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  • 1. Achberger, C
    et al.
    Chen, D L
    Alexandersson, Hans
    SMHI.
    The surface winds of Sweden during 1999-20002006Ingår i: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 26, nr 2, s. 159-178Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study aims at increasing our understanding of the regional wind climate in Sweden. Spatial and temporal patterns of the surface winds are presented for the years 1999-2000. Annual mean wind speeds range between 2 and 5 m/s with high values at exposed mountainous sites and on islands off the coast. Combining wind speed and direction into mean wind velocities shows that flow conditions are stronger and more coherent in space in southern Sweden than in central and northern Sweden. The spatial scale, defined as the distance between stations when the correlation for wind speed drops to similar to 0.37, was determined by pairwise correlations between all possible station pairs. Scales range from 38 to 530 km for wind speed and from 40 to 830 km for wind direction depending on the region. They tend to be smaller in central and northern Sweden, where the more pronounced relief has a larger influence on the local wind conditions. The strength and the timing of the annual and diurnal wind speed cycle have been estimated for each station. Amplitudes of the annual cycle are greater at exposed sites and correlate generally well with annual mean wind speeds. Monthly mean wind speeds peak in winter in southern Sweden, but peak in other seasons in the remaining regions. In winter, weaker pressure gradients over northern Sweden and surface-near temperature inversions contribute to weaker surface winds. Diurnal cycles vary in strength between summer and winter. Compared to the last normal climate period (1961-1990), 1999-2000 is characterized by the increased occurrence of westerly and southerly geostrophic flow. Copyright (C) 2005 Royal Meteorological Society.

  • 2.
    Ahlström, Bengt
    et al.
    SMHI.
    Salomonsson, Gösta
    SMHI.
    Resultat av 5-dygnsprognos till ledning för isbrytarverksamhet vintern 1984–851985Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Temperaturprognoserna och vindprognoserna för pentad 1-5 har haft hög träffprocent. Medelvärdet 83.3 för pentadtemperaturen är det näst bästa under den senaste 10-årsperioden, och värdet 74.0 för vindprognoserna det tredje bästa. Intrycket av en förbättring av prognoskvalitén from säsongen 1978/79, vilket framhölls i föregående års rapport, befästs av 1984/85 års resultat. När det gäller temperaturprognoserna för pentad 6-10 kan man däremot inte se någon nämnvärd förbättring.

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  • 3.
    Akinde, Michael
    et al.
    SMHI.
    Bohlen, M H
    Johnson, T
    Lakshmanan, L V S
    Srivastava, D
    Efficient OLAP query processing in distributed data warehouses2003Ingår i: Information Systems, ISSN 0306-4379, E-ISSN 1873-6076, Vol. 28, nr 1-2, s. 111-135Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The success of Internet applications has led to an explosive growth in the demand for bandwidth from. Internet Service Providers. Managing an Internet protocol network requires collecting and analyzing network data, such as flow-level traffic statistics. Such analyses can typically be expressed as OLAP queries, e.g., correlated aggregate queries and data cubes. Current day OLAP tools for this task assume the availability of the data in a centralized data warehouse. However, the inherently distributed nature of data collection and the huge amount of data extracted at each collection point make it impractical to gather all data at a centralized site. One solution is to maintain a distributed data warehouse, consisting of local data warehouses at-each collection point and a coordinator site, with most of the processing being performed at the local sites. In this paper, we consider the problem of efficient evaluation of OLAP queries over a distributed data warehouse. We have developed the Skalla system for this task. Skalla translates OLAP queries, specified as certain algebraic expressions, into distributed evaluation plans which are shipped to individual sites. A salient property of our approach is that only partial results are shipped - never parts of the detail data. We propose a variety of optimizations to minimize both the synchronization traffic and the local processing done at each site. We finally present an experimental study based on TPC-R data. Our results demonstrate the scalability of our techniques and quantify the performance benefits of the optimization techniques that have gone into the Skalla system. (C) 2002 Elsevier Science Ltd. All rights reserved.

  • 4. Alberoni, P P
    et al.
    Andersson, T
    SMHI.
    Mezzasalma, P
    Michelson, Daniel
    SMHI, Samhälle och säkerhet.
    Nanni, S
    Use of the vertical reflectivity profile for identification of anomalous propagation2001Ingår i: Meteorological Applications, ISSN 1350-4827, E-ISSN 1469-8080, Vol. 8, nr 3, s. 257-266Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anomalous propagation (anaprop), analogous to the upper mirage in the visual wavelengths, is still a major problem in radar meteorology. This phenomenon assumes particular importance in automatic recognition and estimation of rainfall. Anaprop echoes from terrain features such as hills and coasts Often give echoes up to 50-60 dBZ equivalent to heavy rain or hail in severe thunderstorms. Anaprop echoes from sea waves may be comparable in strength to those from moderate precipitation and also form similar patterns. Based on the evidence that the vertical reflectivity profile of precipitation is quite different from the anaprop profile, two methods for anaprop identification are presented. The method proposed by the Servizio Meteorologico Regionale (SMR, Italy) simply uses the operational scan procedure to discriminate between precipitation and anaprop. At the Swedish Meteorological and Hydrological Institute an 'ad hoc' scan strategy has been developed in order to obtain much more detail of the lowest reflectivity profile. A number of statistical parameters have been used to achieve a better discrimination between precipitation, land and sea clutter. A number of case studies, representing different echo intensities and patterns, and including a case of anaprop with embedded precipitation, are presented to assess the impact of these methods.

  • 5.
    Alexandersson, Hans
    SMHI.
    Temperatur och nederbörd i Sverige 1860 -20012002Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Swedish temperature and precipitation series from 1860-2001 are analysed  in this report. Sweden  is divided into four regions. These are defined according to the drainage basins: Gulf of Bothnia (Bv), Bothnian Sea (Bh), Proper Baltic Sea (EÖ) and Kattegatt and Skagerrak (Vh). Annual series of  temperature and precipitation as well as series for the traditional  seasons  winter (December  previous year, January, February), spring (March, April, May), summer (June, July, August) and autumn (Sep­ tember, October, November) are presented. All series have been homgenised and all missing values for incomplete series have been filled out by    interpolation.

     

    Generally the analyses show that Sweden has become warmer  and wetter  in this centennial  perspective.  As a rule changes and trends are larger in the two northerly regions (Bv and Bh). The increase of annual temperature amounts to 0.9° (Bv), 0.8° (Bh), 0.5° (EÖ) and 0.5° (Vh) when data from the colder period 1860-1925 is compared with the warmer period 1926-2001. Annual precipitation <luring the drier period 1860-1920  is compared  with the wetter  period  1921-2001. The  relative changes  are 23% (Bv), 15% (Bh), 7% (EÖ) and 7% (Vh). Spring temperature  and winter precipitation  show especially !arge    mcreases.

     

    Comparisons with runoff data indicate that evapotranspiration has become much larger. It is argued that the substantial increase of forest biomass could be one explanation and higher temperatures could be another. The increase of forest biomass leads to larger interception and then larger evaporation and as a rule also larger transpiration. The warming in spring and autumn leads to a longer active season for the vegetation.

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  • 6.
    Alexandersson, Hans
    et al.
    SMHI.
    Dahlström, Bengt
    SMHI, Samhälle och säkerhet.
    Future climate in the Nordic region – survey and synthesis for the next century1992Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The greenhouse gases carbon dioxide, methane, chlorfluorcarbons and nitrous  oxide are increasing due to man's activities. 0n physical grounds it is generally believed that this will influence the climate of the earth. Observational evidence, mainly global mean temperatures, indicate that the earth becomes warmer at present. It is, however, not possible to rule out that natura! factors have caused observed changes until now. Swedish data show small or no trends at present.

    The suggested scenarios for Sweden are given in interval form to express the large uncertainty. For temperature and precipitation in the years around 2030 we suggest the following changes compared with the levels around 1990.

                     Winter   Summer Winter     Summer.            

                     temp.    temp.     Prec.       Prec.

