén, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    An intercalibrated dataset of total column water vapour and wet tropospheric correction based on MWR on board ERS-1, ERS-2, and Envisat2017Inngår i: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 10, nr 4, s. 1387-1402Artikkel i tidsskrift (Fagfellevurdert)
  • 144.
    Bennartz, Ralf
    et al.
    SMHI.
    Thoss, Anke
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Dybbroe, Adam
    SMHI, Samhälle och säkerhet.
    Michelson, Daniel
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Precipitation Analysis from AMSU (Nowcasting SAF)1999Rapport (Annet vitenskapelig)
  • 145.
    Bennet, Cecilia
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Engardt, Magnuz
    SMHI, Forskningsavdelningen, Luftmiljö.
    A regional model for surface ozone in Southeast Asia2008Inngår i: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 60, nr 5, s. 718-728Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As part of the model intercomparison study MICS Asia II, the Swedish MATCH model was set up for Southeast and East Asia. In that study, the comprehensive photochemistry scheme of MATCH was used for the first time in Asia. The current work focuses on results of surface ozone from the MATCH model simulations falling outside the model intercomparison study. Model results of surface ozone concentrations for the entire year of 2001 were investigated and compared with measurements in Southeast Asia. The model produced higher surface ozone concentrations than the observations at all of the non-remote stations investigated but underestimated during the dry season at remote locations. Modelled seasonal variation was similar to, but less pronounced than, the variation in the measurements. This study indicates that NO(x) is the limiting precursor for ozone production in the model, while the fractionation in different species and total amount of non-methane volatile organic compounds (NMVOC) emissions are less important. Naturally emitted NMVOC, isoprene, is an important precursor of surface ozone at certain conditions, and a better inventory of these emissions is needed. Deposition velocities of ozone also have impact on surface concentrations. To improve the model performance, it is important to add a land use inventory with corresponding deposition velocities.

  • 146.
    Bennet, Cecilia
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Jonsson, P
    Lindgren, E S
    Concentrations and sources of trace elements in particulate air pollution, Dar es Salaam, Tanzania, studied by EDXRF2005Inngår i: X-Ray Spectrometry, ISSN 0049-8246, E-ISSN 1097-4539, Vol. 34, nr 1, s. 1-6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Trace elements in near-ground atmospheric aerosols were investigated in Dar es Salaam, Tanzania. Particles were collected at two sites, one urban and one rural, during, two months with different meteorological conditions. The samplers, dichotomous impactors, segregate the particles into two size fractions, fine (PM2.5, d(a) < 2.5 mum) and coarse (2.5 < d(a) < 10 mum). A sharp cyclone was used to sample finer particles (PM1, d(a) < 1 mum). Meteorological parameters were also examined at both sites. An EDXRF spectrometer, based on three-axial geometry, was used for quantitative elemental analysis. Concentrations of elements heavier than phosphorus were determined. Also, the content of black carbon on the filters was measured with a reflectometer. The elemental concentrations were compared with respect to season and geographical location in the city. The levels of different species in Dar es Salaam were also compared with similar data from other African and European countries. This showed low values of Pb with respect to the size of the city and no legislation on the use of leaded petrol, that often is the main source of lead. High values of Cl were also found, as would be expected in a coastal city. The coarse particles in the air, originating from soil, had a different composition in Dar es Salaam than in Gaborone, Botswana, and the concentration of black carbon was higher than in other cities. On the basis of the data collected, source assignments were made and the following sources found; sea-spray, soil, city road dust, biomass burning industries and traffic. Comparing the concentrations of different elements in PM2.5 and PM1 revealed that black carbon, Zn, Pb, K and Br are present only in the smallest particles. Copyright (C) 2005 John Wiley Sons, Ltd.

  • 147. Berdalet, Elisa
    et al.
    Kudela, Raphael
    Urban, Ed
    Enevoldsen, Henrik
    Banas, Neil S.
    Bresnan, Eileen
    Burford, Michele
    Davidson, Keith
    Gobler, Christopher J.
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Lim, Po Teen
    Mackenzie, Lincoln
    Montresor, Marina
    Trainer, Vera L.
    Usup, Gires
    Yin, Kedong
    GlobalHAB A New Program to Promote International Research, Observations, and Modeling of Harmful Algal Blooms in Aquatic Systems2017Inngår i: Oceanography, ISSN 1042-8275, Vol. 30, nr 1, s. 70-81Artikkel i tidsskrift (Fagfellevurdert)
  • 148.
    Berg, Peter
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Bosshard, Thomas
    SMHI, Forskningsavdelningen, Hydrologi.
    Yang, Wei
    SMHI, Forskningsavdelningen, Hydrologi.
    Model Consistent Pseudo-Observations of Precipitation and Their Use for Bias Correcting Regional Climate Models2015Inngår i: CLIMATE, ISSN 2225-1154, Vol. 3, nr 1, s. 118-132Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lack of suitable observational data makes bias correction of high space and time resolution regional climate models (RCM) problematic. We present a method to construct pseudo-observational precipitation data by merging a large scale constrained RCM reanalysis downscaling simulation with coarse time and space resolution observations. The large scale constraint synchronizes the inner domain solution to the driving reanalysis model, such that the simulated weather is similar to observations on a monthly time scale. Monthly biases for each single month are corrected to the corresponding month of the observational data, and applied to the finer temporal resolution of the RCM. A low-pass filter is applied to the correction factors to retain the small spatial scale information of the RCM. The method is applied to a 12.5 km RCM simulation and proven successful in producing a reliable pseudo-observational data set. Furthermore, the constructed data set is applied as reference in a quantile mapping bias correction, and is proven skillful in retaining small scale information of the RCM, while still correcting the large scale spatial bias. The proposed method allows bias correction of high resolution model simulations without changing the fine scale spatial features, i.e., retaining the very information required by many impact models.

  • 149.
    Berg, Peter
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Christensen, Ole B.
    Klehmet, Katharina
    SMHI, Forskningsavdelningen, Hydrologi.
    Lenderink, Geert
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Teichmann, Claas
    Yang, Wei
    SMHI, Forskningsavdelningen, Hydrologi.
    Summertime precipitation extremes in a EURO-CORDEX 0.11 degrees ensemble at an hourly resolution2019Inngår i: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 19, nr 4, s. 957-971Artikkel i tidsskrift (Fagfellevurdert)
  • 150.
    Berg, Peter
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Koenigk, Torben
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Impacts of using spectral nudging on regional climate model RCA4 simulations of the Arctic2013Inngår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 6, nr 3, s. 849-859Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

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