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  • 1.
    Dahlke, Helen E.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Lyon, Steve W.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Karlin, Torbjörn
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Rosqvist, Gunhild
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Isotopic investigation of runoff generation in a glacierized catchment in northern Sweden2014In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, no 3, 1383-1398 p.Article in journal (Refereed)
    Abstract [en]

    In this study, summer rainfall contributions to streamflow were quantified in the sub-arctic, 30% glacierized Tarfala (21.7km(2)) catchment in northern Sweden for two non-consecutive summer sampling seasons (2004 and 2011). We used two-component hydrograph separation along with isotope ratios (O-18 and D) of rainwater and daily streamwater samplings to estimate relative fraction and uncertainties (because of laboratory instrumentation, temporal variability and spatial gradients) of source water contributions. We hypothesized that the glacier influence on how rainfall becomes runoff is temporally variable and largely dependent on a combination of the timing of decreasing snow cover on glaciers and the relative moisture storage condition within the catchment. The results indicate that the majority of storm runoff was dominated by pre-event water. However, the average event water contribution during storm events differed slightly between both years with 11% reached in 2004 and 22% in 2011. Event water contributions to runoff generally increased over 2011 the sampling season in both the main stream of Tarfala catchment and in the two pro-glacial streams that drain Storglaciaren (the largest glacier in Tarfala catchment covering 2.9km(2)). We credit both the inter-annual and intra-annual differences in event water contributions to large rainfall events late in the summer melt season, low glacier snow cover and elevated soil moisture due to large antecedent precipitation. Together amplification of these two mechanisms under a warming climate might influence the timing and magnitude of floods, the sediment budget and nutrient cycling in glacierized catchments.

  • 2. Fujita, S.
    et al.
    Holmlund, Per
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Andersson, I.
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Enomoto, H.
    Fujii, Y.
    Fujita, K.
    Fukui, K.
    Furukawa, T.
    Hansson, M.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hara, K.
    Hoshina, Y.
    Igarashi, M.
    Iizuka, Y.
    Imura, S.
    Ingvander, Susanne
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Karlin, Torbjörn
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Motoyama, H.
    Nakazawa, F.
    Oerter, H.
    Sjöberg, L. E.
    Sugiyama, S.
    Surdyk, S.
    Ström, Johan
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Uemura, R.
    Wilhelms, F.
    Spatial and temporal variability of snow accumulation rate on the East Antarctic ice divide between Dome Fuji and EPICA DML2011In: The Cryosphere, ISSN 1994-0416, E-ISSN 1994-0424, Vol. 5, no 4, 1057-1081 p.Article in journal (Refereed)
    Abstract [en]

    To better understand the spatio-temporal variability of the glaciological environment in Dronning Maud Land (DML), East Antarctica, a 2800-km-long Japanese-Swedish traverse was carried out. The route includes ice divides between two ice-coring sites at Dome Fuji and EPICA DML. We determined the surface mass balance (SMB) averaged over various time scales in the late Holocene based on studies of snow pits and firn cores, in addition to radar data. We find that the large-scale distribution of the SMB depends on the surface elevation and continentality, and that the SMB differs between the windward and leeward sides of ice divides for strong-wind events. We suggest that the SMB is highly influenced by interactions between the large-scale surface topography of ice divides and the wind field of strong-wind events that are often associated with high-precipitation events. Local variations in the SMB are governed by the local surface topography, which is influenced by the bedrock topography. In the eastern part of DML, the accumulation rate in the second half of the 20th century is found to be higher by similar to 15% than averages over longer periods of 722 a or 7.9 ka before AD 2008. A similar increasing trend has been reported for many inland plateau sites in Antarctica with the exception of several sites on the leeward side of the ice divides.