    Northern

    Sweden:    0.5-1.5  00-1.5     0-15 %   0-10 %

    Southern

    Sweden:    0.0-1.0  0.0-0.5    0-15 %   0-10 %

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  • 7.
    Alexandersson, Hans
    et al.
    SMHI.
    Eggertsson Karlström, Carla
    SMHI.
    Larsson-McCann, Sonja
    SMHI, Affärsverksamhet.
    Temperaturen och nederbörden i Sverige 1961-90: Referensnormaler1991Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Mean values of temperature and precipitation are presented in this report. Reference normals for the period 1961-90 have been calculated for 510 stations with temperature measurements and for 1243 stations with precipitation measurements. These values, monthly and annual, will be used in comparison with measured actual values.

    The report also contains maps, for every month and for the year, showing the differences for temperature and ratios for precipitation between the reference values for the periods 1961-90 and 1931-60. Two other maps show mean monthly reference temperatures for January and July respectively. Another two maps show the average annual number of days with 1 mm or more and the average annual precipitation.

    In the end of the report there is a list of all the stations with reference values and a map containing all the stations that also were operating the first of januari 1991.

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  • 8.
    Alexandersson, Hans
    et al.
    SMHI.
    Eggertsson Karlström, Carla
    SMHI.
    Laurin, Sten
    SMHI.
    Några huvuddrag i det svenska nederbördsklimatet 1961-19901997Rapport (Övrigt vetenskapligt)
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  • 9.
    Alexandersson, Hans
    et al.
    SMHI.
    Eriksson, Bertil
    SMHI.
    Climate fluctuations in Sweden 1860–19871989Rapport (Övrigt vetenskapligt)
    Abstract [en]

    We are living in a time when there is a great concern and anxiety on climate changes, induced by man or natural. Figures showing trends or abrupt changes may not seldom be based on rather poor climate records. Thus we have started a climate project at SMHI where we have taken great care to avoid non- homogeneous records and where we have limited our aims to the period of instrumental records (mainly from 1860 in Sweden but a few stations have data from about 1750). Three elements have been studied extensively: temperature, precipitation and air pressure. Two main areas within Sweden were selected. In order to avoid non- homogeneous data the temporal analysis was preceded by a spatial homogeneity test which revealed several discontinuities and artificial trends. Long- term fluctuations were visualized by using a Gaussian low pass filter. One interesting feature is that the pressure difference northern to southern Sweden showed a decrease by about 10% around 1930. The corresponding decrease of the zonal wind may to some extent explain the quite large frequency of cold winters in later decades as high winter temperatures in Scandinavia is strongly connected with westerly and southwesterly inflow of mild and humid Atlantic air-masses. Another interesting but still somewhat questionable feature is the dry early decades.

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  • 10.
    Alexandersson, Hans
    et al.
    SMHI.
    Gollvik, Stefan
    Meterologi.
    Meuller, Lars
    SMHI.
    An energy balance model for prediction of surface temperatures1991Rapport (Övrigt vetenskapligt)
    Abstract [en]

    From the winter season 1988/89 and onwards an energy balance model has been used to estimate surface temperatures within a weather seivice system for the road authorities in "Östergötlands" and "Göteborg-Bohuslän" in Sweden. It is based on a simplified form of the energy balance equation at the surface and a numerical model with ten layers in the ground or road. In the road seivice system manually given forecasts of clouds and wind are used as input into the model. The initial values of surface temperatures are obtained on-line from the road stations involved. Forecasts of surface temperatures have been made for up to five hours and give significantly better results than e.g. perstistency or linear trend forecasts.

    The model has also been generalized to run directly on model output clouds an winds and to give forecasts for a large area. As starting values we then use screen temperatures analysed in a grid net with a resolution of about 20 km covering Scandinavia. Initial surface temperatures are obtained through extrapolation to the ground. Through a relaxation formula forecasted surface temperatures are then transformed back to screen level. The temperature forecasts obtained in this way seem to be much better than the LAM-model gives where the daily amplitude is too small.

    This latter model is henceforth called the objective system while the former is called the road seivice system. The two aystems have large parts in common. Differing parts are indicated in section headings ant text.

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  • 11. Alfredsson, L.
    et al.
    Segersson, David
    SMHI, Forskningsavdelningen, Meteorologi.
    Hillert, J.
    Kockum, I.
    Strid, P.
    Olsson, T.
    Bellander, T.
    Hedstrom, A. K.
    Association Between Exposure to Combustion-Related Air Pollution and Multiple Sclerosis Risk2023Ingår i: Multiple Sclerosis Journal, ISSN 1352-4585, E-ISSN 1477-0970, Vol. 29, s. 99-99Artikel i tidskrift (Refereegranskat)
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    Association between exposure to combustion-related air pollution and multiple sclerosis risk
  • 12.
    Alpfjord Wylde, Helene
    et al.
    SMHI, Affärsverksamhet.
    Asker, Christian
    SMHI, Forskningsavdelningen, Meteorologi.
    Bennet, Cecilia
    SMHI, Forskningsavdelningen, Meteorologi.
    Segersson, David
    SMHI, Forskningsavdelningen, Meteorologi.
    Quantification of population exposure to PM10, PM2.5 and NO2 and estimated health impacts for 2019 and 20302023Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Halter av NO2, PM10 och PM2.5 har beräknats för hela Sverige för år 2019 och för två scenarier 2030 i den här studien. Beräkningar har gjorts med en ny metodik som möjliggör en nästan helt sömlös kombination av spridningsmodellering på regional och urban skala utan att dubbelräkna emissioner. Föroreningshalter har beräknats på 250x250 m2 upplösning, vilket ger ett unikt komplett och detaljerat dataset på nationell skala. Metodiken kan väl reproducera uppmätta föroreningshalter vid de flesta urbana bakgrundsstationerna i modelldomänet. Den spatiala upplösningen på 250 m fångar koncentrationsgradienter av vikt för exponeringsberäkningar. En styrka med att använda spridningsmodeller för att beräkna föroreningshalter är den direkta kopplingen till emissionsinventeringar och projektioner.

    Modellerade föroreningshalter kombineras med griddad befolkningsdata för att beräkna exponering. Den befolkningsviktade årsmedelexponeringen är 5,08 μg/m3 för NO2, 9,95 μg/m3 för PM10 och 5,21 μg/m3 för PM2.5 år 2019. En stor minskning, med cirka 2 μg/m3till 2030, beräknas för exponering av NO2. Exponeringen för PM10 och PM2.5 minskar också till 2030, men inte lika drastiskt, med ungefär 0,2 μg/m3.

    En generell slutsats är att exponeringen är högre i åldersspannet 21-50 år. En förklaring är dessa åldersgrupper oftare bor i urbana områden, med mer utsläpp och högre föroreningshalter.

    Noll procent av befolkningen exponeras för halter över den årliga miljökvalitetsnormen för NO2, PM10 och PM2.5, varken år 2019 eller 2030. Det ska dock noteras att modellresultaten representerar årsmedelvärden av urbana bakgrundskoncentrationer, inte lokala hotspots.

    De modellbaserade beräkningarna av exponeringen för PM2.5 och lokalt genererad NO2 har använts i en nationell hälsokonsekvensberäkning. Hälsokonsekvensberäkningen liknar en nyligen publicerad beräkning avseende 2019, av förtida dödsfall och uppkomst av främst kroniska sjukdomar. Våra resultat avviker i olika riktning från resultaten i liknande beräkningar. En avgörande och komplicerad anledning till skillnader i de beräknade hälsokonsekvenserna är vilka exponerings-responssamband för specifika föroreningar som man baserar sina beräkningar på, riskkurvans form och om det finns någon säker nivå under vilken sambandet upphör. I denna studie har vi valt att luta oss mot den vetenskapliga evidens som ges av högkvalitativa epidemiologiska studier för att sambanden mellan partikelhalt och dödlighet är supra-linjära med den brantaste riskökningen vid de lägsta halterna, att effekterna är starkare nära källan samt att det inte finns stöd för någon tröskelnivå under vilken halten saknar betydelse. När vi räknar ihop antal förtida dödsfall per år som den regionala bakgrundshalten av PM2.5 beräknas orsaka med de dödsfall som beräknas uppkomma till följd av partikelutsläpp på hemorten så blir summan 4 264 förtida dödsfall relaterade till föroreningssituationen 2019. För samma exponeringssituation uppskattar vi att de lokalt genererade bidragettill NO2-halten leder till ytterligare 428 förtida dödsfall per år.

    2030 beräknas befolkningsexponeringen för PM2.5 från den regionala bakgrunden ha minskat med omkring 2 % och från urbana källor med 22 % jämfört med 2019, vilket indikerar hur mycket antalet förtida dödsfall skulle reduceras om allt övrigt är oförändrat.

