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  • 1.
    Beaudon, Emilie
    et al.
    Univ Lapland, Arctic Ctr, Rovaniemi 96101, Finland..
    Arppe, Laura
    Univ Helsinki, Dept Geosci & Geog, FIN-00014 Helsinki, Finland..
    Jonsell, Ulf
    Univ Politecn Madrid, ETSI Telecomun, City Univ, E-28040 Madrid, Spain.;Uppsala Univ, Dept Earth Sci, S-75236 Uppsala, Sweden..
    Martma, Tonu
    Tallinn Univ Technol, Inst Geol, EE-19086 Tallinn, Estonia..
    Moeller, Marco
    Rhein Westfal TH Aachen, Dept Geog, D-52056 Aachen, Germany..
    Pohjola, Veijo A.
    Uppsala Univ, Dept Earth Sci, S-75236 Uppsala, Sweden..
    Scherer, Dieter
    Tech Univ Berlin, Dept Ecol, D-12165 Berlin, Germany..
    Moore, John C.
    Univ Lapland, Arctic Ctr, Rovaniemi 96101, Finland.;Beijing Normal Univ, Coll Global Change, Beijing 100875, Peoples R China.;Beijing Normal Univ, Coll Earth Syst Sci, Beijing 100875, Peoples R China..
    SPATIAL AND TEMPORAL VARIABILITY OF NET ACCUMULATION FROM SHALLOW CORES FROM VESTFONNA ICE CAP (NORDAUSTLANDET, SVALBARD)2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93A, no 4, p. 287-299Article in journal (Refereed)
    Abstract [en]

    We analyse ice cores from Vestfonna ice cap (Nordaustlandet, Svalbard). Oxygen isotopic measurements were made on three firn cores (6.0, 11.0 and 15.5 m deep) from the two highest summits of the glacier located on the SWNE and NWSE central ridges. Sub-annual d18O cycles were preserved and could be counted visually in the uppermost parts of the cores, but deeper layers were affected by post-depositional smoothing. A pronounced d18O minimum was found near the bottom of the three cores. We consider candidates for this d18O signal to be a valuable reference horizon since it is also seen elsewhere in Nordaustlandet. We attribute it to isotopically depleted snow precipitation, which NCEP/NCAR reanalysis shows was unusual for Vestfonna, and came from northerly air during the cold winter of 1994/95. Finding the 1994/95 time marker allows establishment of a precise depth/age scale for the three cores. The derived annual accumulation rates indirectly fill a geographical gap in mass balance measurements and thus provide information on spatial and temporal variability of precipitation over the glacier for the period spanned by the cores (19922009). Comparing records at the two locations also reveals that the snow net accumulation at the easternmost part of Vestfonna was only half of that in the western part over the last 17 years.

  • 2.
    Jonsell, Ulf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Air and Water Science.
    Hansson, Margareta E.
    Siggard-Andresen, Marie-Louise
    Steffensen,, Jörgen-Peder
    Comparison of northern and central Greenland ice core records of methanesulfonate covering the last glacial period2007In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 112, no D14, p. D14313-D14313.11Article in journal (Refereed)
    Abstract [en]

    Methanesulfonate (MS-) is measured in ice cores with the objective to obtain a proxy record of marine phytoplankton production of dimethylsulfide (DMS). We present a continuous MS- record covering the last glacial period from the North Greenland Ice Core Project (NGRIP) ice core and compare this record with the corresponding records previously presented from Greenland and, in particular, with the GISP2 ice core located 320 km south of NGRIP. Despite that the records have similar mean concentrations, their responses to climatic changes during the last glacial period are slightly different. NGRIP MS- concentrations were higher during the cold marine isotopic stages (MIS) 2 and 4 and lower during the warm MIS 5. This long-term trend in MS-, which is similar to the inverse of the corresponding trend in δ 18O, is not detected in the GISP2 MS- record. A systematic response in MS- concentrations to changes between Greenland stadials and interstadials is only detected in the GISP2 record. The different responses of the MS- signals to climate change during the last glacial period are possibly related to the partitioning of air masses reaching the two sites. In contrast to observations from Antarctic records, dust concentrations do not affect the MS- concentrations in the ice, whereas the deposition of sulfate probably is enhanced by high dust concentrations in the atmosphere. The MS- signal has a higher potential of being a proxy record of DMS production changes in Greenlandic compared to Antarctic ice cores.

  • 3.
    Jonsell, Ulf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Air and Water Science.
    Hansson, Margareta
    Mörth, Carl-Magnus
    Correlation between concentrations of acids and oxygen isotope ratios in polar surface snow caused by local redeposition2007In: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 59, no 2, p. 326-335Article in journal (Refereed)
    Abstract [en]

    Investigation of centimeter-scale snow surface chemistry has been carried out at two polar sites with different site characteristics–in Dronning Maud Land, Antarctica and on the Greenland ice sheet, respectively. Large variations in both impurity content and stable oxygen isotope ratios (δ18O) were found on the submeter scale. δ18O and the concentration of nitrate correlated at both sites (r = 0.81 and 0.82, respectively). At the Antarctic site, δ18O is also correlated to concentrations of methanesulphonate (r = 0.84) and sulphate (r = 0.83) while no such correlation exists at the Greenland site. Instead, a strong anticorrelation (r = –0.85) between sulphate and methanesulphonate is found among the samples from the Greenland site. The ions correlating with δ18O at the two sites were probably deposited as acids. Our tentative explanation is that local redeposition of water vapour enriching the snow surface with the lighter isotopes is associated with simultaneous enhanced scavenging of the acids. The responsible process thereby significantly alters the chemical signals of the snow surface.

