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  • 1.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Flarks in the Maloti, Lesotho1989In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 71, p. 105-111Article in journal (Refereed)
    Abstract [en]

    Flarks are reported to occur in mires in Qathlamba (the Drakensberg Range) of the Maloti, Lesotho at an altitude of 3200 m a.s.l. Flarks are not previously reported from Africa. Conditions for the formation and maintenance of flarks are discussed. It is argued that local waterlogging is a more likely explanation for the formation of flarks in Qathlamba than frost action.

  • 2.
    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.

  • 3.
    Beaudon, Emilie
    et al.
    Lapplands Universitetet, Finland.
    Arppe, Laura
    Jonsell, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Martma, Tonu
    Möller, Marco
    Pohjola, Veijo A
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Scherer, Dieter
    Moore, John
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    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. 93, 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 SW–NE and NW–SE central ridges. Sub-annual δ18O 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 δ18O minimum was found near the bottom of the three cores. We consider candidates for this δ18O 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 (1992–2009). 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.

  • 4.
    Berglund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    THE HIGHEST POSTGLACIAL SHORE LEVELS AND GLACIO-ISOSTATIC UPLIFT PATTERN IN NORTHERN SWEDEN2012In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 94A, no 3, p. 321-337Article in journal (Refereed)
    Abstract [en]

    The detailed clay varve chronology and an extensive knowledge of the highest postglacial shore level elevation (HS) in northern Sweden, along the Bothnian western coast, provides opportunities for determining the pattern of isostatic rise and centre of uplift from the early Holocene. The shore level of c. 10 100 cal yr bp (10 ka) for this area is determined by subtracting, from the metachronous HS elevations, the fall in relative sea level between local deglaciation time and the chosen reference time. The area of highest uplift since 10 ka is situated somewhat north of the location with the world-record HS (Skuleberget in Angermanland), but south of the area with most rapid current rise. Wave erosion marks in the studied area are seen to be more consistent indicators of HS than glaciofluvial delta levels. The gradients of shore marks at 10 ka are generally small within the investigation area. The regional 10 ka shore level pattern shows considerable irregularity compared to the current uplift. Central Sweden and western Finland show 10 ka gradients that indicate isostatic response to late (1310 ka bp) glacial unloading. Indications of a secondary uplift centre west of the present investigation area are reported in previous work; this also suggests rapid isostatic response to unloading. Finally, the possibility of identifying errors in the varve-dated deglaciation chronology via the 10 ka shore level pattern is illustrated.

  • 5.
    Berglund, Mikael
    Dalarna University, School of Education, Health and Social Studies, Geography.
    The highest postglacial shore levels and glacio-isostatic uplift pattern in northern Sweden2012In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 94, no 3, p. 321-337Article in journal (Refereed)
    Abstract [en]

    The detailed clay varve chronology and an extensive knowledge of the highest postglacial shore level elevation (HS) in northern Sweden, along the Bothnian western coast, provides opportunities for determining the pattern of isostatic rise and centre of uplift from the early Holocene. The shore level of c. 10 100 cal yr bp (10 ka) for this area is determined by subtracting, from the metachronous HS elevations, the fall in relative sea level between local deglaciation time and the chosen reference time. The area of highest uplift since 10 ka is situated somewhat north of the location with the world-record HS (Skuleberget in Angermanland), but south of the area with most rapid current rise. Wave erosion marks in the studied area are seen to be more consistent indicators of HS than glaciofluvial delta levels. The gradients of shore marks at 10 ka are generally small within the investigation area. The regional 10 ka shore level pattern shows considerable irregularity compared to the current uplift. Central Sweden and western Finland show 10 ka gradients that indicate isostatic response to late (1310 ka bp) glacial unloading. Indications of a secondary uplift centre west of the present investigation area are reported in previous work; this also suggests rapid isostatic response to unloading. Finally, the possibility of identifying errors in the varve-dated deglaciation chronology via the 10 ka shore level pattern is illustrated.