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    Quantification of population exposure to PM10, PM2.5 and NO2 and estimated health impacts for 2019 and 2030
  • 13.
    Amorim, Jorge Humberto
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Segersson, David
    SMHI, Forskningsavdelningen, Luftmiljö.
    Körnich, Heiner
    SMHI, Forskningsavdelningen, Meteorologi.
    Asker, Christian
    SMHI, Forskningsavdelningen, Luftmiljö.
    Olsson, Esbjörn
    SMHI, Forskningsavdelningen, Meteorologi.
    Gidhagen, Lars
    SMHI, Forskningsavdelningen, Luftmiljö.
    High resolution simulation of Stockholm's air temperature and its interactions with urban development2020Ingår i: Urban Climate, E-ISSN 2212-0955, Vol. 32, artikel-id 100632Artikel i tidskrift (Refereegranskat)
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  • 14.
    Andersson, Camilla
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Alpfjord Wylde, Helene
    SMHI, Affärsverksamhet.
    Engardt, Magnuz
    SMHI, Forskningsavdelningen, Luftmiljö.
    Long-term sulfur and nitrogen deposition in Sweden: 1983-2013 reanalysis2018Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Ett unikt långt dataset (1983-2013) för svavel- och kvävedeposition har skapats för Sverige samt Östersjön och omgivande länder. Det baseras på kvalitetsgranskade mätningar och modellfält, kombinerade genom avancerade metoder för att fånga spatiala och temporala variationer. Datasetet kan användas för att beskriva trender i deposition till olika relevanta marktyper.Återanalysen stämmer väl överens med mätningar, men vi har identifierat skillnader i torrdeposition till barrskog. Detta visar på behov av djupare studier och metodikförbättringar för bestämning av torrdeposition.Vi rekommenderar mer avancerade metoder för att beskriva spatial variation än genom medelvärdesbildning eller spatial interpolering av uppmätt deposition.Vi finner en markant minskning från 1980-talet fram till idag för både svavel- och kvävedeposition (med cirka 80 % respektive 30 %).Kritiska belastningar till både barr- och lövskog, fjällmarker och våtmarker har överskridits framförallt i sydvästra Sverige, men också i sydöstra Sverige och södra fjällen. Situationen förbättras men överskridanden sker fortfarande även över större områden.

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  • 15.
    Andersson, Camilla
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Engardt, Magnuz
    SMHI, Forskningsavdelningen, Luftmiljö.
    European ozone in a future climate: Importance of changes in dry deposition and isoprene emissions2010Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 115, artikel-id D02303Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Projections of future surface ozone over Europe conducted utilizing chemistry transport models (CTMs) coupled to climate models differ greatly, even in sign. CTM sensitivity studies were conducted in order to investigate the importance of changes in natural isoprene emissions and dry deposition to vegetation, both coupled to meteorology. This knowledge can be used to improve surface ozone projections. Our simulations suggest climate change over Europe would cause changes in surface ozone between -4.0 to +13 ppb(v) on average (April-September) and -3.5 to +25 ppb(v) on average (April-September) daily maximum from 1961 - 1990 to 2071 - 2100. The change is positive in the southwest and negative in the north. The isoprene emissions increased by a factor of about 1.8 from 1961 - 1990 to 2071 - 2100. A rescaling of isoprene emissions shows that the large increase in isoprene emission is of importance (0 - 30% of the change in surface ozone) in central, southern, and western Europe. The use of a formulation for ozone dry deposition to vegetation, dependent on meteorology, and changes in snow cover, affecting the dry deposition, are more important processes. The changes in dry deposition to vegetation (not including changes in aerodynamic resistance) explain up to 80% of the surface ozone change in Spain. Therefore it is vital to include meteorological dependence for dry deposition of ozone to vegetation in surface ozone projections. Isoprene emissions are of less importance, but they are nonnegligible and should definitely be emitted online in climate ozone projection studies.

  • 16.
    Andersson, Camilla
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Langner, Joakim
    SMHI, Forskningsavdelningen, Luftmiljö.
    Bergström, Robert
    SMHI, Forskningsavdelningen, Luftmiljö.
    Interannual variation and trends in air pollution over Europe due to climate variability during 1958-2001 simulated with a regional CTM coupled to the ERA40 reanalysis2007Ingår i: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 59, nr 1, s. 77-98Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A three-dimensional Chemistry Transport Model was used to study the meteorologically induced interannual variability and trends in deposition of sulphur and nitrogen as well as concentrations of surface ozone (O(3)), nitrogen dioxide (NO(2)) and particulate matter (PM) and its constituents over Europe during 1958-2001. The model was coupled to the meteorological reanalysis ERA40, produced at the European Centre for Medium-range Weather Forecasts. Emissions and boundary conditions of chemical compounds and PM were kept constant at present levels. The average European interannual variation, due to meteorological variability, ranges from 3% for O(3), 5% for NO(2), 9% for PM, 6-9% for dry deposition, to about 20% for wet deposition of sulphur and nitrogen. For the period 1979-2001 the trend in ozone, due to climate variability is increasing in central and southwestern Europe and decreasing in northeastern Europe, the trend in NO(2) is approximately opposite. The trend in PM is positive in eastern Europe. There are negative trends in wet deposition in southwestern and central Europe and positive trends in dry deposition overall. A bias in ERA40 precipitation could be partly responsible for the trends. The variation and trends need to be considered when interpreting measurements and designing measurement campaigns.

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  • 17. Andersson, E.
    et al.
    Kahnert, Michael
    SMHI, Forskningsavdelningen, Luftmiljö.
    Devasthale, Abhay
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Methodology for evaluating lateral boundary conditions in the regional chemical transport model MATCH (v5.5.0) using combined satellite and ground-based observations2015Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 8, nr 11, s. 3747-3763Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hemispheric transport of air pollutants can have a significant impact on regional air quality, as well as on the effect of air pollutants on regional climate. An accurate representation of hemispheric transport in regional chemical transport models (CTMs) depends on the specification of the lateral boundary conditions (LBCs). This study focuses on the methodology for evaluating LBCs of two moderately long-lived trace gases, carbon monoxide (CO) and ozone (O-3), for the European model domain and over a 7-year period, 2006-2012. The method is based on combining the use of satellite observations at the lateral boundary with the use of both satellite and in situ ground observations within the model domain. The LBCs are generated by the global European Monitoring and Evaluation Programme Meteorological Synthesizing Centre - West (EMEP MSC-W) model; they are evaluated at the lateral boundaries by comparison with satellite observations of the Terra-MOPITT (Measurements Of Pollution In The Troposphere) sensor (CO) and the Aura-OMI (Ozone Monitoring Instrument) sensor (O-3). The LBCs from the global model lie well within the satellite uncertainties for both CO and O-3. The biases increase below 700 hPa for both species. However, the satellite retrievals below this height are strongly influenced by the a priori data; hence, they are less reliable than at, e.g. 500 hPa. CO is, on average, underestimated by the global model, while O-3 tends to be overestimated during winter, and underestimated during summer. A regional CTM is run with (a) the validated monthly climatological LBCs from the global model; (b) dynamical LBCs from the global model; and (c) constant LBCs based on in situ ground observations near the domain boundary. The results are validated against independent satellite retrievals from the Aqua-AIRS (Atmospheric InfraRed Sounder) sensor at 500 hPa, and against in situ ground observations from the Global Atmospheric Watch (GAW) network. It is found that (i) the use of LBCs from the global model gives reliable in-domain results for O-3 and CO at 500 hPa. Taking AIRS retrievals as a reference, the use of these LBCs substantially improves spatial pattern correlations in the free troposphere as compared to results obtained with fixed LBCs based on ground observations. Also, the magnitude of the bias is reduced by the new LBCs for both trace gases. This demonstrates that the validation methodology based on using satellite observations at the domain boundary is sufficiently robust in the free troposphere. (ii) The impact of the LBCs on ground concentrations is significant only at locations in close proximity to the domain boundary. As the satellite data near the ground mainly reflect the a priori estimate used in the retrieval procedure, they are of little use for evaluating the effect of LBCs on ground concentrations. Rather, the evaluation of ground-level concentrations needs to rely on in situ ground observations. (iii) The improvements of dynamic over climatological LBCs become most apparent when using accumulated ozone over threshold 40 ppb (AOT40) as a metric. Also, when focusing on ground observations taken near the inflow boundary of the model domain, one finds that the use of dynamical LBCs yields a more accurate representation of the seasonal variation, as well as of the variability of the trace gas concentrations on shorter timescales.