  • 3. Iizuka, Yoshinori
    et al.
    Karlin, Torbjorn
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hansson, Margareta
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Sulphate and chloride aerosols during Holocene and last glacial periods preserved in the Talos Dome Ice Core, a peripheral region of Antarctica2013In: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 65, 20197- p.Article in journal (Refereed)
    Abstract [en]

    Antarctic ice cores preserve the record of past aerosols, an important proxy of past atmospheric chemistry. Here we present the aerosol compositions of sulphate and chloride particles in the Talos Dome (TD) ice core from the Holocene and Last Glacial Period. We find that the main salt types of both periods are NaCl, Na2SO4 and CaSO4, indicating that TD ice contains relatively abundant sea salt (NaCl) from marine primary particles. By evaluating the molar ratio of NaCl to Na2SO4, we show that about half of the sea salt does not undergo sulphatisation during late Holocene. Compared to in inland Antarctica, the lower sulphatisation rate at TD is probably due to relatively little contact between sea salt and sulphuric acid. This low contact rate can be related to a reduced time of reaction for marine-sourced aerosol before reaching TD and/or to a reduced post-depositional effect from the higher accumulation rate at TD. Many sulphate and chloride salts are adhered to silicate minerals. The ratio of sulphate-adhered mineral to particle mass and the corresponding ratio of chloride-adhered mineral both increase with increasing dust concentration. Also, the TD ice appears to contain Ca(NO3)(2) or CaCO3 particles, thus differing from aerosol compositions in inland Antarctica, and indicating the proximity of peripheral regions to marine aerosols.

  • 4. Iizuka, Yoshinori
    et al.
    Tsuchimoto, Akira
    Hoshina, Yu
    Sakurai, Toshimitsu
    Hansson, Margareta
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Karlin, Torbjörn
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fujita, Koji
    Nakazawa, Fumio
    Motoyama, Hideaki
    Fujita, Shuji
    The rates of sea salt sulfatization in the atmosphere and surface snow of inland Antarctica2012In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 117, D04308- p.Article in journal (Refereed)
    Abstract [en]

    Most of the aerosol particles present in the surface snow and ice of inland Antarctica come from primary sea salt (sodium chloride) and marine biological activity (methansulfonic and sulfuric acids). Melted water from surface snow, firn, and Holocene ice contains mainly sodium, chloride, and sulfate ions. Although it is well known that sea salt aerosols react rapidly with sulfuric acid, a process known as sulfatization, it is not known when this process takes place. In this research we undertake to measure the proportion of sea salt aerosols that undergo sulfatization in the atmosphere and surface snow, as opposed to deeper ice, in order to understand the suitability of sea salt aerosols as a proxy for past climates in deep ice cores. We directly measure the sulfatization rates in recently fallen snow (0-4 m in depth) collected at the Dome Fuji station, using X-ray dispersion spectroscopy to determine the constituent elements of soluble particles and computing the molar ratios of sodium chloride and sodium sulfate. We estimate that about 90% of the initial sea salt aerosols sulfatize as they are taken up by precipitation over Dome Fuji or in the snowpack within one year after being deposited on the ice sheet.

  • 5.
    Jansson, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Tarfala forskningsstation.
    Linderholm, Hans W.
    Pettersson, Rickard
    Karlin, Torbjörn
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Mörth, Carl-Magnus
    Department of Geology and Geochemistry.
    Assessing the possibility to couple chemical signals in winter snow on Storglaciären to atmospheric climatology2007In: Annals of Glaciology, ISSN 1727-5644, Vol. 46, 335-341 p.Article in journal (Refereed)
  • 6. Wilhelms, Frank
    et al.
    Miller, Heinrich
    Gerasimoff, Michael D.
    Druecker, Cord
    Frenzel, Andreas
    Fritzsche, Diedrich
    Grobe, Hannes
    Hansen, Steffen Bo
    Hilmarsson, Sverrir A. E.
    Hoffmann, Georg
    Hörnby, Kerstin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Jaeschke, Andrea
    Jakobsdottir, Steinunn S.
    Juckschat, Paul
    Karsten, Achim
    Karsten, Lorenz
    Kaufmann, Patrik R.
    Karlin, Torbjorn
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Kohlberg, Eberhard
    Kleffel, Guido
    Lambrecht, Anja
    Lambrecht, Astrid
    Lawer, Gunther
    Schaermeli, Ivan
    Schmitt, Jochen
    Sheldon, Simon G.
    Takata, Morimasa
    Trenke, Marcus
    Twarloh, Birthe
    Valero-Delgado, Fernando
    Wilhelms-Dick, Dorothee
    The EPICA Dronning Maud Land deep drilling operation2014In: Annals of Glaciology, ISSN 0260-3055, E-ISSN 1727-5644, Vol. 55, no 68, 355-366 p.Article in journal (Refereed)
    Abstract [en]

