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  • 2151.
    Wern, Lennart
    SMHI, Core Services.
    Extrema byvindar i Orrefors1986Report (Other academic)
  • 2152.
    Wern, Lennart
    SMHI, Core Services.
    Luftfuktighet: Variationer i Sverige2014Report (Other academic)
    Abstract [en]

    This report gives a general description of water vapour which is a transparent and odourless gas, how this gas varies geographically outdoors in Sweden as well as the diurnal and annual variation. Humidity data from 121 automatic weather stations that were operational during the period 1996-2012 was used. The measurements were taken at 1.5 to 2 meters above the ground level. Different measuring instruments for humidity are presented and also different humidity measurements like dew point, wet bulb, absolute humidity, mixing ratio, enthalpy etc. The absolute humidity which is the mass of water vapour in a cubic meter of air is highest in summer and lowest during the coldest days in winter. The highest values are measured along the coasts of southern Sweden and the value decreases northwards and with distance from the coast. Diurnal variation of the absolute humidity is in average relatively small. In addition, monthly mean water vapour is studied for various months since 1951. Digitized humidity data have not been available before in 1951. Ten stations are used, from Bredåkra in the south of Sweden to Arjeplog in the north, for calculating monthly averages. The months May, August and November have been chosen together with the annual value. The absolute humidity increased during the three months and also the annual value. For the annual value and for May and August the increase is statistically significant not for November. There is no statistically significant change of the average relative humidity during the period 1951-2012 for the average of ten selected stations for the months of May, August or November. If the temperature drops to the dew point the air becomes saturated with water vapour and the relative humidity becomes 100 %. If the temperature drops further the water vapour condensates to water droplets and fog, dew or frost is formed. The highest dew point reported in Sweden is 23.8 °C at Fårö north of the island Gotland on 29 July 1994 and in Hällum in Västergötland on 30 June 1997. At the latter occasion the temperature was 28.4 °C and the relative humidity 76%. The relative humidity is usually given in percentage (%) that is a measure of how much water vapour the air contains compared to how much water vapour that the air can contain as a maximum at the ambient temperature. The amount of water vapour that can occur as gas form increases with temperature. Low relative humidity is common during spring and early summer, while high relative humidity occurs during nights and during winter. In May, when the sea water is cool, the relative humidity is higher along the Swedish coast compared to inland. In November, when the sea water is warmer than the land, there is a reverse relationship; the relative humidity is lower on the coast compared to inland. In Helsingborg, the relative humidity is in average 50-60% when the temperature is +25 °C, but when the temperature is between 0 and +10 °C the humidity is much higher, 90 to 100 %.

  • 2153.
    Wern, Lennart
    SMHI, Core Services.
    Snödjup i Sverige 1904/05 – 2013/142015Report (Other academic)
    Abstract [sv]

    Rapporten ger en beskrivning av snöförhållandena i Sverige under vintrarna 1904/05 till 2013/14. Speciellt har vinterns största snödjup, antal dagar med snötäcke och stora snödjupsökningar under ett dygn studerats. Snödjupsrekord för olika månader och landsdelar har sammanställts. Svåra snövintrar beskrivs liksom olika exempel på extrema snöfall och snödjup med återkomsttiden 10 och 50 år. Vid en jämförelse av vintrarna under perioderna 1991 – 2014 med 1961 – 1990 så har vinterns största snödjup och antal dagar med snötäcke minskat i nästan hela landet. Stora snödjupsökningar från en dag till nästa beror ofta på så kallade snökanoner som oftast bildas över Östersjön vid vind från öster. Speciellt utsatt för snökanoner är Norrlandskusten från Skellefteå ner till Gävle men även Smålandskusten, Vänern och Vättern är drabbat. Den vinter som varit snörikast är 1965/66 om man ser till vinterns största snödjup i Sverige som helhet. I olika delar av Sverige har det under andra vintrar förekommit större snödjup än under 1965/66. Exempelvis var det extremt mycket snö i fjällen 1988/89 och vintern 2009/10 var den snörikaste vintern i Götaland under hela den studerade perioden.

  • 2154.
    Wern, Lennart
    SMHI, Core Services.
    Spridningsberäkningar för ASEA transformers i Ludvika1985Report (Other academic)
  • 2155.
    Wern, Lennart
    SMHI, Core Services.
    Spridningsberäkningar för ett kraftvärmeverk i Sundbyberg1986Report (Other academic)
  • 2156.
    Wern, Lennart
    SMHI, Core Services.
    Spridningsberäkningar för lösningsmedel i Tibro1986Report (Other academic)
  • 2157.
    Wern, Lennart
    SMHI, Core Services.
    Spridningsberäkningar för svavelsyrafabrik i Falun1986Report (Other academic)
  • 2158.
    Wern, Lennart
    SMHI, Core Services.
    Spridningsberäkningar för Volvo BM ABs anläggning i Braås1986Report (Other academic)
  • 2159.
    Wern, Lennart
    SMHI, Core Services.
    Spridningsberäkningar för Volvo Hallsbergverken1986Report (Other academic)
  • 2160.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Sveriges vindklimat 1901-2008: Analys av trend i geostrofisk vind2009Report (Other academic)
    Abstract [sv]

    En studie har gjorts hur vinden har varierat i Sverige under perioden 1901 - 2008. Eftersom det saknas långa homogena mätserier av vindhastighet i Sverige har vi utgått från tryckmätningar och beräknatden s.k. geostrofiska vinden i elva trianglar som täcker Sverige. Eftersom bara tre observationer per dag (morgon, middag och kväll) har funnits att tillgå så kan det ha blåst mer mellan observationerna.Ett stort arbete har lagts ner på att kontrollera och rätta felaktiga observationer. Mellan åren 1951 och 2008 har varje observerat värde jämförts med ett interpolerat värde. Om skillnaden varit mer än 4 - 5 hPa har en karta analyserats för att kunna avgöra om det i databasen lagrade värdet varit korrekt. Kanske tusen tryckkartor har analyserats. Även två närliggande stationers observationer har jämförts till exempel Bromma och Observatoriekullen. Före 1951 har granskningsarbetet varit begränsat eftersom digitaliserade data saknas för fler stationer än de som ingår i denna undersökning.Förändringen av vindklimatet i elva trianglar som täcker huvuddelen av Sverige har studerats medhjälp av flera olika mått, bland annat:- Årets högsta vindhastighet- Årets medelvindhastighet- Antal fall på minst 25 m/s under året- Potentiell vindenergi under åretÅrets högsta geostrofiska vindhastighet har även jämförts med högsta havsvattenstånd och skogsskador.I det studerade materialet inträffade den absolut högsta geostrofiska vindhastigheten den 13 januari 1984 i den sydligaste triangeln Göteborg - Visby - Lund. Då beräknades den geostrofiska vindhastigheten till 66 m/s och vindriktningen var 235°.Denna undersökning visar bland annat att:- Årets högsta vindhastighet har ökat i fem trianglar och minskat i sex trianglar sedan 1951. Den sammanvägde trenden i Sverige visar på en svag ökning som inte är statistiskt signifikant.- Antal tillfällen per år då vindhastigheten varit minst 25 m/s har minskat i sju av de elva trianglarna sedan 1951.- Medelvindhastigheten har minskat i tio av de elva trianglarna sedan 1951. För fyra trianglar i norra Sverige är denna minskning statistiskt signifikant. Sammantaget för Sverige har medelvindhastigheten minskat med 4 %.- På samma sätt har den potentiella vindenergin minskat i dessa tio trianglar sedan 1951-talet. Minskningen är statistiskt signifikant i de fyra nordliga trianglarna. Sammantaget för Sverige har energin minskat med 7 %.