  • 6. Beylich, A A
    et al.
    Gintz, D
    Effects of high-magnitude/low-frequency fluvial events generated by intense snowmelt or heavy rainfall in arctic periglacial environments in northern Swedish Lapland and northern Siberia2004In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 86A, no 1, p. 11-29Article in journal (Refereed)
    Abstract [en]

    In the Latnjavagge drainage basin (68degrees21’N, 18degrees29’E), an arctic-oceanic periglacial environment in northernmost Swedish Lapland, the fluvial sediment transport and the characteristics and importance of high-magnitude/low-frequency fluvial events generated by intense snowmelt or heavy rainfall have been investigated and compared with snowmelt- and rainfall-induced discharge peaks in the Levinson-Lessing Lake basin (Krasnaya river system) on the Taimyr Peninsula, an arctic periglacial environment in northern Siberia (74degrees32’N, 98degrees35’E). In Latnjavagge (9 km(2)) the intensity of fluvial sediment transport is very low. Most of the total annual sediment load is transported in a few days during snowmelt generated runoff peaks. Due to the continuous and very stable vegetation covering most areas below 1300 m a.s.l. in the Latnjavagge catchment, larger rainfall events are of limited importance for sediment transport in this environment. Compared to that, in the c. 40 times larger Krasnaya river system rainfall-generated runoff peaks cause significant sediment transport. The main sediment sources in the Latnjavagge drainage basin are permanent ice patches, channel debris pavements mobilized during peak discharges and exposing fines, and material mobilized by slush-flows. In the Krasnaya river system river bank erosion is the main sediment source. In both periglacial environments more than 90% of the annual sediment yield is transported during runoff peaks. The results from both arctic periglacial environments underline the high importance of high-magnitude/low-frequency fluvial events for the total fluvial sediment budgets of periglacial fluvial systems. Restricted sediment availability is in both arctic environments the major controlling factor for this behaviour.

  • 7. Beylich, A A
    et al.
    Sandberg, O
    Geomorphic effects of the extreme rainfall event of 20-21 July, 2004 in the Latnjavagge catchment, northern Swedish Lapland2005In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 87A, no 3, p. 409-419Article in journal (Refereed)
    Abstract [en]

    Mass transfers triggered by a rare rainfall event on 20-21 July, 2004, with 58.4 mm of rain within 24 h and 71.7 mm of rain within 48 It in the Latnjavagge catchment (9 km(2), 950-1440 m a.s.l.; 68 degrees 20 ‘ N 18 degrees 30 ‘ E) in the higher Abisko mountain region (Swedish Lapland), are quantified and analysed in direct comparison with mean annual mass transfers in this drainage basin. In years without rare rainfall events the Latnjavagge catchment is characterized by restricted sediment availability resulting in low mechanical denudation and mass transfers. During the rare rainfall event of 20-21 July, 2004, major stability thresholds on the slope systems (triggering debris flows and slides) and in the channel systems (break-up of channel debris pavements and step-pool systems) in the Latnjavagge catchment were passed and mass transfers by debris flows, slides and fluvial debris transport in creeks and channels were several times higher than the mean annual mass transfers in Latnjavagge. In the calculation of longer-term mass transfers and sediment budgets, rare events like the 20-21 July, 2004 rainfall event have to be considered as essential components. A reliable estimation of the recurrence intervals of such rare events is especially problematic. The general problem of defining an adequate length of process monitoring programmes is pointed out.

  • 8.
    Boelhouwers, Jan
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Jonsson, Mikael
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Critical assessment of the 2°C min−1 threshold for thermal stress weathering2013In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 95, no 4, p. 285-293Article in journal (Refereed)
    Abstract [en]

    Rock surface temperature changes in excess of 2°C min−1 have been argued to result in permanent strain in rock. The single threshold value and the supposed importance of a rate of 2°C min−1 rock temperature change is rejected, based on lack of a sufficient empirical basis, contrasting results from acoustic emission studies, varying strength properties of different rock types, lack of data on actual strain resulting from short-term temperature variations, and lack of notable long-term weathering effects in Nordic environments. Based on the presented discussion, the role of thermal shock weathering in cold regions is questioned and renewed emphasis is placed on the importance of absolute temperature and measurement of strain, as well as spatial temperature gradients.

