Sökning: "YR Su"

Visar resultat 11 - 15 av 20 avhandlingar innehållade orden YR Su.

1. 11. Holocene climate and atmospheric circulation changes in northern Fennoscandia : Interpretations from lacustrine oxygen isotope records

   Författare :Christina E. Jonsson; Gunhild Rosqvist; Jan Seibert; Philip Barker; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; oxygen isotope; diatom silica; lake sediment; atmospheric circulation; North Atlantic Oscillation; northern Fennoscandia; The Holocene; Little Ice Age; Physical geography; Naturgeografi; Physical Geography; naturgeografi;

   Sammanfattning : This thesis investigates how variations in the oxygen isotopic composition of lake waters in northern Fennoscandia are recorded in lake sediment archives, especially diatoms, and how these variations can be used to infer past changes in climate and atmospheric circulation. Results from analyses of the oxygen isotopic composition of lake water samples (δ18Olakew) collected between 2001 and 2006 show that δ18O of northern Fennoscandian lakes is mainly controlled by the isotopic composition of the precipitation (δ18Op). LÄS MER

3. 12. The colour of climate : A study of raised bogs in south-central Sweden

   Författare :Anders Borgmark; Stefan Wastegård; Ann-Marie Robertsson; Bas van Geel; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Holocene; south-central Sweden; peat humification; bog hydrology; climate variation; spectral analysis; Quaternary geology; Kvartärgeologi;

   Sammanfattning : This thesis focuses on responses in raised bogs to changes in the effective humidity during the Holocene. Raised bogs are terrestrial deposits that can provide contiguous records of past climate changes. Information on and knowledge about past changes in climate is crucial for our understanding of natural climate variability. LÄS MER

4. 13. Transport of mineral dust into the Arctic : Evaluation of two reanalysis datasets of atmospheric composition

   Författare :Sebastian Böö; Annica M. L. Ekman; Adam Kristensson; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Arktis; transport; damm; återanalys; reanalys; aerosol; meteorologi; Meteorology;

   Sammanfattning : The main purpose of this thesis is to examine the mineral dust aerosol transport into the Arctic. Two three-dimensional reanalysis datasets of atmospheric composition, the Copernicus Atmosphere Monitoring Service reanalysis (CAMSRA) and the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), are analyzed with regard to dust transport into the Arctic. LÄS MER

5. 14. Transport, degradation and burial of organic matter released from permafrost to the East Siberian Arctic Shelf

   Författare :Lisa-Marie Bröder; Örjan Gustafsson; Tommaso Tesi; Elizabeth Canuel; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; organic carbon; marine sediments; East Siberian Sea; Laptev Sea; cross-shelf transport; degradation rate constants; carbon isotopes; terrestrial biomarkers; HMW wax lipids; lignin phenols; compound-specific radiocarbon analysis; Applied Environmental Science; tillämpad miljövetenskap;

   Sammanfattning : Permafrost soils in the Arctic store large quantities of organic matter, roughly twice the amount of carbon that was present in the atmosphere before the industrial revolution. This freeze-locked carbon pool is susceptible to thawing caused by amplified global warming at high latitudes. LÄS MER

7. 15. Late Holocene humidity variability in central Sweden

   Författare :Sofia Andersson; Stefan Wastegård; Gunhild Rosqvist; Kristian Schoning; Frank Chambers; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; humidity change; stable isotopes; Chara spp; Pisidium spp; testate amoebae assemblages; humification; C N ratio; late Holocene; central Sweden; Quaternary geology; Kvartärgeologi; kvartärgeologi; Quarternary Geology;

   Sammanfattning : The aim of this thesis was to reconstruct humidity variability in central Sweden during the late Holocene. A multi-proxy approach was used to infer humidity changes as recorded in a lake and a mire. Age-models were constructed based on radiocarbon dating and the Askja-1875 tephra. LÄS MER