  • 2161.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Fredriksson, Ulf
    SMHI, Core Services.
    Spridningsberäkning för Kockums Plåt-teknik, Ronneby1986Report (Other academic)
  • 2162.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Fredriksson, Ulf
    SMHI, Core Services.
    Ring, Sture
    SMHI, Professional Services.
    Spridningsberäkningar för lösningsmedel i Tidaholm1986Report (Other academic)
  • 2163.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    German, Jonas
    SMHI.
    Korttidsnederbörd i Sverige 1995 - 20082009Report (Other academic)
    Abstract [sv]

    Korta men intensiva regnhändelser är mycket viktiga inom bland annat urban hydrologi då vi här har att göra med snabba förlopp där avrinningen sker från små ytor som till stor del är hårdgjorda. Nederbördsserier med hög upplösning har därför mycket stor betydelse för all planering, analys och dimensionering av dagvattensystem, oavsett om det är frågan om rörnät eller öppna diken. Regn med varaktighet 15 min till 96 timmar har studerats genom att analysera nederbördsdata från SMHIs nät av automatiska väderstationer.Dessa stationer började installeras under våren 1995 och från början av 1996 var de flesta stationer igång. Den period vi har studerat är maj 1995 till september 2008. 114 automatstationerna har registrerat nederbörd under någon del av denna period. Sammanlagt finns 1211 stationsår med 15 minuters nederbörd. Data har granskats och ett mindre antal orimliga observationer har tagits bort eller rättats. Sammanställningar av årets största regn med olika varaktigheter har gjorts. Nederbördsmängder med olika varaktighet från 15 min till 96 timmar för olika återkomsttider har beräknats med extremvärdesanalys.Den studerade perioden är för kort och antalet stationer är för få för att bestämma regionala skillnader i Sverige av korttidsnederbörd. Därför har medelvärden av korttidsnederbörd för hela Sverige beräknats. Resultat har jämförts med tidigare studier av Dahlström (2006) och Hernebring (2006). Överensstämmelsen är god för kortare regn och kortare återkomsttider.

  • 2164.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Kindell, Sven
    SMHI, Professional Services.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Luktberäkningar för AB ELMO i Flen1986Report (Other academic)
  • 2165.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Spridningsberäkningar för Volvos planerade bilfabrik i Uddevalla - energicentralen1985Report (Other academic)
  • 2166.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Ring, Sture
    SMHI, Professional Services.
    Spridningsberäkningar för ny ugn, SSAB II1986Report (Other academic)
  • 2167.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Ring, Sture
    SMHI, Professional Services.
    Spridningsberäkningar för Västhamns-verket HKV1 i Helsingborg1986Report (Other academic)
  • 2168.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Ring, Sture
    SMHI, Professional Services.
    Spridningsberäkningar, SSAB1986Report (Other academic)
  • 2169.
    Wesslander, Karin
    SMHI, Core Services.
    Coastal eutrophication status assessment using HEAT 1.0 (WFD methodology) versus HEAT 3.0 (MSFD methodology) and  Development of an oxygen consumption  indicator2017Report (Other academic)
    Abstract [en]

    This report contains two parts which are self standing reports and a contribution to the HELCOM project EUTRO-OPER. The work has been funded and commissioned by SwAM (Swedish agency for marine and water management) 2014-2015.

    • Coastal eutrophication status assessment using HEAT 1.0 (WFD methodology) versus HEAT 3.0 (MSFD methodology)

    Eutrophication status is assessed nationally in coastal waters within the Water Framework Directive (WFD) and in open sea areas within the Marine Strategy Framework Directive (MSFD). Both WFD and MSFD consider eutrophication but with different approaches and it is therefore a need for harmonisation in the assessment process.   The Excel based tool HEAT (HELCOM Eutrophication Assessment Tool) has been used in previous assessments in the HELCOM region. There are two versions of the tool; HEAT 1.0 and HEAT 3.0, the first is based on the WFD methodology and the second is based on the MSFD methodology. The main difference between HEAT 1.0 and HEAT 3.0 is how the indicators are grouped. Here we assess the eutrophication status in coastal waters by applying HEAT and compare the results with the national WFD assessments. The present test includes data on 33 selected coastal water bodies in five countries: Estonia, Finland, Latvia, Poland and Sweden. Data on reference condition, acceptable deviation, status and class boundaries of all indicators used in WFD for reporting ecological status (biological and physical-chemical) have been provided for each tested water body. The data has been inserted in the HEAT 1.0 and HEAT 3.0 tools and been compared with the national WFD assessments.   Both HEAT versions gave lower status in more than 50 % of the cases. For some tests the status changed to sub-GES from GES when HEAT is applied. The good/moderate boundary is the same in both HEAT and the WFD while the lower class boundaries in general are stricter in HEAT, which explains the lower status. In national WFD assessments expert judgment is used when there is little, no or very uncertain in situ data. The status in HEAT is given by the one-out-all-out principle but it is still possible to include expert judgment through the weighting factors.

    • Development of an oxygen consumption indicator

    It was investigated if the oxygen consumption can be used as an oxygen indicator for the Baltic Sea. The method is based on the idea of calculating the oxygen consumption in a stabile layer below the productive zone during summer and relating this to nutrient concentrations. With more nutrients available there is an increased biological production. By estimating how much oxygen is needed to mineralise the biological material it may be possible to link the oxygen consumption to eutrophication.

    The oxygen consumption was calculated for the BY15-Gotland Deep in the Eastern Gotland Basin. We identified a stabile layer between 30 and 50 m and a large change in both oxygen and nutrients from June to August. However, the oxygen consumption had a very high inter-annual variation and there were no significant correlation with the winter mean of nutrient concentrations. It was not possible to calculate the diffusion between the layers because of too sparse measurements at the stratification which limits the method. The calculation of the diffusion is however possible to improve with a model. Further on, the depth of the stabile layer is varying between areas and also between years.   We realised that the method has too many restrictions to be a functional indicator. A functional indicator shall not be dependent on heavy modelling or demand too much on expert judgement. We also investigated if a possible candidate to use as a more simple oxygen consumption indicator could be the use of oxygen saturation at a specific depth. If we assume that the temperature has not changed much since the establishment of stratification we may expect that changes in oxygen saturation observed in August at this depth would be caused by the biological oxygen consumption occurring during late spring and summer. The correlation with winter mean nutrients slightly improved in this case.

  • 2170.
    Wesslander, Karin
    SMHI, Core Services.
    Coastal eutrophication status assessment using HEAT 1.0 (WFD methodology) versus HEAT 3.0 (MSFD methodology) and Development of an oxygen consumption indicator2017Report (Other academic)
    Abstract [en]

    This report contains two parts which are self standing reports and a contribution to the HELCOM project EUTRO-OPER. The work has been funded and commissioned by SwAM (Swedish agency for marine and water management) 2014-2015.

    • Coastal eutrophication status assessment using HEAT 1.0 (WFD methodology) versus HEAT 3.0 (MSFD methodology)

    Eutrophication status is assessed nationally in coastal waters within the Water Framework Directive (WFD) and in open sea areas within the Marine Strategy Framework Directive (MSFD). Both WFD and MSFD consider eutrophication but with different approaches and it is therefore a need for harmonisation in the assessment process.  The Excel based tool HEAT (HELCOM Eutrophication Assessment Tool) has been used in previous assessments in the HELCOM region. There are two versions of the tool; HEAT 1.0 and HEAT 3.0, the first is based on the WFD methodology and the second is based on the MSFD methodology. The main difference between HEAT 1.0 and HEAT 3.0 is how the indicators are grouped. Here we assess the eutrophication status in coastal waters by applying HEAT and compare the results with the national WFD assessments. The present test includes data on 33 selected coastal water bodies in five countries: Estonia, Finland, Latvia, Poland and Sweden. Data on reference condition, acceptable deviation, status and class boundaries of all indicators used in WFD for reporting ecological status (biological and physical-chemical) have been provided for each tested water body. The data has been inserted in the HEAT 1.0 and HEAT 3.0 tools and been compared with the national WFD assessments.  Both HEAT versions gave lower status in more than 50 % of the cases. For some tests the status changed to sub-GES from GES when HEAT is applied. The good/moderate boundary is the same in both HEAT and the WFD while the lower class boundaries in general are stricter in HEAT, which explains the lower status. In national WFD assessments expert judgment is used when there is little, no or very uncertain in situ data. The status in HEAT is given by the one-out-all-out principle but it is still possible to include expert judgment through the weighting factors.