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  • 18. Andersson, Eva M.
    et al.
    Ogren, Mikael
    Molnar, Peter
    Segersson, David
    SMHI, Forskningsavdelningen, Luftmiljö.
    Rosengren, Annika
    Stockfelt, Leo
    Road traffic noise, air pollution and cardiovascular events in a Swedish cohort2020Ingår i: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 185, artikel-id 109446Artikel i tidskrift (Refereegranskat)
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  • 19. Andersson, John
    et al.
    Sundstrom, Anna
    Nordin, Maria
    Segersson, David
    SMHI, Forskningsavdelningen, Meteorologi.
    Forsberg, Bertil
    Adolfsson, Rolf
    Oudin, Anna
    PM2.5 and Dementia in a Low Exposure Setting: The Influence of Odor Identification Ability and APOE2023Ingår i: Journal of Alzheimer's Disease, ISSN 1387-2877, E-ISSN 1875-8908, Vol. 92, nr 2, s. 679-689Artikel i tidskrift (Refereegranskat)
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  • 20.
    Andersson, Stefan
    et al.
    SMHI, Affärsverksamhet.
    Arvelius, Johan
    SMHI, Affärsverksamhet.
    Jones, Jörgen
    SMHI, Affärsverksamhet.
    Kindell, Sven
    SMHI, Affärsverksamhet.
    Leung, Wing
    SMHI, Affärsverksamhet.
    Beräkningar av emissioner och halter avbenso(a)pyren och partiklar frånsmåskalig vedeldning: Luftkvalitetsmodellering för Skellefteå, Strömsunds och Alingsås kommuner2019Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    I denna studie har emissioner och halter i utomhusluften av benso(a)pyren (B(a)P) samt partiklar (PM2.5) beräknats för Skellefteå, Strömsunds och Alingsås kommuner avseende småskalig uppvärmning. Emissioner har beräknats för hela kommunerna, medan luftkvalitet har modellerats för två tätorter i varje kommun; Boliden och Bureå i Skellefteå kommun, Backe och Hoting i Strömsunds kommun samt Alingsås och Sollebrunn i Alingsås kommun. De tre kommunerna valdes då de identifierades ha höga B(a)P-halter i den tidigare nationella B(a)P-kartläggningen samt tillgång till sotarregister av tillräcklig bra kvalitet; tätorterna valdes genom att analysera emissionsberäkningarna i varje kommun och välja ut tätorter med de högsta emissionerna.

    Syftet med studien är undersöka hur B(a)P- och PM2.5-halterna i Sverige förhåller sig till miljökvalitetsnormer, utvärderingströsklar samt preciseringen av miljökvalitetsmålet Frisk luft och analysera hur stort gapet är för att klara dessa. Detta genom spridningsmodellering samt utvärdering mot mätningar i fem av tätorterna. Osäkerheterna i den tidigare gjorda nationella karteringen av B(a)Phalter från småskalig vedeldning (Andersson et al., 2015), som ska ses som en preliminär bedömning av halterna, utvärderas också. Vidare undersöks, genom känslighetsanalys, hur antaganden om emissionsfaktorer och eldvanor påverkar luftkvaliteten i områdena. En av de åtgärder som utreds är att byta ut gamla vedpannor mot moderna eldstäder. Luftmiljövinsterna av detta undersöks också genomspridningsmodellering.

    Emissionerna från eldstäderna har beräknats utifrån information från sotarregister i de olika kommunerna, där eldstäderna har klassificerats som vedpannor (miljögodkända och ickemiljögodkända), lokaleldstäder, flis- och pelletspannor samt övriga pannor (mest oljepannor). Geolokalisering, dvs. framtagandet av koordinater, har gjorts för de olika eldstäderna i registren baserat på adresser. Med hjälp av modellerade energibehov för ett genomsnittligt meteorologiskt kalenderår för perioden 1960-1990, för ett genomsnittligt småhus, samt antaganden om emissionsfaktorer, eldstäders nyttjandegrad samt verkningsgrad har sedan emissionerna beräknats.

    Lokalskalig spridningsmodellering med en rumslig upplösning om 20 m × 20 m har genomförts för de utvalda tätorterna med den Gaussiska lokalskaliga spridningsmodellen Dispersion, som är samma lokala modell som finns i modellsystemet SIMAIR-ved. Vid spridningsmodelleringen har meteorologiska data från Mesan för kalenderår 2016 och 2017 använts. Bakgrundshalter har inkluderats för PM2.5, men enbart lokalt haltbidrag från småskalig uppvärmning har beräknats för B(a)P; ett schablontillägg av bakgrundshalter för B(a)P har gjorts för varje tätort. Modelleringen har också utvärderats mot preliminära mätresultat (månadsprovtagning) av B(a)P avseende juni- december 2017 i Boliden, Bureå, Backe, Hoting samt Alingsås tätort samt mätningar av PM2.5 i Bureå och Backe (mätningarna har utförts av Svenska Miljöinstitutet IVL på uppdrag av Naturvårdsverket)

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  • 21.
    Andersson, Tage
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    A HEAVY MESOSCALE SNOWFALL EVENT IN NORTHERN GERMANY1991Ingår i: METEOROLOGICAL MAGAZINE, ISSN 0026-1149, Vol. 120, nr 1425, s. 67-68Artikel i tidskrift (Refereegranskat)
  • 22.
    Andersson, Tage
    SMHI, Forskningsavdelningen.
    Aeronautic wind shear and turbulence. A review for forecasts1989Rapport (Övrigt vetenskapligt)
    Abstract [en]

    'Turbulence' in flight operations means all inhomogeneities in the wind field which cause unexpected deviations from the aircraft's intended flight path. It utters itself as bumpiness, which in extreme cases also may cause severe discomfort to passengers and crew, and even be dangerous because persons and loose objects may be tossed around. Even more serious is that in extreme cases the pilot may lose his control of the aircraft, and/or the aircraft may be damaged.

    This is most serious when an aircraft is heavy loaded and flying at a speed just above its stalling speed, as in take-off.

    'Turbulence' is related to the shear of the wind. A sharp wind shear by itself affects the aircraft; due to its inertia the aircraft tries to keep its speed relative to the ground also when the surrounding air has changed it. This affects the lifting forece, causing an acceleration and a change in the aircraft's attitude.

    lf the air flow is laminar, shear does not produce turbulence. However, even if turbulence needs not to be present in strong shear at low altitudes ( NCR, 1983, after Lee and Beckwith, 1981 ) laminary flow belongs to the laboratory, not the atmosphere. In this manual we will mainly talk about wind shear, since this is a meteorological parameter that at least in principle is possible to measure. It has to be understood that wind shear is nearly always accompanied by turbulence (or bumpiness).

    Some forecasting hints will be given in the text. The most important one will, however, be given already here:

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  • 23.
    Andersson, Tage
    SMHI, Forskningsavdelningen.
    Boundary clear air echos in southern Sweden2000Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The C band weather radars of today are sensitive enough to record clear air echos from the boundary layer during the warmer seasons even in latitudes as high as Scandinavia. Such clear air echos have long been recognised in the US and a.o. used to retrieve the wind. Curiously enough, in Europe there has been, and perhaps still is, a wide spread belief among meteorologists that boundary layer clear air echos are absent there. The probable reason is that since European weather radars are almost only used to monitor precipitation, in most countries weak echos, supposed not to represent precipitation, are suppressed. This may be performed in many ways, for instance by using the STC (Sensitivity Time Control, also called Swept Gain) which suppresses echos close to the radar, or by thresholding weak echos in the radar images used. The threshold is usually about 10 dBz, and since most clear air echos are weaker, they do not appear in the images, though the radar rnight have recorded them.

    That these clear air echos actually are echos from the air, as from sharp refractive index gradients, insects or birds, is evident since Doppler radars show that they move, generally approximately with the winds recorded by other means. The exceptions are from targets heading towards a specific goal, as rnigrating birds, birds leaving a nocturnal roost and locust swarms.