  • 9.
    Boin, Arjen
    et al.
    Department of Political Science, Leiden University, Leiden, The Netherlands.
    Bynander, Fredrik
    Swedish Defence University, Department of Security, Strategy and Leadership (ISSL), CRISMART (National Center for Crisis Management Research and Training).
    Explaining Success and Failure in Crisis Coordination2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 123-135Article in journal (Refereed)
    Abstract [en]

    In virtually every assessment of responses to large-scale crises and disasters, coordination is identified as a critical failure factor. After the crisis, official committees and political opponents often characterize the early phases of the response as a ‘failure to coordinate.’ Not surprisingly, improved coordination quickly emerges as the prescribed solution. Coordination, then, is apparently both the problem and the solution. But the proposed solutions rarely solve the problem: coordination continues to mar most crises and disasters. In the absence of a shared body of knowledge on coordination, it is hard to formulate a normative framework that allows for systematic assessment of coordination in times of crisis. As coordination is widely perceived as an important function of crisis and disaster management, this absence undermines a fair and balanced assessment of crisis management performance. This paper seeks to address that void. We aim to develop a framework that explains both the failure and success of crisis coordination. We do this by exploring the relevant literature, reformulating what coordination is and distilling from research the factors that cause failure and success.

  • 10.
    Brandt, Maja
    SMHI, Core Services.
    GENERATION, TRANSPORT AND DEPOSITION OF SUSPENDED AND DISSOLVED MATERIAL - EXAMPLES FROM SWEDISH RIVERS1990In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 72, no 3-4, p. 273-283Article in journal (Refereed)
    Abstract [en]

    Soil erosion, sediment transport and deposition in river systems in Sweden are discussed. The database consists of observations from a research project and from the Swedish network for the measurement of sediment transport. Examples are given from measurements in small plots, and from river basins of different sizes and characteristics. Effects of hydrological regime, of deposition in lakes, and of geology and human impact are illustrated. It was found that observations of erosion losses in index plots cannot easily be extrapolated to large areas, and that trends of transport most likely reflect trends in runoff.

  • 11.
    Braun, Matthias
    et al.
    Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA.;Univ Bonn, Ctr Remote Sensing Land Surfaces, D-53113 Bonn, Germany..
    Pohjola, Veijo A.
    Uppsala Univ, Dept Earth Sci Air Water & Landscape Sci, SE-75236 Uppsala, Sweden..
    Pettersson, Rickard
    Uppsala Univ, Dept Earth Sci Air Water & Landscape Sci, SE-75236 Uppsala, Sweden..
    Moeller, Marco
    Rhein Westfal TH Aachen, Dept Geog, D-52056 Aachen, Germany..
    Finkelnburg, Roman
    Tech Univ Berlin, Dept Ecol, D-12165 Berlin, Germany..
    Falk, Ulrike
    Univ Bonn, Ctr Remote Sensing Land Surfaces, D-53113 Bonn, Germany..
    Scherer, Dieter
    Tech Univ Berlin, Dept Ecol, D-12165 Berlin, Germany..
    Schneider, Christoph
    Rhein Westfal TH Aachen, Dept Geog, D-52056 Aachen, Germany..
    CHANGES OF GLACIER FRONTAL POSITIONS OF VESTFONNA (NORDAUSTLANDET, SVALBARD)2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93A, no 4, p. 301-310Article in journal (Refereed)
    Abstract [en]

    Glaciers in Svalbard have shown considerable mass loss in recent years with a reported acceleration in the western and southern parts of the archipelago. However, for the ice cap Vestfonna, in northeastern Svalbard, climatic mass balance modelling has suggested almost balanced conditions over a period of nine years (20002009). A slightly positive geodetic mass balance (19902005) has been reported from a comparison of laser altimetry to older DEMs. A heterogeneous situation has been depicted for the various catchments, and hence changes in glacier extent can reveal additional information of glacier status, in particular when dealing with surge-type glaciers. We analysed a 34-year data record of multi-spectral satellite imagery in order to study changes in glacier frontal positions of the ice cap Vestfonna. A consistent pattern of almost steady retreat of the southern and north-eastern outlet glaciers of the ice cap is observed while Franklinbreen, the only major outlet glacier draining towards the north-west shows re-advance. This is consistent with an observed speed up and potential upcoming surge of this outlet. The glacier retreat on the southern coast also agrees with ICESat elevation change measurements. However, due to the glacier response time no direct relations between frontal retreat and surface mass balance can be drawn from the short observation period. The heterogeneous pattern of changes with on-going dynamic adjustments in some areas make the ice cap Vestfonna an ideal test site for future monitoring activities including novel techniques like differential interferometry from bi-static SAR systems.

