Sökning: "varve"

Visar resultat 1 - 5 av 16 avhandlingar innehållade ordet varve.

  1. 1. Climatic signals and frequencies in the Swedish Time Scale, River Ångermanälven, Central Sweden

    Författare :Mikkel Sander; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; marklära; kartografi; klimatologi; pedology; cartography; climatology; Fysisk geografi; geomorfologi; geomorphology; Physical geography; winter precipitation; climate change; central Sweden; last 2000 year; discharge; varve;

    Sammanfattning : Any future climate variation forced by human activities will be superimposed on the background of natural climate variation. Therefore, before interpreting the present climate and addressing future climate scenarios some knowledge of past climate is necessary. LÄS MER

  3. 2. Setting the Holocene clock using varved lake sediments in Sweden

    Författare :Lovisa Zillén; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; climate change; Physical geography; tephrochronology; palaeomagnetic secular variations; radiocarbon time-scale; Holocene varved lake sediments; varve chronology; geomorphology; pedology; cartography; climatology; Fysisk geografi; geomorfologi; marklära; kartografi; klimatologi;

    Sammanfattning : The aim of this thesis was to study annually laminated (varved) Holocene lake sediment in Sweden, their formation and their potential as chronological and palaeoecological archives. Five lakes with continuous Holocene varved lake sediment sequences in northern (Västerbotten) and west central Sweden (Värmland) were investigated. LÄS MER

  4. 3. Varved lake sediments and diagenetic processes

    Författare :Veronika Gälman; Ingemar Renberg; Daniel Conley; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Varved annually laminated lake sediment; diagenesis; varve appearance; iron; sulfur; chemical speciation; iron cycling; carbon; nitrogen; stabile isotopes; δ13C; δ15N; Earth sciences; Geovetenskap;

    Sammanfattning : Varved (annually laminated) sediments are of great interest for inference of past environmental conditions, as they provide dated records with high time resolution. After deposition, the sediment varves are affected by diagenesis; i.e., chemical, physical and biological changes that occur within the sediment. LÄS MER

  5. 4. Testing for Periodicity and Trend in Long-Memory Processes

    Författare :Abdullah Almasri; Statistiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Statistics; temperature data.; sunspots data; wind speed data; varve data; Siegel’s test; Fisher’s test; periodogram; Fractional difference process; Discrete wavelet transform; operations research; programming; actuarial mathematics; Statistik; operationsanalys; programmering; aktuariematematik; Wavelets; Statistik;

    Sammanfattning : This thesis presents methods of testing the periodicity and trend for the time series, which exhibit dependence over long periods of time. Many such processes can be modeled by a class of models called fractionally differenced processes. LÄS MER

  7. 5. Combining limnology and paleolimnology : a refined understanding of environmental sediment signal formation in a varved lake

    Författare :Dominique Béatrice Maier; Christian Bigler; Sebastian Diehl; Jasmine E. Saros; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; varved lake sediments; diatom sediment signal formation; sequential sediment trap; seasonal process timing; ice thinning; varve compaction; climate impact; catchment properties; Earth Sciences with Specialization Environmental Analysis; geovetenskap med inriktning mot miljöanalys;

    Sammanfattning : Paleoclimatic archives, such as lake sediments, extend our understanding of terrestrial and aquatic ecosystem dynamics in relation to climate variability beyond the period covered by instrumental data. In this context, annually laminated (i.e. LÄS MER