    The concept 'clear air echos' refers to echos from a non-precipitating atmosphere. There is no commonly agreed stringent definition of clear air echos.

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  • 24.
    Andersson, Tage
    SMHI, Forskningsavdelningen.
    Isbildning på flygplan1988Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Med isbildning på flygplan avses alla sorters avlagringar av vatten i fast form. Avlagringen kan ske såväl då flygplanet befinner sig på marken som i luften. Den kan finnas på synliga delar som vingar, stabilisatorer och vindrutor, ellerdolt som i förgasare till kolvmotorer. En egenskap har isbildning (nästan undantagslöst) gemensam: Den försämrar planets flygegenskaper. Graden av försämring kan variera från obetydlig till katastrofal. Det faktum att isbildning som avsevärt försämrar planets flygegenskaper är sällsynt gör inte prognostikerns uppgift lättare. Tvärtom, ovanliga fenomen är alltid svåra att förutsäga. Flygning i moln med underkylda vattendroppar resulterar nästan alltid i att ett tunnt isskikt bildas på tex vingframkanterna. I regel blir då försämringen av flygegenskaperna så liten att den inte märks. Sådan isbildning är av föga intresse för flygaren. Däremot är isbildning som ALLVARLIGT försämrar planets flygegenskaper vital. Att förutsäga enbart "isbildning" är därför till liten nytta för piloten. Isbildningens INTENSITET eller SVÅRIGHETSGRAD måste också förutsägas, vilket ytterligare komplicerar meteorologens arbete.Ett tunnt isskikt är dock ej alltid harmlöst. Om rimfrost bildas på vingens översida på ett flygplan på marken blir den släta ytan skrovlig, något som katastrofalt kan försämra lyftkraften.Beroende på flygplanets form avlagras is olika snabbt på olika delar av planet. Isen växer snabbast på spetsiga delar, som antenner, pitotrör och vingframkanter. Isbildningen kan därför också skilja sig från flygplantyp till flygplantyp. Olika flygplantyper reagerar också olika för isbildning. Deltavingade flygplan, som Draken och Viggen, har flygegenskaper som påverkas relativt litet även av ett tjockt islager på den spetsiga vingframkanten.Isbildning uppträder vid stratiforma moln i relativt tunna skikt. Om planet snabbt kan passera genom ett sådant skikt, hinner avlagringen ej bli så mäktig. Men om planet tvingas uppehålla sig länge där, kan avlagringen växa sig mäktig. Exempel på detta är vid landning, då planet har låg sjunkhastighet eller kan tvingas behålla samma höjd en längre tid (holding). Ett annat exempel är VFR-flygning, då planet kan stängas in i ett isbildningsskikt mellan marken och molnbasen.Tunga trafikflygplan har effektiva avisningsanordningar. Därför är de okänsliga för isbildning under flygning. Lätta flygplan och militärflygplan saknar i regel visningsanordningar på vingar och stabilisatorer. Där kan alltså is obehindrat byggas upp, och dessa flygplan är MYCKET KÄNSLIGARE för isbildning. Jetflygplan har i regel avisningsanordningar på luftintagen till motorn/motorerna.Helikoptrar har speciellt stora isbildningsproblem. Särskilt är motorerna (gäller jetmotorer) känsliga. Vid ymnig blötsnö kan snön kväva dem. Is som bildats på luftintagen eller stag på flygkroppen kan lossna (tex om helikoptern når varmare områden och isen börjar smälta) komma in i motorn och skada kompressorn. Is på huvudrotorn försämrar dess lyftkraft och orsakar allvarliga skakningar. Is på stjärtrotorn kan då den lossnar slungas iväg mot andra delar av helikoptern och skada dem. Is på vindrutan är allvarlig, eftersom den förhindrar sikten framåt.Uppenbarligen är isbildning på flygplan ett komplicerat problem. Det är endast delvis meteorologiskt. Identiska meteorologiska förhållanden ger olika grader av isbildning, beroende på flygplantyp och flygoperation. Vidare är pilotens upplevelse av isbildningen subjektiv. Att förutsäga isbildning ingår dock i flygmeteorologens uppgifter.Som nämnts är svår isbildning ett sällsynt fenomen. Andelen haverier som orsakas av isbildning är också relativt liten. Ca 3% av de civila flyghaverierna i USA åren 1973-77 tillskrevs tex isbildning. Dessa haverier blir dock ofta svåra, med dödlig utgång för besättning och passagerare.

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  • 25.
    Andersson, Tage
    SMHI, Forskningsavdelningen.
    Using the Sun to check some weather radar parameters2000Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Precipitation rnonitoring is a rnain task for weather radar applications. In quantitative applications, as estirnation of the rain rate, the fundamental quantity is the rneasurernent of the intensity of the retum signal strength, giving the so called reflectivity factor, or reflectivity, which is the rnain parameter for those estirnates. The calibration of weather radars for this purpose has been a rnain task in radar rneteorology since the first atternpts of estirnating rain rates in the early 1950ies. In spite of this there is still no intemational accepted procedure for this calibration and each rnanufacturer has his own calibration scherne.

    There is evidently a need fora target to calibrate against, which is cornrnon for all radars and easily accessible. This points towards astronornical targets. The rnoon is such a possible target, though the echo from it is too weak for routine calibrations. The sun ernits radiation in the radar frequencies. These signals are already widely used to deterrnine the orientation of the antenna (azirnuth and elevation angle ). The intensity of the radiation in these frequencies is not constant, but is rneasured by sorne observatories and rnay be used as a calibration source.

    The present work is an atternpt to design a calibration or checking procedure that can be used when the radar is working operatively.

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  • 26.
    Andersson, Tage
    SMHI, Forskningsavdelningen.
    VAD winds from C band Ericsson Doppler Weather Radars1998Ingår i: Meteorologische Zeitschrift, ISSN 0941-2948, E-ISSN 1610-1227, Vol. 7, nr 6, s. 309-319Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The VAD (Velocity Azimuth Display) technique for retrieving winds from a single Doppler weather radar is well known as a robust and simple one, though still not used on its merits. Precipitation generally gives VAD winds, but it is less known that even in high latitudes during the warmer seasons the Doppler weather radars of today record enough clear air echos to give wind profiles in the planetary boundary layer. There are, however, few verifications of VAD winds in general, and hardly any concerning clear air. In this paper mainly VAD winds from one Ericsson Doppler Weather Radar in Jonsered, Gothenburg (57.723 degrees N, 12.172 degrees E, 164 m above MSL) are compared to Radiosonde Winds (RAWINDs) from Landwetter (57.668 degrees N, 12.296 degrees E, 155 m above MSL). The sites are about 10 km apart, and the radiosonde is within the range used for the VAD (30 km). The VAD soundings were made each hour, and the radiosoundings every 6th (00, 06, 12 and 18 UTC). About seven months of data were available (9 Dec. 1994 to 14 Feb. 1995 and 28 Jun. to 30 Nov. 1995). The LORAN C system was used to retrieve the RAWINDs during the first period (Dec. 1994 to Feb. 1995), and the OMEGA system was used during the second period. The comparisons are made using the five standard pressure levels, 925, 850, 700, 500 and 400 hPa, corresponding to heights above MSL of about 750, 1450, 3000, 5600 and 7200 m. As overall results, the average differences, in m/s, between the VAD and RAWIND were largest at the lowest (geometrically) levels, and higher up more or less constant with height. This is remarkable, since the wind speed increases with height, and the relative differences thus decrease with height. As an example, the average of the magnitude of the wind vector differences was 3.2 m/s at 925 hPa, but about 2.8 m/s at the higher levels. The differences also tend to be somewhat larger for winds retrieved from clear air echos. In the planetary boundary layer during summer, that is up to about 800 hPa, the availability of VAD winds was about 90 %. The availability decreases with height, and at 400 hPa it was 15 % for the whole period. Comparisons are also performed between VAD winds and winds from a limited area model, HIRLAM.