  • 12.
    Braun, Matthias
    et al.
    University of Alaska.
    Pohjola, Veijo A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Pettersson, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Möller, Marco
    Finkelnburg, Roman
    Falk, Ulrike
    Scherer, Dieter
    Schneider, Christoph
    Changes of glacial front positions of Vestfonna (Nordaustlandet, Svalbard)2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93, no 4, p. 301-310Article in journal (Refereed)
    Abstract [en]

    Glaciers in Svalbard have shown considerable mass loss in recent years with a reported acceleration in the western and southern parts of the archipelago. However, for the ice cap Vestfonna, in northeastern Svalbard, climatic mass balance modelling has suggested almost balanced conditions over a period of nine years (2000–2009). A slightly positive geodetic mass balance (1990–2005) has been reported from a comparison of laser altimetry to older DEMs. A heterogeneous situation has been depicted for the various catchments, and hence changes in glacier extent can reveal additional information of glacier status, in particular when dealing with surge-type glaciers. We analysed a 34-year data record of multi-spectral satellite imagery in order to study changes in glacier frontal positions of the ice cap Vestfonna. A consistent pattern of almost steady retreat of the southern and north-eastern outlet glaciers of the ice cap is observed while Franklinbreen, the only major outlet glacier draining towards the north-west shows re-advance. This is consistent with an observed speed up and potential upcoming surge of this outlet. The glacier retreat on the southern coast also agrees with ICESat elevation change measurements. However, due to the glacier response time no direct relations between frontal retreat and surface mass balance can be drawn from the short observation period. The heterogeneous pattern of changes with on-going dynamic adjustments in some areas make the ice cap Vestfonna an ideal test site for future monitoring activities including novel techniques like differential interferometry from bi-static SAR systems.

  • 13.
    Charpentier Ljungqvist, Fredrik
    Stockholm University, Faculty of Humanities, Department of History. Stockholm University, Faculty of Humanities, Centre for Medieval Studies.
    A new reconstruction of temperature variability in the extra-tropical Northern Hemisphere during the last two millennia2010In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 92A, no 3, p. 339-351Article in journal (Refereed)
    Abstract [en]

    A new temperature reconstruction with decadal resolution, covering the last two millennia, is presented for the extra-tropical Northern Hemisphere (90–30°N), utilizing many palaeotemperature proxy records never previously included in any large-scale temperature reconstruction. The amplitude of the reconstructed temperature variability on centennial time-scales exceeds 0.6°C. This reconstruction is the first to show a distinct Roman Warm Period c. AD 1–300, reaching up to the 1961–1990 mean temperature level, followed by the Dark Age Cold Period c. AD 300–800. The Medieval Warm Period is seen c. AD 800–1300 and the Little Ice Age is clearly visible c. AD 1300–1900, followed by a rapid temperature increase in the twentieth century. The highest average temperatures in the reconstruction are encountered in the mid to late tenth century and the lowest in the late seventeenth century. Decadal mean temperatures seem to have reached or exceeded the 1961–1990 mean temperature level during substantial parts of the Roman Warm Period and the Medieval Warm Period. The temperature of the last two decades, however, is possibly higher than during any previous time in the past two millennia, although this is only seen in the instrumental temperature data and not in the multi-proxy reconstruction itself. Our temperature reconstruction agrees well with the reconstructions by Moberg et al. (2005) and Mann et al. (2008) with regard to the amplitude of the variability as well as the timing of warm and cold periods, except for the period c. AD 300–800, despite significant differences in both data coverage and methodology.