    • Development of an oxygen consumption indicator

    t was investigated if the oxygen consumption can be used as an oxygen indicator for the Baltic Sea. The method is based on the idea of calculating the oxygen consumption in a stabile layer below the productive zone during summer and relating this to nutrient concentrations. With more nutrients available there is an increased biological production. By estimating how much oxygen is needed to mineralise the biological material it may be possible to link the oxygen consumption to eutrophication. The oxygen consumption was calculated for the BY15-Gotland Deep in the Eastern Gotland Basin. We identified a stabile layer between 30 and 50 m and a large change in both oxygen and nutrients from June to August. However, the oxygen consumption had a very high inter-annual variation and there were no significant correlation with the winter mean of nutrient concentrations. It was not possible to calculate the diffusion between the layers because of too sparse measurements at the stratification which limits the method. The calculation of the diffusion is however possible to improve with a model. Further on, the depth of the stabile layer is varying between areas and also between years.  We realised that the method has too many restrictions to be a functional indicator. A functional indicator shall not be dependent on heavy modelling or demand too much on expert judgement. 

    We also investigated if a possible candidate to use as a more simple oxygen consumption indicator could be the use of oxygen saturation at a specific depth. If we assume that the temperature has not changed much since the establishment of stratification we may expect that changes in oxygen saturation observed in August at this depth would be caused by the biological oxygen consumption occurring during late spring and summer. The correlation with winter mean nutrients slightly improved in this case.

  • 2171.
    Wesslander, Karin
    et al.
    SMHI, Core Services.
    Andersson, Lars
    SMHI, Core Services.
    Axe, Philip
    SMHI, Research Department, Oceanography.
    Johansson, Johannes
    SMHI, Core Services.
    Linders, Johanna
    SMHI, Core Services.
    Nexelius, Nils
    SMHI, Core Services.
    Skjevik, Ann-Turi
    SMHI, Core Services.
    Swedish National Report on Eutrophication Status in the Skagerrak, Kattegat and the Sound - OSPAR ASSESSMENT 20162017Report (Other academic)
    Abstract [en]

    The Swedish OSPAR waters were assessed by applying the OSPAR Common Procedure for the time period 2006 – 2014. The Swedish parts of Skagerrak, Kattegat and the Sound constitute the outer part of the transition zone between the estuarine Baltic Sea and the oceanic North Sea and were investigated for nutrients, chlorophyll-a,oxygen, macrophytes, phytoplankton and zoobenthos. The conclusion from the overall assessment of the Swedish OSPAR waters was that only Skagerrak open sea could be classified as a Non-Problem Area and all other assessment units were classified as Problem Areas.  Atmospheric input of nitrogen significantly decreased in both Skagerrak and Kattegat and the land based input of total nutrients also decreased in Skagerrak, Kattegat as well as the Sound. However, the short-term trend of nitrogen input to the Sound was positive. Skagerrak is governed by trans-boundary transports from the North Sea of mainly nitrogen but also phosphorus. Kattegat receives trans-boundary nutrients from both the Baltic Sea through the Sound and from Skagerrak and transports nutrients towards the coast and the western part of the basin.  Overall, concentrations of DIN, DIP, TN and chlorophyll-a decreased in most areas, however, no significant trends were found for DIP. Increasing concentrations were found in silicate, POC and TP. The Secchi depth increased in most areas. Oxygen deficiency was mainly a problem in the fjords and the Kattegat open sea.  In Skagerrak coastal waters winter nutrients were only elevated in the fjords. Concentrations of DIN generally decreased significantly and there were tendencies of decreasing DIP. This pattern was also supported by the total nitrogen while total phosphorus increased. Secchi depth was improving and there was a significant positive trend of increasing depths. However, zoobenthos were still in bad condition and phytoplankton indicator species were often elevated. Chlorophyll-a concentrations were generally decreasing but still elevated in the inner coastal waters. There were also problems with algal toxins such as DST (Diarrhetic Shellfish Toxin) and PST (Paralystic Shellfish Toxin) infections in the area. According to the OSPAR classification scheme, a unit with no evident increased nutrient enrichment can be classified as a Problem Area but the cause might be due to trans-boundary transport from adjacent areas. In the open area of Kattegat there were still problems with oxygen deficiency, especially in the southern parts, even though the trend was significantly positive for the assessment period 2006 – 2014. Concentrations of chlorophyll-a and DIN decreased significantly, however, DIN levels were still generally elevated, especially in the southern parts of Kattegat while DIP was closer to the assessment level. In Kattegat coastal waters winter nutrients were elevated in all assessment units, except from the inner coastal waters, even though there was a general pattern of decreasing going trends. Chlorophyll-a was mainly elevated in the Sound and the estuaries. Secchi depth is generally improving and a significant increase was seen in the Sound. Also in Kattegat, zoobenthos were in bad condition and phytoplankton indicator species were often elevated. 

  • 2172.
    Wesslander, Karin
    et al.
    SMHI, Core Services.
    Viktorsson, Lena
    SMHI, Core Services.
    Summary of the Swedish National Marine Monitoring 2016 - Hydrography, nutrients and phytoplankton2017Report (Other academic)
    Abstract [en]

    Results from the Swedish national marine monitoring in the pelagic during 2016 are presented. The institutes who conduct the national monitoring are SMHI (Swedish meteorological and hydrological institute), SU (Stockholm University) and UMF (Umeå marine sciences centre). The presented parameters in this report are; salinity, temperature, oxygen, dissolved inorganic phosphorous, total phosphorous, dissolved inorganic nitrogen, total nitrogen, dissolved silica, chlorophyll and phytoplankton. Secchi depth, zooplankton, humus, primary production, pH and alkalinity are also measured but not presented. Seasonal plots for surface waters are presented in Appendix I.  Time series for surface waters (0-10 m) and bottom waters are presented in Appendix II. The amount of nutrients in the sub-basins of the Baltic Sea is presented per season and year in Appendix III.Exceptional events 2016 

    • A warm September due to several high pressure systems, with temperatures more than one standard deviation above mean in almost all stations from Skagerrak, Kattegat and the Baltic Proper.
    • Low oxygen in Kattegat bottom water during autumn as can be seen in the seasonal plots for both Anholt E and Fladen.
    • Improved oxygen condition in the East Gotland Basin, due to an increased frequency of deep water inflows in comparison to the period 1983 until the large inflow in December 2014. The inflow of 30 km3 in the beginning of the year could be tracked in the deep water in the Eastern Gotland Basin in June.
    •  Elevated levels of silicate have been observed in the Baltic Sea since 2014 and the silicate levels were also elevated this year but mainly in the central and the northern parts of the Baltic Proper.
    • In July there were high cell numbers of the dinoflagellate Dinophysis acuminata, which caused high levels of toxins in blue mussels. During this period it was forbidden to harvest blue mussels along the Bohus coast.
    • Unusual long period of cyanobacteria bloom in the Baltic Sea.
  • 2173.
    Wesslander, Karin
    et al.
    SMHI, Core Services.
    Viktorsson, Lena
    SMHI, Core Services.
    Fölster, Jens
    Drakare, Stina
    Sonesten, Lars
    Förslag till plan för revidering av fysikalisk-kemiska bedömningsgrunder för ekologisk status i sjöar, vattendrag och kustvatten Del A: SJÖAR OCH VATTENDRAG (SLU) Del B: KUSTVATTEN (SMHI)2017Report (Other academic)
  • 2174.
    Wesslander, Karin
    et al.
    SMHI, Core Services.
    Viktorsson, Lena
    SMHI, Core Services.
    Skjevik, Ann-Turi
    SMHI, Core Services.
    The Swedish National Marine Monitoring Programme 2018. Hydrography Nutrients Phytoplankton2019Report (Other academic)
    Abstract [en]