  • 27.
    Andersson, Tage
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Andersson, M
    SMHI.
    Jacobsson, Caje
    SMHI.
    Nilsson, Stefan
    SMHI.
    THERMODYNAMIC INDEXES FOR FORECASTING THUNDERSTORMS IN SOUTHERN SWEDEN1989Ingår i: METEOROLOGICAL MAGAZINE, ISSN 0026-1149, Vol. 118, nr 1404, s. 141-146Artikel i tidskrift (Refereegranskat)
  • 28.
    Andersson, Tage
    et al.
    SMHI, Forskningsavdelningen.
    Gustafsson, Nils
    SMHI, Forskningsavdelningen, Meteorologi.
    COAST OF DEPARTURE AND COAST OF ARRIVAL - 2 IMPORTANT CONCEPTS FOR THE FORMATION AND STRUCTURE OF CONVECTIVE SNOWBANDS OVER SEAS AND LAKES1994Ingår i: Monthly Weather Review, ISSN 0027-0644, E-ISSN 1520-0493, Vol. 122, nr 6, s. 1036-1049Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A case with intense convective snowbands over the Baltic Sea is examined using the High-Resolution Limited Area Model. The intention is to gain a better insight into the importance of the shape of the cowta, the orography, and the surface roughness on the formation and evolution of the snowbands. Among the factors studied am the shape of the coast from which the air departs and that to which it arrives. These factors are so important that two new concepts-coast of departure and coast of arrival-are introduced.

  • 29.
    Andersson, Tage
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Ivarsson, Karl-Ivar
    SMHI.
    A MODEL FOR PROBABILITY NOWCASTS OF ACCUMULATED PRECIPITATION USING RADAR1991Ingår i: Journal of applied meteorology (1988), ISSN 0894-8763, E-ISSN 1520-0450, Vol. 30, nr 1, s. 135-141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new model for making probability forecasts of accumulated spot precipitation from weather radar data is presented. The model selects a source region upwind of the forecast spot. All pixels (horizontal size 2 x 2 km2) within the source region are considered, having the same probability of hitting the forecast spot. A pixel hitting the forecast spot is supposed to precipitate there a short time (about 10 min.). A drawing is performed, and a frequency distribution of accumulated precipitation during the first time step of the forecast is obtained. A second drawing gives the frequency distribution of accumulated precipitation during the first to second time step, a third one during the first to third, and so on until the end of the forecast period is reached. A number of forecasts for 1-h accumulated precipitation, with lead times of 0, 1, and 2 h, have been performed and verified. The forecasts for 0-h lead time got the highest Brier skill scores, +50% to 60% relative to climatological forecasts for accumulated precipitation below 1 mm.

  • 30.
    Andersson, Tage
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Lindgren, Bo
    SMHI.
    A SEA-BREEZE FRONT SEEN BY RADAR1992Ingår i: METEOROLOGICAL MAGAZINE, ISSN 0026-1149, Vol. 121, nr 1443, s. 239-241Artikel i tidskrift (Refereegranskat)
  • 31.
    Andersson, Tage
    et al.
    SMHI, Forskningsavdelningen.
    Mattisson, Ingemar
    SMHI.
    A field test of thermometer screens1991Rapport (Övrigt vetenskapligt)
    Abstract [en]

    For a period of nearly one year temperature readings from small sensors (high quality platinum resistance thermometers) in conventional screens (Stevensson type) and emaller screens (Lambrecht, Young and Vaisala) have been compared to those from a sensor of the same type in a ventilated screen (Teledyne). The test was financially supported by the Swedish Civil Board of Aviation and CDS Mätteknik, Skara. The reading from the Teledyne screen was used as reference and considered the 'true' air temperature. The deviations from the reference were mainly due to two factors:- the thermal inertia of the screens- radiation errors.The thermal inertia is largest for the larger screens. With rapid air temperature changes and calm winds the larger (Stevenson) screens lag behind much more than the smaller ones. Also the radiation errors are largest for calm winds. The extreme errors then occur during calm winds and clear sky. The errors found are larger than given in the literature. The largest error noted, +3. 6°C for one of the Stevenson screens, occurred a calm, clear evening. Generally the extreme errors occurred at sunset and sunrise, not in the a~ternoon when the irradiation has its maximum, because it then usually is windy. Generally the smaller screens followed the reference better than the Stevenson ones. However, with calm winds, clear sky and snow cover the small screens may rapidly get overheated. The averages for longer periods (months)

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  • 32.
    Andersson, Tage
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Nilsson, Stefan
    SMHI, Samhälle och säkerhet.
    TOPOGRAPHICALLY INDUCED CONVECTIVE SNOWBANDS OVER THE BALTIC SEA AND THEIR PRECIPITATION DISTRIBUTION1990Ingår i: Weather and forecasting, ISSN 0882-8156, E-ISSN 1520-0434, Vol. 5, nr 2, s. 299-312Artikel i tidskrift (Refereegranskat)
  • 33.
    Andersson, Tage
    et al.
    SMHI, Forskningsavdelningen.
    Persson, Ola
    SMHI.
    Lindström, Bengt
    SMHI.
    Radarmeteorologi1985Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Radarmeteorologi

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  • 34. Ansell, T. J.
    et al.
    Jones, P. D.
    Allan, R. J.
    Lister, D.
    Parker, D. E.
    Brunet, M.
    Moberg, A.
    Jacobeit, J.
    Brohan, P.
    Rayner, N. A.
    Aguilar, E.
    Alexandersson, Hans
    SMHI.
    Barriendos, M.
    Brandsma, T.
    Cox, N. J.
    Della-Marta, P. M.
    Drebs, A.
    Founda, D.
    Gerstengarbe, F.
    Hickey, K.
    Jonsson, T.
    Luterbacher, J.
    Nordli, O.
    Oesterle, H.
    Petrakis, M.
    Philipp, A.
    Rodwell, M. J.
    Saladie, O.
    Sigro, J.
    Slonosky, V.
    Srnec, L.
    Swail, V.
    Garcia-Suarez, A. M.
    Tuomenvirta, H.
    Wang, X.
    Wanner, H.
    Werner, P.
    Wheeler, D.
    Xoplaki, E.
    Daily mean sea level pressure reconstructions for the European-North Atlantic region for the period 1850-20032006Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 19, nr 12, s. 2717-2742Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of a daily historical European-North Atlantic mean sea level pressure dataset (EMSLP) for 1850-2003 on a 5 latitude by longitude grid is described. This product was produced using 86 continental and island stations distributed over the region 25 degrees-70 degrees N, 70 degrees W-50 degrees E blended with marine data from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS). The EMSLP fields for 1850-80 are based purely on the land station data and ship observations. From 1881, the blended land and marine fields are combined with already available daily Northern Hemisphere fields. Complete coverage is obtained by employing reduced space optimal interpolation. Squared correlations (r(2)) indicate that EMSLP generally captures 80%-90% of daily variability represented in an existing historical mean sea level pressure product and over 90% in modern 40-yr European Centre for Medium-Range Weather Forecasts Re-Analyses (ERA-40) over most of the region. A lack of sufficient observations over Greenland and the Middle East, however, has resulted in poorer reconstructions there. Error estimates, produced as part of the reconstruction technique, flag these as regions of low confidence. It is shown that the EMSLP daily fields and associated error estimates provide a unique opportunity to examine the circulation patterns associated with extreme events across the European-North Atlantic region, such as the 2003 heat wave, in the context of historical events.

  • 35.
    Appelqvist, Peter
    et al.
    SMHI.
    Karlsson, Anders
    Miljölnvest AB..
    Nationell emissionsdatabas för utsläpp till luft - Förstudie1999Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    På uppdrag av Naturvårdsverket, Miljödataenheten, har SMHI under 1999 genomfört ett forskningsuppdrag i form av en förstudie avseende en Nationell Emissionsdatabas (EDB) för utsläpp till luft. Projektet syftar till att utreda och beskriva alternativa lösningar för hur en sådan EDB skulle kunna utformas för att Naturvårdsverket skall kunna uppfylla kraven på internationell rapportering av emissioner från Sverige. Projektet syftar också till att klargöra hur utsläppsinformation skall kunna inhämtas och aggregeras från låg nivå, så att informationen även kan nyttjas på regional och lokal nivå. Vidare har den pågående utvecklingen mot att fördela ansvaret för miljöfrågor till statliga verk eller myndigheter utanför Naturvårdsverket varit en uttalad förutsättning för arbetet med förstudien.