  • 4.
    Moeller, Marco
    et al.
    Rhein Westfal TH Aachen, Dept Geog, D-52062 Aachen, Germany..
    Finkelnburg, Roman
    Tech Univ Berlin, Dept Ecol, D-12165 Berlin, Germany..
    Braun, Matthias
    Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA.;Univ Bonn, Ctr Remote Sensing Land Surfaces, D-5300 Bonn, Germany..
    Hock, Regine
    Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA.;Uppsala Univ, Dept Earth Sci, SE-75236 Uppsala, Sweden..
    Jonsell, Ulf
    Uppsala Univ, Dept Earth Sci, SE-75236 Uppsala, Sweden.;Univ Politecn Madrid, Escuela Tecn Super Ingenieros Telecomunicac, Madrid, Spain..
    Pohjola, Veijo A.
    Uppsala Univ, Dept Earth Sci, SE-75236 Uppsala, Sweden..
    Scherer, Dieter
    Tech Univ Berlin, Dept Ecol, D-12165 Berlin, Germany..
    Schneider, Christoph
    Rhein Westfal TH Aachen, Dept Geog, D-52062 Aachen, Germany..
    Climatic mass balance of the ice cap Vestfonna, Svalbard: A spatially distributed assessment using ERA-Interim and MODIS data2011In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 116, article id F03009Article in journal (Refereed)
    Abstract [en]

    The ice cap Vestfonna in the northern Svalbard archipelago is one of the largest ice bodies of the European Arctic (similar to 2400 km(2)), but little is known about its mass balance. We model the climatic mass balance of the ice cap for the period September 2000 to August 2009 on a daily basis. Ablation is calculated by a spatially distributed temperature-radiation-index melt model. Air temperature forcing is provided by ERA-Interim data that is downscaled using data from an automatic weather station operated on the ice cap. Spatially distributed net shortwave radiation fluxes are obtained from standard trigonometric techniques combined with Moderate Resolution Imaging Spectroradiometer-based cloud cover and surface albedo information. Accumulation is derived from ERA-Interim precipitation data that are bias corrected and spatially distributed as a function of elevation. Refreezing is incorporated using the P(max) approach. Results indicate that mass balance years are characterized by short ablation seasons (June to August) and correspondingly longer accumulation periods (September to May). The modeled, annual climatic mass balance rate shows an almost balanced mean of -0.02 +/- 0.20 m w.e. yr(-1) (meters water equivalent per year) with an associated equilibrium line altitude of 383 +/- 54 m above sea level (mean +/- one standard deviation). The mean winter balance is +0.32 +/- 0.06 m w.e. yr(-1), and the mean summer balance -0.35 +/- 0.17 m w.e. yr(-1). Roughly one fourth of total surface ablation is retained by refreezing indicating that refreezing is an important component of the mass budget of Vestfonna.

  • 5. Moeller, Marco
    et al.
    Moeller, Rebecca
    Beaudon, Emilie
    Mattila, Olli-Pekka
    Finkelnburg, Roman
    Braun, Matthias
    Grabiec, Mariusz
    Jonsell, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Luks, Bartlomiej
    Puczko, Dariusz
    Scherer, Dieter
    Schneider, Christoph
    Snowpack Characteristics of Vestfonna and De Geerfonna (Nordaustlandet, Svalbard): A Spatiotemporal Analysis Based on Multiyear Snow-Pit Data2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93A, no 4, p. 273-285Article in journal (Refereed)
    Abstract [en]

    Extensive glaciological field measurements were carried out on the ice cap Vestfonna as well as on the minor ice body De Geerfonna (Nordaustlandet, Svalbard) within the framework of IPY Kinnvika. Field campaigns were conducted during the period 20072010 in spring (April/May) and summer (August). In this study we compile and present snow cover information obtained from 22 snow pits that were dug on Vestfonna during this period. Locations are along two transects on the northwestern, land terminating slope of the ice cap, on its central summit, Ahlmann Summit, and at a set of several other locations in the eastern and northern part of the ice cap. Snow-cover information acquired from four snow pits on adjacent De Geerfonna is also incorporated in this study. Field data are analysed regarding snow stratigraphy, snow density, snow hardness and snow temperature. Results reveal mean snow densities of around 400 kg m-3 for the snowpack of Vestfonna with no apparent spatial or interannual variability. A distinctly higher value of more than 450 kg m-3 was obtained for De Geerfonna. A spatial comparison of snow water equivalents above the previous end-of-summer surface serves for obtaining insights into the spatial distribution of snow accumulation across Vestfonna. Altitude was found to be the only significant spatial parameter for controlling snow accumulation across the ice cap.

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