    This report presents the main results of the Swedish national marine monitoring programme of thepelagic during 2018. The monitoring data of hydrography, nutrients and phytoplankton are analysedfor the seas surrounding Sweden: the Skagerrak, the Kattegat, the Sound, the Baltic Proper, theBothnian Sea and the Bothnian Bay.The national environmental monitoring of the pelagic is carried out by SMHI (SwedishMeteorological and Hydrological Institute), Stockholm University and UMF (Umeå Marine SciencesCentre). Data is collected, analysed and reported with support from Swedish environmentalmonitoring and on behalf of by SwAM (Swedish Agency for Marine and Water Management). TheSMHI monitoring is made in cooperation between the national environmental monitoring of thepelagic and the SMHI oceanographic sampling programme for the seas surrounding Sweden and is cofinancedby SwAM and SMHI. This annual summary of the national monitoring is made by SMHI andis financed by the contract between SwAM and SMHI.The weather in 2018 was characterized by high air temperatures and a few storms that impliedconsequences for the state in the sea. The spring arrived quickly and the sea surface temperatureincreased rapidly from April to May. In August and September two storms, named Johanne and Knud,passed the region and the surface layer was well-mixed at several stations. At the East coast upwellingevents were noted in both the Baltic Proper and the Bothnian Sea.During the year there were two small deep water inflows to the Baltic Proper that temporarilyimproved the oxygen condition in the southern parts. No improvements of the oxygen condition wereseen in the Eastern and Western Gotland Basins, instead the amount of hydrogen sulphide increased inthese basins during the year.The spring bloom had arrived in the Skagerrak and the Kattegat in March and concentrations ofdissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN) were close to or at thedetection limit from April to September. In the Skagerrak and the Kattegat the spring bloom wasdominated by the diatom Skeletonema marinoi. In the Baltic Proper the spring bloom was observed amonth later, in April. The extensive cyanobacteria bloom in the Baltic Proper started already in Mayand during the late September cruise cyanobacteria were still abundant. The dinoflagellateProrocentrum compressum was found in high cell numbers during the autumn at all stations on theWest coast. This flagellate has rarely been observed previously and although it is not harmful it isinteresting when species suddenly occur and stay for a longer period. The potentially harmful diatomgenus Pseudo-nitzschia bloomed in the beginning of December.Surface concentrations of DIP and DIN were mainly normal except from in the Skagerrak and theKattegat where concentrations were lower than usual in December. Concentrations of silicate wereabove normal levels before the spring bloom at most of the stations and in the Baltic Proper silicatewas also high in the autumn.In 2018 there were some difficulties with available research vessels for the planned cruises and somecruises needed to be cancelled with short notice. Many planned observations were therefore missed, inparticular during the summer period.

  • 2175.
    Wesslander, Karin
    et al.
    SMHI, Core Services.
    Viktorsson, Lena
    SMHI, Core Services.
    Skjevik, Ann-Turi
    SMHI, Core Services.
    The SwedishNational MarineMonitoringProgramme 2017: HydrographyNutrientsPhytoplankton2018Report (Other academic)
    Abstract [en]

    This report presents the main results of the Swedish national marine monitoring programme of the pelagic during 2017. The monitoring data of hydrography, nutrients and phytoplankton are analysed for the seas surrounding Sweden: Skagerrak, Kattegat, The Sound, Baltic Proper, Bothnian Sea and Bothnian Bay. The monitoring is carried out by SMHI (Swedish Meteorological and Hydrological Institute), SU (Stockholm University) and UMF (Umeå Marine Sciences Centre) and the monitoring programme is co-funded by SwAM (Swedish Agency for Marine and Water Management), SMHI, SU and UMF. Data is collected, analysed and reported with support from Swedish environmental monitoring and commissioned by SwaM.

    The Baltic current along the Swedish west coast implies large variations in surface salinity and the unusually large outflow of brackish water from the Baltic Sea in 2017 was reflected as low surface salinity in Skagerrak and Kattegat in the beginning of the year. There were no major deep water inflows to the Baltic Sea during 2017 but a few inflows of minor magnitude. These minor inflows only temporarily improved the oxygen condition in the Bornholm Basin and in the southern part of the Eastern Gotland Basin.

    The salinity below the halocline was above normal in the Gotland Basins and in the Northern Baltic Proper, and also in the surface layer in the Eastern Gotland Basin for almost the whole year.

    In Skagerrak and Kattegat, surface concentrations of phosphate and dissolved inorganic nitrogen were normal while dissolved silica concentrations were elevated especially in spring. In the Baltic Sea, the concentration of silicate in the surface water was elevated in all basins. According to the estimated total content of silicate there has been an increase in silica content in the Baltic Sea since the early 1990’s. Surface concentrations of phosphate were above normal in the Gotland basins and the Northern Baltic Proper while inorganic nitrogen content was above normal in parts of the Arkona and Bornholm basins. During spring and summer, the inorganic nitrogen was consumed at greater depths than usual in the Baltic Proper. In particular concentrations of phosphate and dissolved silica were generally lower than normal in the bottom layer.

    Instead of diatoms, the flagellate genus Pseudochattonella, which is potentially toxic to fish, bloomed in the Kattegat and Skagerrak areas in February – April. During autumn there was a prolonged diatom bloom though. In the Baltic Sea spring bloom occurred in April. The cyanobacteria bloom began in May already with Aphanizomenon flos-aquae. During June and July all three of the filamentous cyanobacteria, A. flos-aquae, Dolichospermum lemmermannii and the potentially harmful Nodularia spumigena were found in the phytoplankton samples in various amounts.

    In the Bothnian Sea, the sea surface temperature during summer was lower than normal and the oxygen conditions in the bottom layer was not critical but still below normal levels.

  • 2176. Westra, S.
    et al.
    Fowler, H. J.
    Evans, J. P.
    Alexander, L. V.
    Berg, Peter
    SMHI, Research Department, Climate research - Rossby Centre.
    Johnson, F.
    Kendon, E. J.
    Lenderink, G.
    Roberts, N. M.
    Future changes to the intensity and frequency of short-duration extreme rainfall2014In: Reviews of geophysics, ISSN 8755-1209, E-ISSN 1944-9208, Vol. 52, no 3, p. 522-555Article, review/survey (Refereed)
    Abstract [en]

    Evidence that extreme rainfall intensity is increasing at the global scale has strengthened considerably in recent years. Research now indicates that the greatest increases are likely to occur in short-duration storms lasting less than a day, potentially leading to an increase in the magnitude and frequency of flash floods. This review examines the evidence for subdaily extreme rainfall intensification due to anthropogenic climate change and describes our current physical understanding of the association between subdaily extreme rainfall intensity and atmospheric temperature. We also examine the nature, quality, and quantity of information needed to allow society to adapt successfully to predicted future changes, and discuss the roles of observational and modeling studies in helping us to better understand the physical processes that can influence subdaily extreme rainfall characteristics. We conclude by describing the types of research required to produce a more thorough understanding of the relationships between local-scale thermodynamic effects, large-scale atmospheric circulation, and subdaily extreme rainfall intensity.

  • 2177.
    Westring, Gustaf
    SMHI.
    Brofjordens kraftstation: Kompletterande simulering och analys av kylvattenspridning i Trommekilen1991Report (Other academic)
    Abstract [sv]

    Vattenfall AB planerar att lokalisera ett kraftverk intill Scanraff vid Brofjorden. SMHI i samarbete med Vatten Utveckling AB har av Vattenfall Energisystem AB fått i uppdrag att utreda kylvattenspridningen i området. Utredningen ska belysa om man genom lämpligt val av utsläppsarrangemang kan få en gynnsam uppvärmning av Hanneviken och därigenom förbättra förutsättningarna för en ostronodling norr om Hanneviksholmen, samt var man vintertid ska lokalisera utsläppet för att isbildningen i Hanneviken ska bli så opåverkad som möjligt. Som ett led i utredningen har SMHI tidigare producerat två rapporter.

    Denna nya rapport utförs med delvis nya förutsättningar, baserar sig på en förbättrad numerisk modell och är inriktad på att bestämma hur höga övertemperaturerna vid kylvattenintaget blir. Beräkningarna görs för två kylvattenflöden, 8 och 4 m3/s. Tre alternativa utsläppspunkter prövas: en i Hanneviken (punkt A), en i yttre Trommekilen (punkt D), och en i inre Trommekilen (punkt C) nära kylvattenintaget. Kylvattnet tas från en punkt i inre Trommekilen på 5 meters djup (totalt djup 8 meter). Temperaturhöjningen av kylvattnet genom kraftverket är 1 O °C. Det numeriska modellarbetet utfördes av Bengt Hemström, Vattenfall Utveckling AB, Älvkarleby.