    Ladda ner fulltext (pdf)
    fulltext
  • 36. 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, 1877-20122018Ingår i: Earth System Science Data, ISSN 1866-3508, E-ISSN 1866-3516, Vol. 10, nr 3, s. 1613-1635Artikel i tidskrift (Refereegranskat)
    Ladda ner fulltext (pdf)
    fulltext
  • 37.
    Asker, Christian
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Andersson, Camilla
    SMHI, Forskningsavdelningen, Luftmiljö.
    Segersson, David
    SMHI, Forskningsavdelningen, Luftmiljö.
    CLAIR-O3 - befolkningsexponering marknära ozon i Göteborg och Stockholm2021Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Vi har tagit fram en flexibel nedskalningsmetodik för marknära ozon, CLAIR-O3-metoden.Denna metodik nyttjar högupplösta utsläpp av kväveoxider för att skala ner modellberäknatozon på grövre upplösning. Detta har en vinst i form av ökad upplösning i närhet till utsläppav kväveoxider, t.ex. i urban miljö och närhet till stora vägar/industrier/bostadsområden.Metoden tillåter, utöver den ökade upplösningen, även en förbättring (korrigering) avregionalskaliga halter med regionalskaliga mätningar, såsom i MATCH sverigesystemet, mendet är inte nödvändigt utan nedskalningen av marknära ozon kan appliceras direkt påmodellerad bakgrundshalt. I denna studie har vi utgått från nationella bakgrundshalterframtaget med MATCH (5x5km2 upplösning), och korrigerat mot regionalabakgrundsmätningar på timskala.Vi har beräknat timhalter av marknära ozon för två svenska städer, Stockholm och Göteborg,för 2015 på 100x100m2 upplösning och använt dessa för att skatta befolkningsexponering istädernas kommuner. Högst exponering är generellt i Göteborg under 2015, med allra högstexponering i Kungälvs kommun. Högst exponering i Stockholm är i de ostliga kommunernaÖsteråker, Värmdö och Vaxholm medan den lägsta exponeringen är i Sundbyberg, Solna ochStockholms kommun.Våra modellresultat jämför sig väl mot i metoden oberoende mätdata, och mot enregressionsmetod som baseras på regression av mätningar. Denna metodik är tillämpbar överett större område, som hela Sverige, och längre tidsperioder, då den inte är beroende avtillgång till mätdata.Det finns fortsatta möjliga ytterligare metod och modellförbättringar. En förbättringsmöjlighetär förfinad hantering av hur regionalskalig halt först in i nedskalningsmodellen, vilket skullejämna ut det grövre rutmönstret i kartorna. En annan är att införa nedskalning medatmosfärisk stabilitet och höjd i landskapet vilket skulle möjliggöra beskrivning av högupplöstväxtexponering, vilket enbart hanteras i närhet till direkta utsläpp i denna metod.Metoden skulle kunna införas i miljöövervakningen med MATCH Sverigesystemet.

    Ladda ner fulltext (pdf)
    CLAIR-O3 - befolkningsexponering marknära ozon i Göteborg och Stockholm
  • 38. Askjaer, Thomas Gravgaard
    et al.
    Zhang, Qiong
    Schenk, Frederik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ljungqvist, Fredrik Charpentier
    Lu, Zhengyao
    Brierley, Chris M.
    Hopcroft, Peter O.
    Jungclaus, Johann
    Shi, Xiaoxu
    Lohmann, Gerrit
    Sun, Weiyi
    Liu, Jian
    Braconnot, Pascale
    Otto-Bliesner, Bette L.
    Wu, Zhipeng
    Yin, Qiuzhen
    Kang, Yibo
    Yang, Haijun
    Multi-centennial Holocene climate variability in proxy records and transient model simulations2022Ingår i: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 296, artikel-id 107801Artikel i tidskrift (Refereegranskat)
    Ladda ner fulltext (pdf)
    Multi-centennial Holocene climate variability in proxy records and transient model simulations
  • 39. Astrom, Daniel Oudin
    et al.
    Adolfsson, Rolf
    Segersson, David
    SMHI, Forskningsavdelningen, Luftmiljö.
    Forsberg, Bertil
    Oudin, Anna
    Local Contrasts in Concentration of Ambient Particulate Air Pollution (PM2.5) and Incidence of Alzheimer's Disease and Dementia: Results from the Betula Cohort in Northern Sweden Comment2021Ingår i: Journal of Alzheimer's Disease, ISSN 1387-2877, E-ISSN 1875-8908, Vol. 81, nr 1, s. 83-85Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Exposure to fine particulate air pollution (PM2.5) is emerging as a risk factor for Alzheimer's disease (AD), but existing studies are still limited and heterogeneous. We have previously studied the association between dementia (AD and vascular dementia) and PM2.5 stemming from vehicle exhaust and wood-smoke in the Betula cohort in Northern Sweden. The aim of this commentary is to estimate the association between total PM2.5 and dementia in the Betula cohort, which is more relevant to include in future meta-estimates than the source-specific estimates. The hazard ratio for incident dementia associated with a 1 mu g/m(3) increase in local PM2.5 was 1.38 (95% confidence interval: 0.99 - 1.92). The interpretation of our results is that they indicate an association between local contrasts in concentration of PM2.5 at the residential address and incidence of dementia in a low-level setting.

    Ladda ner fulltext (pdf)
    Local Contrasts in Concentration of Ambient Particulate Air Pollution (PM2.5) and Incidence of Alzheimer’s Disease and Dementia: Results from the Betula Cohort in Northern Sweden
  • 40. 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 spectroradiometers2001Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 106, nr D12, s. 12509-12525Artikel i tidskrift (Refereegranskat)
    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.

  • 41. 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 2009-20102013Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 13, nr 12, s. 6049-6064Artikel i tidskrift (Refereegranskat)
    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.

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    fulltext
  • 42. Barre, Jerome
    et al.
    Petetin, Herve
    Colette, Augustin
    Guevara, Marc
    Peuch, Vincent-Henri
    Rouil, Laurence
    Engelen, Richard
    Inness, Antje
    Flemming, Johannes
    Garcia-Pando, Carlos Perez
    Bowdalo, Dene
    Meleux, Frederik
    Geels, Camilla
    Christensen, Jesper H.
    Gauss, Michael
    Benedictow, Anna
    Tsyro, Svetlana
    Friese, Elmar
    Struzewska, Joanna
    Kaminski, Jacek W.
    Douros, John
    Timmermans, Renske
    Robertson, Lennart
    SMHI, Forskningsavdelningen, Luftmiljö.
    Adani, Mario
    Jorba, Oriol
    Joly, Mathieu
    Kouznetsov, Rostislav
    Estimating lockdown-induced European NO2 changes using satellite and surface observations and air quality models2021Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 21, nr 9, s. 7373-7394Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study provides a comprehensive assessment of NO2 changes across the main European urban areas induced by COVID-19 lockdowns using satellite retrievals from the Tropospheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5p satellite, surface site measurements, and simulations from the Copernicus Atmosphere Monitoring Service (CAMS) regional ensemble of air quality models. Some recent TROPOMI-based estimates of changes in atmospheric NO2 concentrations have neglected the influence of weather variability between the reference and lockdown periods. Here we provide weather-normalized estimates based on a machine learning method (gradient boosting) along with an assessment of the biases that can be expected from methods that omit the influence of weather. We also compare the weather-normalized satellite-estimated NO2 column changes with weather-normalized surface NO2 concentration changes and the CAMS regional ensemble, composed of 11 models, using recently published estimates of emission reductions induced by the lockdown. All estimates show similar NO2 reductions. Locations where the lockdown measures were stricter show stronger reductions, and, conversely, locations where softer measures were implemented show milder reductions in NO2 pollution levels. Average reduction estimates based on either satellite observations (-23 %), surface stations (-43 %), or models (-32 %) are presented, showing the importance of vertical sampling but also the horizontal representativeness. Surface station estimates are significantly changed when sampled to the TROPOMI overpasses (-37 %), pointing out the importance of the variability in time of such estimates. Observation-based machine learning estimates show a stronger temporal variability than model-based estimates.