    We report on the EPICA Dronning Maud Land (East Antarctica) deep drilling operation. Starting with the scientific questions that led to the outline of the EPICA project, we introduce the setting of sister drillings at NorthGRIP and EPICA Dome C within the European ice-coring community. The progress of the drilling operation is described within the context of three parallel, deep-drilling operations, the problems that occurred and the solutions we developed. Modified procedures are described, such as the monitoring of penetration rate via cable weight rather than motor torque, and modifications to the system (e.g. closing the openings at the lower end of the outer barrel to reduce the risk of immersing the drill in highly concentrated chip suspension). Parameters of the drilling (e.g. corebreak force, cutter pitch, chips balance, liquid level, core production rate and piece number) are discussed. We also review the operational mode, particularly in the context of achieved core length and piece length, which have to be optimized for drilling efficiency and core quality respectively. We conclude with recommendations addressing the design of the chip-collection openings and strictly limiting the cable-load drop with respect to the load at the start of the run.

  • 7. Wolff, E. W.
    et al.
    Barbante, C.
    Becagli, S.
    Bigler, M.
    Boutron, C. F.
    Castellano, E.
    de Angelis, M.
    Federer, U.
    Fischer, H.
    Fundel, F.
    Hansson, Margareta
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hutterli, M.
    Jonsell, Ulf
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Karlin, Torbjörn
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kaufmann, P.
    Lambert, F.
    Littot, G. C.
    Mulvaney, R.
    Roethlisberger, R.
    Ruth, U.
    Severi, M.
    Siggaard-Andersen, M. L.
    Sime, L. C.
    Steffensen, J. P.
    Stocker, T. F.
    Traversi, R.
    Twarloh, B.
    Udisti, R.
    Wagenbach, D.
    Wegner, A.
    Changes in environment over the last 800,000 years from chemical analysis of the EPICA Dome C ice core2010In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 29, no 1-2, 285-295 p.Article in journal (Refereed)
    Abstract [en]

    The EPICA ice core from Dome C extends 3259 m in depth, and encompasses 800 ka of datable and sequential ice. Numerous chemical species have been measured along the length of the cores. Here we concentrate on interpreting the main low-resolution patterns of major ions. We extend the published record for non-sea-salt calcium, sea-salt sodium and non-sea-salt sulfate flux to 800 ka. The non-sea-salt calcium record confirms that terrestrial dust originating from South America closely mirrored Antarctic climate, both at orbital and millennial timescales. A major cause of the main trends is most likely climate in southern South America, which could be sensitive to subtle changes in atmospheric circulation. Sea-salt sodium also follows temperature, but With a threshold at low temperature. We re-examine the use of sodium as a sea ice proxy, concluding that it is probably reflecting extent, with high salt concentrations reflecting larger ice extents. With this interpretation, the sodium flux record indicates low ice extent operating as an amplifier in warm interglacials. Non-sea-salt sulfate flux is almost constant along the core, confirming the lack of change in marine productivity (for sulfur-producing organisms) in the areas of the Southern Ocean contributing to the flux at Dome C. For the first time we also present long records of reversible species such as nitrate and chloride, and show that the pattern of post-depositional losses described for shallower ice is maintained in older ice. It appears possible to use these concentrations to constrain snow accumulation rates in interglacial ice at this site, and the results suggest a possible correction to accumulation rates in one early interglacial. Taken together the chemistry records offer a number of constraints on the way the Earth system combined to give the major climate fluctuations of the late Quaternary period.

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