    Utredningens slutsatser är baserade på; hydrografiska mätningar i Brofjorden och Trommekilen/Hanneviken, tidigare SMHI rapporter, jämförelser med mätningar gjorda utanför andra svenska kraftverk, resultatet av det numeriska modellarbetet, och allmän referenslitteratur.

  • 2178.
    Westring, Gustaf
    SMHI.
    Isförhållanden utmed Sveriges kust: Isstatistik från svenska farleder och farvatten under normalperioderna 1931-60 och 1961-901995Report (Other academic)
    Abstract [sv]

    Utgående ifrån isstatistik från svenska farleder och farvatten under normalperioderna 1931-60 och 1961-90 (kapitel 2) har isförhållandena utmed Sveriges kust beskrivits i ord och bild (kapitel 3).

    Någon enklare och meningsfull klassificering av farleder och farvatten har ej kunnat uppnås eftersom isförhållandenas mönster är alltför komplicerat, diffust eller allmängiltigt (kapitel 4). Följande iakttagelser kunde dock göras:

    1. Bottenviken och Norra Kvarken skiljer sig från övriga kustvatten i ett väsentligt avseende - där förekommer is varje år, i de innersta delarna av skärgården såväl som de yttersta vid gränsen till öppet hav.

    2. Kustvattnen mellan Norra Kvarken och Hanöbukten har helt olika iskaraktär, men det är främst utmed denna sträcka som förändringarna sker gradvis, nästan linjärt.

    3. Isförhållandena utmed Hanöbukten, södra Skånekusten och hela Västkusten är inte homogena men de är likartade.

    4. Gotlands kustvatten utgör i många fall undantag från generella trender och skillnaderna mellan ost- och västkust är ofta stora. Detta torde, i alla fall delvis, bero på att ostkusten är långgrund och västkusten brant.

    5. I Öresund och Kalmarsund varierar isförhållandena kraftigt över relativt korta sträckor, nästan lika snabbt som i delar av skärgårdsområdena.  

    Vid jämförelser och analyser av normalperiodernas isstatistik samt annan klimatinformation har det visat sig att isförhållandena i svenska kustvatten har försvårats under perioden 1931-90 och att detta i hög grad sammanhänger med en sänkning av lufttemperaturen i Sverige. Under normalperioden 1961-90 var därför medellängden på isvintrarna fem dagar längre än under normalperioden 1931-60, en ökning med cirka 9 % på 30 år. 

  • 2179.
    Westring, Gustaf
    SMHI.
    Isförhållandena i svenska farvatten under normalperioden 1961-902009Report (Other academic)
    Abstract [sv]

    Denna publikation innehåller statistik över isförhållanden i svenska farvatten från och med vintern 1960/61 till och med vintern 1989/90, totalt 30 vintrar. Materialet är en sammanställning av olika isobservationer huvudsakligen gjorda i viktigare svenska farleder och farvatten. Följaktligen rör statistiken nästan uteslutande farleder i svenska kust- och skärgårdsområden (inklusive Vänern och Mälaren), och i liten utsträckning öppet hav eller områden bortom farledernas omedelbara närhet.

    Resultatet av sammanställningen redovisas i två tabeller (kapitel 4):

    • Tabell 1 innehåller uppgifter om data-underlag, samt normal- och extremvärden för normalperioden.
    • Tabell 2 innehåller beskrivande uppgifter om varje individuell vinter under normalperioden.

    Definitioner och förklaringar till tabellerna 1 och 2 finns i kapitel 4.SMHI har utgivit två föregångare till denna rapport:

    • "Isförhållanden i svenska farvatten under normalperioden 1931 - 1960" av B. Thorslund. SMID, Serie Meteorologi, Nr 13, Stockholm 1966.
    • "Isförhållanden i Vänern under perioden 1940 - 1963" av J-E Lundqvist. SMHI, Serie Meteorologi, Nr 18, Stockholm 1969.

    Dessa två har därför i stor mån styrt utformningen av detta verk. För läsare med intresse för isstatistik gällande öppna hav kring Sverige kan nämnas:

    • "Klimatologisk isatlas för Östersjön, Kattegatt, Skagerrak och Vänern   (1963 -1979)". SMHI, Norrköping Merentutkimuslaitos/ Havsforskningsinstitutet, Helsinki, Finland. Tryckt av SjöfartsverketsTryckeri, Norrköping 1982. 
  • 2180.
    Westring, Gustaf
    SMHI.
    Vågmätningar utanför Kristianopel: Slutrapport1991Report (Other academic)
    Abstract [sv]

    Som ett led i projekteringen av ett havsbaserat vindkraftverk utanför Blekinges Kust, har SMHI fått i uppdrag av EnerGia AB att undersöka vågklimatet utanför Kristianopel. Undersökningen skall speciellt belysa lugna vågperioders frekvens och varaktighet, samt hur höga extremvågor kan vara.

    Analysen av vågklimatet är baserad på: en utanför Kristianopel åt EnerGia utförd nio månaders vågmätning; en av SMHI driven automatstation för vågmätning vid Ölands Södra Grund (1978 - 1991); samt SMHis väder-databas.

    Slutsatserna rör bara området utanför Kristianopel, i vilket den lokala vågmätningen utfördes.

    Lugna vågförhållanden, här definierade som Hs "=' 0.3 meter, förekommer i genomsnitt 30 % av året. På våren och sommaren kan denna siffra stiga till 50 % och på hösten och vintern sjunka till 7 % av tiden. Medel-antalet lugna perioder per månad är 17 stycken, men kan sjunka till 6 på vintern och öka till 30 på sommaren. De längsta lugna perioderna inträffar på sommaren ( i genomsnitt 55 - 65 timmar) och vintern (i genomsnitt cirka 60 timmar). Därför är förutsättningarna för arbete som kräver lugnt väder under en längre period bäst på sommaren (juni - augusti), men även vintern (januari - februari) är bra om isförhållandena tillåter. Längsta uppmätta lugna period var 102 timmar lång. Sett över ett dygn är nätter ofta lugnare än dagar, speciellt sommartid.

    Svåra vågförhållanden (vindhastighet > 13.9 m/ s, dvs kuling eller storm) förekommer i genomsnitt cirka 10 % av året, uppdelad på ungefär 80 tillfällen med en medel-varaktighet på cirka 11 timmar. Längsta uppmätta varaktighet är 6.1 dygn. Maximal tid med kuling/storm under ett år är 1 660 timmar och minimal cirka 500 timmar. På vintern inträffar flest hårdvinds-perioder, i genomsnitt 11 gånger per månad, med en medelvaraktighet på cirka 16 timmar. På sommaren förekommer 5 - 6 hårdvinds-perioder per månad, med en medelvaraktighet på 7 - 8 timmar. Den dominerande vindriktningen vid hårda vindar är året runt SW-W. Hårda vindar kan under november, december, februari och mars också vara vanliga från E-SE, samt under april och maj från NE. Området utanför Kristianopel ligger öppet för vindar från SE-SW.

  • 2181.
    Westring, Gustaf
    et al.
    SMHI.
    Andersson, Jan
    SMHI, Core Services.
    Lindh, Henrik
    SMHI, Core Services.
    Axelsson, Robert
    SMHI.
    Forsmark - en temperaturstudie: Slutrapport1993Report (Other academic)
    Abstract [sv]

    Om inget annat nämns refererar alla uppgifter i detta kapitel till station 126 som antas vara representativ för hela fjärden däromkring. Begreppen yta och botten, i samband med referenser till temperaturskillnader, är egentligen baserade på mätningar vid 1.5 respektive 16 m djup, men de ger realistiska mått på hur mycket kallare kylvattnet normalt kommer att vara om det hämtas ur djupvattnet vid station 126.

    Temperaturskillnaden mellan ytan och botten under sommaren (andra hälften av juni till och med augusti) ligger normalt kring 3 °C. Under våren är differensen betydligt större och från och med september då hösten normalt inträtt råder nästan isotermi. Temperaturskillnaden för ytan - 12 m och ytan - 8 m djup är under sommaren normalt cirka 2 respektive 1 °C. För närmare detaljer om fördelningen av temperaturskillnaderna mellan ytan och olika djup har kumulativa frekvensdiagram framtagits.