  • 14. Chen, D.
    et al.
    Gong, Lebing
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Air and Water Science.
    Xu, Chong-yu
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Air and Water Science.
    Halldin, Sven
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Air and Water Science.
    A high-resolution, gridded dataset for monthly temperature normals (1971 – 2000) in Sweden2007In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 89, no 4, p. 249-261Article in journal (Refereed)
    Abstract [en]

    A baseline climatology is required in evaluating climate variability and changes on regional and local scales. Gridded climate normals, i.e. averages over a 30-year period, are of special interest since they can be readily used for validation of climate models. This study is aimed at creating an updated gridded dataset for Swedish monthly temperature normals over the period 1971–2000, based on standard 2-m air temperature records at 510 stations in mainland Sweden. Spatial trends of the normal temperatures were modelled as functions of latitude, longitude and elevation by multiple linear regression. The study shows that the temperature normals are strongly correlated with latitude throughout the year and especially in cold months, while elevation was a more important factor in June and July. Longitude played a minor role and was only significant in April and May. Regression equations linking temperature to latitude, longitude and elevation were set up for each month. Monthly temperature normals were detrended by subtracting spatial trends given by the regressions. Ordinary kriging was then applied to both original data (simple method) and de-trended data (composite method) to model the spatial variability and to perform spatial gridding. The multiple regressions showed that between 82% (summer) and 96% (winter) of the variance in monthly temperature normals could be explained by latitude and elevation. Unexplained variances, i.e. the residuals, were modelled with ordinary kriging with exponential semivariograms. The composite grid estimates were calculated by adding the multiple linear trends back to the interpolated residuals at each grid point. Kriged original temperature normals provided a performance benchmark. The cross–validation shows that the interpolation errors of the normals are significantly reduced if the composite method rather than the simple one was used. A gridded monthly dataset with 30-arcsecond spacing was created using the established trends, the kriging model and a digital topographic dataset.

  • 15. Englund, David
    et al.
    Brunberg, Anna
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    A CASE STUDY OF A FRESHWATER PEARL MUSSEL (MARGARITIFERA MARGARITIFERA) POPULATION IN CENTRAL SWEDEN2008In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 90A, no 4, p. 251-258Article in journal (Refereed)
    Abstract [en]

    Most of the Margaritifera margaritifera populations in Sweden are not reproducing. Land use such as forestry, eutrophication and water regulation for hydropower are commonly reported causes for the absence of reproduction. A brook with a very dense population of pearl mussels has been investigated with regard to the age distribution of the population and their habitat, in order to discover the reason for the absence of reproduction. The population consisted almost entirely of old mussels with very few young ones. The water flow and chemistry of the water are very stable and well buffered, due to a large glacifluvial deposit in the catchment area. The substrate in the stream is favourable and well aerated to a depth of at least 15 cm. Forestry has been practised with care for at least the last 15 years to avoid siltation of the stream sediments. The most likely reason for the lack of reproduction seems to be the water regulation of the main stream introduced 60 years ago, which has left the main stream dry seasonally. This is likely to have affected the population of brown trout which is the host for the first life-stage of the mussels, the glochidia.

  • 16.
    Englund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Brunberg, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Jacks, Gunnar
    A Case Study of a Freshwater Pearl Mussel (Margaritifera margaritifera) Population in Central Sweden2008In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 90A, no 4, p. 251-258Article in journal (Refereed)
    Abstract [en]

    Most of the Margaritifera margaritifera populations in Sweden are not reproducing. Land use such as forestry, eutrophication and water regulation for hydropower are commonly reported causes for the absence of reproduction. A brook with a very dense population of pearl mussels has been investigated with regard to the age distribution of the population and their habitat, in order to discover the reason for the absence of reproduction. The population consisted almost entirely of old mussels with very few young ones. The water flow and chemistry of the water are very stable and well buffered, due to a large glacifluvial deposit in the catchment area. The substrate in the stream is favourable and well aerated to a depth of at least 15 cm. Forestry has been practised with care for at least the last 15 years to avoid siltation of the stream sediments. The most likely reason for the lack of reproduction seems to be the water regulation of the main stream introduced 60 years ago, which has left the main stream dry seasonally. This is likely to have affected the population of brown trout which is the host for the first life-stage of the mussels, the glochidia.