    Ladda ner fulltext (pdf)
    Estimating lockdown-induced European NO2 changes using satellite and surface observations and air quality models
  • 43. Barthelmie, R
    et al.
    Larsen, G
    Pryor, S
    Jorgensen, H
    Bergstrom, H
    Schlez, W
    Rados, K
    Lange, B
    Volund, P
    Neckelmann, S
    Mogensen, S
    Schepers, G
    Hegberg, T
    Folkerts, L
    Magnusson, Mikael
    SMHI, Samhälle och säkerhet.
    ENDOW (Efficient development of offshore wind farms): Modelling wake and boundary layer interactions2004Ingår i: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824, Vol. 7, nr 3, s. 225-245Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    While experience gained through the offshore wind energy projects currently operating is valuable, a major uncertainty in estimating power production lies in the prediction of the dynamic links between the atmosphere and wind turbines in offshore regimes. The objective of the ENDOW project was to evaluate, enhance and interface wake and boundary layer models for utilization offshore. The project resulted in a significant advance in the state of the art in both wake and marine boundary layer models, leading to improved prediction of wind speed and turbulence profiles within large offshore wind farms. Use of new databases from existing offshore wind farms and detailed wake profiles collected using sodar provided a unique opportunity to undertake the first comprehensive evaluation of wake models in the offshore environment. The results of wake model performance in different wind speed, stability and roughness conditions relative to observations provided criteria for their improvement. Mesoscale model simulations were used to evaluate the impact of thermal flows, roughness and topography on offshore wind speeds. The model hierarchy developed under ENDOW forms the basis of design tools for use by wind energy developers and turbine manufacturers to optimize power output from offshore wind farms through minimized wake effects and optimal grid connections. The design tools are being built onto existing regional-scale models and wind farm design software which was developed with EU funding and is in use currently by wind energy developers. Copyright (C) 2004 John Wiley Sons, Ltd.

  • 44. Bech, J.
    et al.
    Gjertsen, U.
    Haase, Gunther
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Modelling weather radar beam propagation and topographical blockage at northern high latitudes2007Ingår i: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 133, nr 626, s. 1191-1204Artikel i tidskrift (Refereegranskat)
    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.

  • 45. Becker, Daniel
    et al.
    Heitland, Jonas
    Carlsson, Philip T. M.
    Elm, Jonas
    Olenius, Tinja
    SMHI, Forskningsavdelningen, Meteorologi.
    Toedter, Sophia
    Kharrazizadeh, Amir
    Zeuch, Thomas
    Real-time monitoring of aerosol particle formation from sulfuric acid vapor at elevated concentrations and temperatures2022Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084Artikel i tidskrift (Refereegranskat)
    Ladda ner fulltext (pdf)
    Real-time monitoring of aerosol particle formation from sulfuric acid vapor at elevated concentrations and temperatures
  • 46. Belova, Evgenia
    et al.
    Kirkwood, Sheila
    Voelger, Peter
    Chatterjee, Sourav
    Satheesan, Karathazhiyath
    Hagelin, Susanna
    SMHI, Forskningsavdelningen, Meteorologi.
    Lindskog, Magnus
    SMHI, Forskningsavdelningen, Meteorologi.
    Körnich, Heiner
    SMHI, Forskningsavdelningen, Meteorologi.
    Validation of Aeolus winds using ground-based radars in Antarctica and in northern Sweden2021Ingår i: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 14, nr 8, s. 5415-5428Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Winds measured by lidar from the Aeolus satellite are compared with winds measured by two ground-based radars - MARA in Antarctica (70.77 degrees S, 11.73 degrees E) and ES-RAD (67.88 degrees N, 21.10 degrees E) in Arctic Sweden - for the period 1 July-31 December 2019. Aeolus is a demonstrator mission to test whether winds measured by Doppler lidar from space can have sufficient accuracy to contribute to improved weather forecasting. A comprehensive programme of calibration and validation has been undertaken following the satellite launch in 2018, but, so far, direct comparison with independent measurements from the Arctic or Antarctic regions have not been made. The comparison covers heights from the low troposphere to just above the tropopause. Results for each radar site are presented separately for Rayleigh (clear) winds, Mie (cloudy) winds, sunlit ("summer") and non-sunlit ("winter") seasons, and ascending and descending satellite tracks. Horizontally projected line-of-sight (HLOS) winds from Aeolus, reprocessed using baseline 2B10, for passes within 100 km of the radar sites, are compared with HLOS winds calculated from 1 h averaged radar horizontal wind components. The agreement in most data subsets is very good, with no evidence of significant biases (<1ms(-1)). Possible biases are identified for two subsets (about -2ms(-1) for the Rayleigh winds for the descending passes at MARA and about 2ms(-1) for the Mie winds for the ascending passes at ESRAD, both in winter), but these are only marginally significant. A robust significant bias of about 7ms(-1) is found for the Mie winds for the ascending tracks at MARA in summer. There is also some evidence for increased random error (by about 1ms(-1) / for the Aeolus Mie winds at MARA in summer compared to winter. This might be related to the presence of sunlight scatter over the whole of Antarctica as Aeolus transits across it during summer.

    Ladda ner fulltext (pdf)
    Validation of Aeolus winds using ground-based radars in Antarctica and in northern Sweden
  • 47. Belova, Evgenia
    et al.
    Voelger, Peter
    Kirkwood, Sheila
    Hagelin, Susanna
    SMHI, Forskningsavdelningen, Meteorologi.
    Lindskog, Magnus
    SMHI, Forskningsavdelningen, Meteorologi.
    Körnich, Heiner
    SMHI, Forskningsavdelningen, Meteorologi.
    Chatterjee, Sourav
    Satheesan, Karathazhiyath
    Validation of wind measurements of two mesosphere-stratosphere-troposphere radars in northern Sweden and in Antarctica2021Ingår i: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 14, nr 4, s. 2813-2825Artikel i tidskrift (Refereegranskat)
    Ladda ner fulltext (pdf)
    Validation of wind measurements of two mesosphere-stratosphere-troposphere radars in northern Sweden and in Antarctica
  • 48. Benas, Nikos
    et al.
    Meirink, Jan Fokke
    Karlsson, Karl-Göran
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Stengel, Martin
    Stammes, Piet
    Satellite observations of aerosols and clouds over southern China from 2006 to 2015: analysis of changes and possible interaction mechanisms2020Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 20, nr 1, s. 457-474Artikel i tidskrift (Refereegranskat)
    Ladda ner fulltext (pdf)
    fulltext
  • 49. Benas, Nikos
    et al.
    Solodovnik, Irina
    Stengel, Martin
    Hueser, Imke
    Karlsson, Karl-Göran
    SMHI, Forskningsavdelningen, Meteorologi.
    Håkansson, Nina
    SMHI, Forskningsavdelningen, Meteorologi.
    Johansson, Erik
    SMHI, Forskningsavdelningen, Meteorologi.
    Eliasson, Salomon
    SMHI, Forskningsavdelningen, Meteorologi.
    Schroeder, Marc
    Hollmann, Rainer
    Meirink, Jan Fokke
    CLAAS-3: the third edition of the CM SAF cloud data record based on SEVIRI observations2023Ingår i: Earth System Science Data, ISSN 1866-3508, E-ISSN 1866-3516, Vol. 15, nr 11, s. 5153-5170Artikel i tidskrift (Refereegranskat)
    Ladda ner fulltext (pdf)
    CLAAS-3: the third edition of the CM SAF cloud data record based on SEVIRI observations
  • 50.
    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 (Övrigt vetenskapligt)
    Abstract [sv]

    Sverige var ett föregångsland inom numeriska vädderprognoser och den allra första operativa väderprognosen gjordes redan 1954 på det Internationella Meteorologiska Institutet i Stockholm. SMHI kom igång senare, men 1961 startade man ett långsiktigt program för NWP (numerical weather prediction). Projektet växte gradvis under 1960-talet och blev så småningom en central komponent i SMHIs prognostjänst. En utmaning under de tidiga åren var de begränsade dataresurserna med primitiv programvara, och med dagens mått begränsat minnesutrymme och låg beräkningshastighet. För att kompensera dessa brister krävdes både beslutsamhet och ett stort mått av kreativitet. Som en central komponent i arbetet utvecklade NWP-gruppen datorsystemet MAC (Meteorological Auto Code) som här beskrivs i detalj samt också alla de beräkningsprogram som krävdes för prognostjänsten. Detta inkluderade olika prognosmodeller, analys samt program för databehandling och observationskontroll samt produktion av prognosresultaten i grafisk eller digital form.

    Det är vår förhoppning att f´öreliggande artikel skall ge den yngre generationen en inblick i hur det var att syssla med NWP under 1960-talet.

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    fulltext
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