    Temperaturdifferensen styrs under sommaren av vindens riktning, styrka och varaktighet. I viss mån spelar också tröskeldjupet till fjärden en roll. Starkare nordliga vindar under cirka två dygn leder till perioder med små temperatur- killnader, dessa varar normalt 2 - 3 dygn. Sydliga vindar av måttlig styrka under 2 - 3 dygn eller mer leder till kraftiga temperaturdifferenser. Perioder med mycket svaga vindar leder till en höjning av temperaturskillnaden. Sydliga vindar förekommer cirka 50 % av sommaren, mycket svaga vindar cirka 15 %.

    I sektion 4.7 finns en välmenad lekmanslista på aspekter som bör ägnas speciell uppmärksamhet i det fortsatta arbetet med att sänka kylvattnets intagstemperatur under sommaren.

  • 2182.
    Westring, Gustaf
    et al.
    SMHI.
    Wickström, Kjell
    SMHI.
    Spridningsberäkningar för Höganäs kommun1990Report (Other academic)
  • 2183.
    Wetterhall, Fredrik
    et al.
    SMHI, Research Department, Hydrology.
    Bardossy, Andras
    Chen, Deliang
    Halldin, Sven
    Xu, Chong-Yu
    Daily precipitation-downscaling techniques in three Chinese regions2006In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 42, no 11, article id W11423Article in journal (Refereed)
    Abstract [en]

    [ 1] Four methods of statistical downscaling of daily precipitation were evaluated on three catchments located in southern, eastern, and central China. The evaluation focused on seasonal variation of statistical properties of precipitation and indices describing the precipitation regime, e. g., maximum length of dry spell and maximum 5-day precipitation, as well as interannual and intra-annual variations of precipitation. The predictors used in this study were mean sea level pressure, geopotential heights at 1000, 850, 700, and 500 hPa, and specific humidity as well as horizontal winds at 850, 700, and 500 hPa levels from the NCEP/NCAR reanalysis with 2.5 degrees x 2.5 degrees resolution for 1961 - 2000. The predictand was daily precipitation from 13 stations. Two analogue methods, one using principal components analysis (PCA) and the other Teweles-Wobus scores (TWS), a multiregression technique with a weather generator producing precipitation (SDSM) and a fuzzy-rule-based weather-pattern-classification method (MOFRBC), were used. Temporal and spatial properties of the predictors were carefully evaluated to derive the optimum setting for each method, and MOFRBC and SDSM were implemented in two modes, with and without humidity as predictor. The results showed that ( 1) precipitation was most successfully downscaled in the southern and eastern catchments located close to the coast, ( 2) winter properties were generally better downscaled, ( 3) MOFRBC and SDSM performed overall better than the analogue methods, ( 4) the modeled interannual variation in precipitation was improved when humidity was added to the predictor set, and ( 5), the annual precipitation cycle was well captured with all methods.

  • 2184.
    Wetterhall, Fredrik
    et al.
    SMHI, Research Department, Hydrology.
    Bardossy, Andras
    Chen, Deliang
    Halldin, Sven
    Xu, Chong-yu
    Statistical downscaling of daily precipitation over Sweden using GCM output2009In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 96, no 1-2, p. 95-103Article in journal (Refereed)
    Abstract [en]

    A classification of Swedish weather patterns (SWP) was developed by applying a multi-objective fuzzy-rule-based classification method (MOFRBC) to large-scale-circulation predictors in the context of statistical downscaling of daily precipitation at the station level. The predictor data was mean sea level pressure (MSLP) and geopotential heights at 850 (H850) and 700 hPa (H700) from the NCEP/NCAR reanalysis and from the HadAM3 GCM. The MOFRBC was used to evaluate effects of two future climate scenarios (A2 and B2) on precipitation patterns on two regions in south-central and northern Sweden. The precipitation series were generated with a stochastic, autoregressive model conditioned on SWP. H850 was found to be the optimum predictor for SWP, and SWP could be used instead of local classifications with little information lost. The results in the climate projection indicated an increase in maximum 5-day precipitation and precipitation amount on a wet day for the scenarios A2 and B2 for the period 2070-2100 compared to 1961-1990. The relative increase was largest in the northern region and could be attributed to an increase in the specific humidity rather than to changes in the circulation patterns.

  • 2185.
    Wetterhall, Fredrik
    et al.
    SMHI, Research Department, Hydrology.
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Andreasson, Johan
    SMHI, Professional Services.
    Rosberg, Jörgen
    SMHI, Research Department, Hydrology.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Using ensemble climate projections to assess probabilistic hydrological change in the Nordic region2011In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 11, no 8, p. 2295-2306Article in journal (Refereed)
    Abstract [en]

    Assessing hydrological effects of global climate change at local scales is important for evaluating future hazards to society. However, applying climate model projections to local impact models can be difficult as outcomes can vary considerably between different climate models, and including results from many models is demanding. This study combines multiple climate model outputs with hydrological impact modelling through the use of response surfaces. Response surfaces represent the sensitivity of the impact model to incremental changes in climate variables and show probabilies for reaching a priori determined thresholds. Response surfaces were calculated using the HBV hydrological model for three basins in Sweden. An ensemble of future climate projections was then superimposed onto each response surface, producing a probability estimate for exceeding the threshold being evaluated. Site specific impacts thresholds were used where applicable. Probabilistic trends for future change in hazards or potential can be shown and evaluated. It is particularly useful for visualising the range of probable outcomes from climate models and can easily be updated with new results as they are made available.

  • 2186.
    Wetterhall, Fredrik
    et al.
    SMHI, Research Department, Hydrology.
    Pappenberger, F.
    Alfieri, L.
    Cloke, H. L.
    Thielen-del Pozo, J.
    Balabanova, S.
    Danhelka, J.
    Vogelbacher, A.
    Salamon, P.
    Carrasco, I.
    Cabrera-Tordera, A. J.
    Corzo-Toscano, M.
    Garcia-Padilla, M.
    Garcia-Sanchez, R. J.
    Ardilouze, C.
    Jurela, S.
    Terek, B.
    Csik, A.
    Casey, J.
    Stankunavicius, G.
    Ceres, V.
    Sprokkereef, E.
    Stam, J.
    Anghel, E.
    Vladikovic, D.
    Eklund, C. Alionte
    Hjerdt, N.
    Djerv, H.
    Holmberg, F.
    Nilsson, J.
    Nystrom, K.
    Susnik, M.
    Hazlinger, M.
    Holubecka, M.
    HESS Opinions "Forecaster priorities for improving probabilistic flood forecasts"2013In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 17, no 11, p. 4389-4399Article in journal (Refereed)
    Abstract [en]

    Hydrological ensemble prediction systems (HEPS) have in recent years been increasingly used for the operational forecasting of floods by European hydrometeorological agencies. The most obvious advantage of HEPS is that more of the uncertainty in the modelling system can be assessed. In addition, ensemble prediction systems generally have better skill than deterministic systems both in the terms of the mean forecast performance and the potential forecasting of extreme events. Research efforts have so far mostly been devoted to the improvement of the physical and technical aspects of the model systems, such as increased resolution in time and space and better description of physical processes. Developments like these are certainly needed; however, in this paper we argue that there are other areas of HEPS that need urgent attention. This was also the result from a group exercise and a survey conducted to operational forecasters within the European Flood Awareness System (EFAS) to identify the top priorities of improvement regarding their own system. They turned out to span a range of areas, the most popular being to include verification of an assessment of past forecast performance, a multi-model approach for hydrological modelling, to increase the forecast skill on the medium range (> 3 days) and more focus on education and training on the interpretation of forecasts. In light of limited resources, we suggest a simple model to classify the identified priorities in terms of their cost and complexity to decide in which order to tackle them. This model is then used to create an action plan of short-, medium-and long-term research priorities with the ultimate goal of an optimal improvement of EFAS in particular and to spur the development of operational HEPS in general.

  • 2187. Weyhenmeyer, Gesa A.
    et al.
    Froberg, Mats
    Karltun, Erik
    Khalili, Maria
    Kothawala, Dolly
    Temnerud, Johan
    SMHI, Research Department, Hydrology.
    Tranvik, Lars J.
    Selective decay of terrestrial organic carbon during transport from land to sea2012In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 18, no 1, p. 349-355Article in journal (Refereed)
    Abstract [en]

    Numerous studies have estimated carbon exchanges at the landatmosphere interface, more recently also including estimates at the freshwateratmosphere interface. Less attention has been paid to lateral carbon fluxes, in particular to the fate of terrestrial carbon during transport from soils via surface waters to the sea. Using extensive datasets on soil, lake and river mouth chemistry of the boreal/hemiboreal region we determined organic carbon (OC) stocks of the O horizon from catchment soils, annual OC transports through more than 700 lakes (OClakeflux) and the total annual OC transport at Sweden's 53 river mouths (OCseaflux). We show here that a minimum of 0.030.87% yr(-1) of the OC soil stocks need to be exported to lakes in order to sustain the annual OClakeflux. Across Sweden we estimated a total OClakeflux of similar to 2.9 Mtonne yr(-1), which corresponds to similar to 10% of Sweden's total terrestrial net ecosystem production, and it is over 50% higher than the total OCseaflux. The OC loss during transport to the sea follows a simple exponential decay with an OC half-life of similar to 12 years. Water colour, a proxy often used for dissolved humic matter, is similarly lost exponentially but about twice as fast as OC. Thus, we found a selective loss of the coloured portion of soil-derived OC during its transport through inland waters, prior to being discharged into the sea. The selective loss is water residence time dependent, resulting in that the faster the water flows through the landscape the less OC and colour is lost. We conclude that increases in runoff will result in less efficient losses of OC, and particularly of colour, if the time for OC transformations in the landscape shortens. Consequently, OC reaching the sea is likely to become more coloured, and less processed, which can have far-reaching effects on biogeochemical cycles.

  • 2188. White, Christopher J.
    et al.
    Carlsen, Henrik
    Robertson, Andrew W.
    Klein, Richard J. T.
    Lazo, Jeffrey K.
    Kumar, Arun
    Vitart, Frederic
    de Perez, Erin Coughlan
    Ray, Andrea J.
    Murray, Virginia
    Bharwani, Sukaina
    MacLeod, Dave
    James, Rachel
    Fleming, Lora
    Morse, Andrew P.
    Eggen, Bernd
    Graham, Richard
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Becker, Emily
    Pegion, Kathleen V.
    Holbrook, Neil J.
    McEvoy, Darryn
    Depledge, Michael
    Perkins-Kirkpatrick, Sarah
    Brown, Timothy J.
    Street, Roger
    Jones, Lindsey
    Remenyi, Tomas A.
    Hodgson-Johnston, Indi
    Buontempo, Carlo
    Lamb, Rob
    Meinke, Holger
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Zebiak, Stephen E.
    Potential applications of subseasonal-to-seasonal (S2S) predictions2017In: Meteorological Applications, ISSN 1350-4827, E-ISSN 1469-8080, Vol. 24, no 3, p. 315-325Article in journal (Refereed)
  • 2189. Wibig, Joanna
    et al.
    Maraun, Douglas
    Benestad, Rasmus
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Lorenz, Philip
    Christensen, Ole Bossing
    Projected Change-Models and Methodology2015Chapter in book (Other academic)
    Abstract [en]

    General (global) circulation models (GCMs) are a useful tool for studying how climate may change in the future. Although GCMs have high temporal resolution, their spatial resolution is low. To simulate the future climate of the Baltic Sea region, it is necessary to downscale GCM data. This chapter describes the two conceptually different ways of downscaling: regional climate models (RCMs) nested in GCMs and using empirical and/or statistical relations between large-scale variables from GCMs and small-scale variables. There are many uncertainties in climate models, including uncertainty related to future land use and atmospheric greenhouse gas concentrations, limits on the amount of input data and their accuracy, and the chaotic nature of weather. The skill of methods for describing regional climate futures is also limited by natural climate variability. For the Baltic Sea area, the lack of an oceanic component in RCMs and poor representation of forcing by aerosols and changes in land use are major limitations.

  • 2190.
    Wickström, Kjell
    SMHI.
    Bedömning av kylvattenrecipienten för ett kolkraftverk vid Oskarshamnsverket1987Report (Other academic)
    Abstract [sv]

    Utsläppet av 18 m3 /s kylvatten från det planerade kolkraftverket ger en ca 20 procentig förstoring av det nu kylvattenpåverkade området.

    Vid utsläpp från Stora Båden kommer området norrut längs Ävrö att påverkas av något högre övertemperaturer, både i ytan och på djupare nivåer, se fig. 3 och 4, än om det släpps ut via Hamnefjärden. Ett utsläpp i Hamnefjärden integrerat med utsläppen från kärnkraftverket ger samma spridningssätt och spridningsväg som tidigare kartläggningar visat.

    Vid utsläpp av kylvatten i Borholmsfjärden ger ett utsläpp på 4.5 m3 Is en påverkan på hela fjärden. Isotermen för övertemperaturen 1 °c täcker en yta av 50-75% av fjärden.

    Vintertid blir ytvattenplymerna större. Då ligger även stora delar av Norre fjärd inom området för 1 °c övertemperatur.

    SMHI föreslår att utsläpp av kylvatten sker enligt alternativ 1. När det gäller reservutsläpp i Borholmsfjärden bör inte mer än 4.5 m3 /s släppas där. Detta om man vill begränsa avkylningsområdet till Borholmsfjärden och Norre fjärd.

  • 2191.
    Wickström, Kjell
    SMHI.
    Oskarshamnsverket - kylvattenutsläpp i havet: Slutrapport1990Report (Other academic)
  • 2192.
    Wickström, Kjell
    SMHI.
    Vågdata från svenska kustvatten 19861988Report (Other academic)
    Abstract [sv]

    Under hösten 1978 startade SMHI med medel från Nämnden för Energiproduktionsforskning registrering av vindgenererade vågor i svenska kustvatten. SMHI har tidigar presenterat vågdata från åren 1978 - 1985. Denna rapport redovisar vågklimatdata för år 1986. Registreringarna görs med två typer av instrument. I närheten av fasta kassunfyrar används bottenfasta ekolod, som flera gånger per sekund mäter avståndet botten - vattenytan. Via kabel går data till en microprocessor (automatstation) i kassunfyren, där viss bearbetning av våguppgifter sker. Vågdata går därefter på telefonlinje till SMHls dator i Norrköping, där nya våguppgifter varje timma kan avläsas på en bildskärm.

    På platser, där kabelförbindelse till en automatstation skulle bli alltför lång, mäts vågorna med en accelerometerboj (wave rider) på ytan. Bojen sänder på radio in våguppgifter till en närbelägen automatstation.

    Fasta stationer med ekolod finns nu på fyrarna Almagrundet, Gustav Dalen Ölands Södra Grund och Trubaduren Svenska Björn är en kassunfyr där ett svensk finskt sammarbete har resulterat i en lång mätserie med en finsk accelerometerboj och mottagningsstation i en av SMHl:s automatstationer. Accelerometerboj har också använts under perioder, 6-12 månader långa, vid Väderöarna, Hoburgen och i Laholmsbukten. Under 1986 har accelerometerbojar använts vid östergarn och Väderöarna.

    Energiforskningsnämnden och SMHI har gemensamt finansierat vågmätningar och bearbetning.

  • 2193.
    Wickström, Kjell
    et al.
    SMHI.
    Hillgren, Robert
    SMHI, Core Services.
    Spridningsberäkningar för EKA-NOBELs fabrik i Stockviksverken1990Report (Other academic)
    Abstract [sv]

    SMHI har på uppdrag av Casco Nobel AB utfört spridningsundersökningar i Sundsvallsbukten för att klarlägga spridningen av natriumklarat från EKA Nobels fabrik i Stockviksverken.

    Vi har valt att kombinera resultaten från strömmätningar och en tredimensionell numerisk modell för att beskriva några typiska strömningsmönster för utsläppsområdet.

    De olika spridningssituationerna som förekommer vid nordlig och sydlig vind samt under islagd tid beskriver cirka 90 procent av alla möjliga situationer.

    För att verifiera modell- och beräkningsresultaten har spårämnesundersökningar genomförts under två dagar. Samtidigt har ström- och skiktningsförhållanden kontrollerats.

    Av resultaten framgår att spridningen av avloppsvattnet sker till övervägande del i ytvattnet och är koncentrerat till området innanför linjen. Essvikslandets norra udde och Alnöns sydvästra hörn. Avloppsvattnet når framförallt strandzonen kring Essvikslandets norra del. Utspädningen av avloppsvattnet ger dock förhållandevis låga koncentrationer (cirka 0,01 ug/1).

  • 2194. Widmann, Martin
    et al.
    Bedia, Joaquin
    Gutierrez, Jose M.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Hertig, Elke
    Maraun, Douglas
    Casado, Maria J.
    Ramos, Petra
    Cardoso, Rita M.
    Soares, Pedro M. M.
    Ribalaygua, Jamie
    Page, Christian
    Fischer, Andreas M.
    Herrera, Sixto
    Huth, Radan
    Validation of spatial variability in downscaling results from the VALUE perfect predictor experiment2019In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 39, no 9, p. 3819-3845Article in journal (Refereed)
  • 2195.
    Wilcke, Renate
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Selecting regional climate scenarios for impact modelling studies2016In: Environmental Modelling & Software, ISSN 1364-8152, E-ISSN 1873-6726, Vol. 78, p. 191-201Article in journal (Refereed)
    Abstract [en]

    In climate change research ensembles of climate simulations are produced in an attempt to cover the uncertainty in future projections. Many climate change impact studies face difficulties using the full number of simulations available, and therefore often only subsets are used. Until now such subsets were chosen based on their representation of temperature change or by accessibility of the simulations. By using more specific information about the needs of the impact study as guidance for the clustering of simulations, the subset fits the purpose of climate change impact research more appropriately. Here, the sensitivity of such a procedure is explored, particularly with regard to the use of different climate variables, seasons, and regions in Europe. While temperature dominates the clustering, the resulting selection is influenced by all variables, leading to the conclusion that different subsets fit different impact studies best. (C) 2016 The Authors. Published by Elsevier Ltd.

  • 2196. Wilk, J.
    et al.
    Andersson, Lotta
    SMHI, Core Services. SMHI, Research Department, Hydrology.
    Graham, Phil
    SMHI, Professional Services.
    Wikner, J. J.
    Mokwatlo, S.
    Petja, B.
    From forecasts to action - What is needed to make seasonal forecasts useful for South African smallholder farmers?2017In: International Journal of Disaster Risk Reduction, E-ISSN 2212-4209, Vol. 25, p. 202-211Article in journal (Refereed)
  • 2197.
    Wilk, Julie
    et al.
    SMHI, Research Department, Hydrology.
    Andersson, Lotta
    SMHI, Core Services.
    Warburton, Michele
    Adaptation to climate change and other stressors among commercial and small-scale South African farmers2013In: Regional Environmental Change, ISSN 1436-3798, E-ISSN 1436-378X, Vol. 13, no 2, p. 273-286Article in journal (Refereed)
    Abstract [en]

    Commercial and small-scale farmers in South Africa are exposed to many challenges. Interviews with 44 farmers in the upper Thukela basin, KwaZulu-Natal, were conducted to identify common and specific challenges for the two groups and adaptive strategies for dealing with the effects of climate and other stressors. This work was conducted as part of a larger participatory project with local stakeholders to develop a local adaptation plan for coping with climate variability and change. Although many challenges related to exposure to climate variability and change, weak agricultural policies, limited governmental support, and theft were common to both farming communities, their adaptive capacities were vastly different. Small-scale farmers were more vulnerable due to difficulties to finance the high input costs of improved seed varieties and implements, limited access to knowledge and agricultural techniques for water and soil conservation and limited customs of long-term planning. In addition to temperature and drought-related challenges, small-scale farmers were concerned about soil erosion, water logging and livestock diseases, challenges for which the commercial farmers already had efficient adaptation strategies in place. The major obstacle hindering commercial farmers with future planning was the lack of clear directives from the government, for example, with regard to issuing of water licences and land reform. Enabling agricultural communities to procure sustainable livelihoods requires implementation of strategies that address the common and specific challenges and strengthen the adaptive capacity of both commercial and small-scale farmers. Identified ways forward include knowledge transfer within and across farming communities, clear governmental directives and targeted locally adapted finance programmes.

  • 2198. Wilk, Julie
    et al.
    Hjerpe, Mattias
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Fan, Hua
    Farm-scale adaptation under extreme climate and rapid economic transition2015In: Environment, Development and Sustainability, ISSN 1387-585X, E-ISSN 1573-2975, Vol. 17, no 3, p. 393-407Article in journal (Refereed)
    Abstract [en]

    This paper aims to analyse what shapes farmers' vulnerability and adaptation strategies in the context of rapid change. Xinjiang is semi-arid, with extremes of temperature, growing seasons and winds. Favourable socioeconomic conditions have boosted the wellbeing of farmers in the past decades. Interviews with forty-seven farmers led to the categorization of five groups according to the predominant type of farming activity: animal farmers, government farmers (leasing land from the Xinjiang Production and Construction Group), crop farmers, agri-tourism operators and entrepreneurs. High government support has aided farmers to deal with climate challenges, through advanced technology, subsidies and loans. Farmers, however, greatly contribute to their own high adaptive capacity through inventiveness, flexibility and a high knowledge base. Although the future climate will entail hotter temperatures, farmers can be seen as generally well equipped to deal with these challenges because of the high adaptive capacity they currently have and utilize. Those that are most vulnerable are those that have difficulty to access credit e.g. animal farmers and those that do not want to change their agricultural systems e.g. from pastoral lifestyles to include tourism-based operations.

  • 2199.
    Wilk, Julie
    et al.
    SMHI, Research Department, Hydrology.
    Jonsson, Anna
    SMHI, Core Services.
    Rydhagen, Birgitta
    Rani, Ashu
    Kumar, Arun
    The perspectives of the urban poor in climate vulnerability assessments - The case of Kota, India2018In: Urban Climate, ISSN 2212-0955, E-ISSN 2212-0955, Vol. 24, p. 633-642Article in journal (Refereed)
  • 2200. Wilk, Julie
    et al.
    Kniveton, Dominic
    Andersson, Lotta
    SMHI, Core Services.
    Layberry, Russell
    Todd, Martin C.
    Hughes, Denis
    Ringrose, Susan
    Vanderpost, Cornelis
    Estimating rainfall and water balance over the Okavango River Basin for hydrological applications2006In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 331, no 1-2, p. 18-29Article in journal (Refereed)
    Abstract [en]

    A historical database for use in rainfall-runoff modeling of the Okavango River Basin in Southwest Africa is presented. The work has relevance for similar data-sparse regions. The parameters of main concern are rainfall and catchment water balance, which are key variables for subsequent studies of the hydrological impacts of development and climate change. Rainfall estimates are based on a combination of in situ gauges and satellite sources. Rain gauge measurements are most extensive from 1955 to 1972, after which they are drastically reduced due to the Angolan civil war. The sensitivity of the rainfall fields to spatial interpolation techniques and the density of gauges were evaluated. Satellite based rainfall estimates for the basin are developed for the period from 1991 onwards, based on the Tropical Rainfall Measuring Mission (TRMM) and Special Sensor Microwave Imager (SSM/I) datasets. The consistency between the gauges and satellite estimates was considered. A methodology was developed to allow calibration of the rainfall-runoff hydrological model against rain gauge data from 1960 to 1972, with the prerequisite that the model should be driven by satellite derived rainfall products from ` 1990 onwards. With the rain gauge data, addition of a single rainfall station (Longa) in regions where stations earlier were lacking was more important than the chosen interpolation method. Comparison of satellite and gauge rainfall outside the basin indicated that the satellite overestimates rainfall by 20%. A non-linear correction was derived by fitting the rainfall frequency characteristics to those of the historical rainfall data. This satellite rainfall dataset was found satisfactory when using the Pitman rainfall-runoff model (Hughes, D., Andersson, L., Wilk, J., Savenije, H.H.G., this issue. Regional calibration of the Pitman model for the Okavango River. Journal of Hydrology). Intensive monitoring in the region is recommended to increase accuracy of the comprehensive satellite rainfall estimate calibration procedure. (c) 2006 Elsevier B.V. All rights reserved.

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