  • 17.
    Garcia-Urquia, Elias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics. National Autonomous University of Honduras.
    Axelsson, Kennet
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Rainfall thresholds for the occurrence of urban landslides in Tegucigalpa, Honduras: An application of the critical rainfall intensity2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 61-83Article in journal (Refereed)
  • 18.
    Girons Lopez, Marc
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Wennerström, Hjalmar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Nordén, Lars-Åke
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Location and Density of Rain Gauges for the Estimation of Spatial Varying Precipitation2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 167-179Article in journal (Refereed)
    Abstract [en]

    Accurate estimation of precipitation and its spatial variability is crucial for reliable discharge simulations. Although radar and satellite based techniques are becoming increasingly widespread, quantitative precipitation estimates based on point rain gauge measurement interpolation are, and will continue to be in the foreseeable future, widely used. However, the ability to infer spatially distributed data from point measurements is strongly dependent on the number, location and reliability of measurement stations.

    In this study we quantitatively investigated the effect of rain gauge network configurations on the spatial interpolation by using the operational hydrometeorological sensor network in the Thur river basin in north-eastern Switzerland as a test case. Spatial precipitation based on a combination of radar and rain gauge data provided by MeteoSwiss was assumed to represent the true precipitation values against which the precipitation interpolation from the sensor network was evaluated. The performance using scenarios with both increased and decreased station density were explored. The catchment-average interpolation error indices significantly improve up to a density of 24 rain gauges per 1000 km2, beyond which improvements were negligible. However, a reduced rain gauge density in the higher parts of the catchment resulted in a noticeable decline of the performance indices. An evaluation based on precipitation intensity thresholds indicated a decreasing performance for higher precipitation intensities. The results of this study emphasise the benefits of dense and adequately distributed rain gauge networks.

  • 19.
    Guinea Barrientos, Hector E.
    et al.
    Uppsala Univ, Dept Earth Sci, S-75236 Uppsala, Sweden.;Univ San Carlos, Facultad Agron, Guatemala City, Guatemala..
    Swain, Ashok
    Uppsala Univ, Ctr Sustainable Dev, S-75236 Uppsala, Sweden..
    Wallin, Marcus B.
    Uppsala Univ, Dept Ecol & Genet Limnol, S-75236 Uppsala, Sweden..
    Nyberg, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Centre for Climate and Safety. Karlstad Univ, Ctr Climate & Safety, Karlstad, Sweden..
    Disaster management cooperation in central america: The case of rainfall-induced natural disasters2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 85-96Article in journal (Refereed)
    Abstract [en]

    Rainfall-induced natural disasters rank first among all natural disasters in Central America. Due to the geographical conditions of the Central American region, it is common that two or more countries are struck by the same rainfall event, for example Hurricane Mitch in 1998 affected the entire Central American region, killing more than 18000 people. As a consequence, Central American countries have started to promote regional policies and programs that aim for better preparation and response to these events, including disaster management cooperation. However, cooperation poses several challenges that may hinder its goals. In order to analyse these challenges, we present analysis in this paper of the current policy and legal institutions as well as the main challenges that may hinder international disaster management cooperation in Central America.

  • 20.
    Guinea Barrientos, Héctor Estuardo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Swain, Ashok
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Uppsala Centre for Sustainable Development, CSD Uppsala.
    Wallin, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Nyberg, Lars
    Disaster Management Cooperation in Central America: The Case of Rainfall-induced Natural Disasters2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 85-96Article in journal (Refereed)
    Abstract [en]

    Rainfall-induced natural disasters rank first among all natural disasters in Central America. Due to the geographical conditions of the Central American region, it is common that two or more countries are struck by the same rainfall event, for example Hurricane Mitch in 1998 affected the entire Central American region, killing more than 18 000 people. As a consequence, Central American countries have started to promote regional policies and programs that aim for better preparation and response to these events, including disaster management cooperation. However, cooperation poses several challenges that may hinder its goals. In order to analyse these challenges, we present analysis in this paper of the current policy and legal institutions as well as the main challenges that may hinder international disaster management cooperation in Central America.

  • 21.
    Hall, Adrian
    et al.
    University of St Andrews, Scotland, UK.
    Ebert, Karin
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Pre-glacial landform inheritance in a glaciated shield landscape2013In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 95, no 1, p. 33-49Article in journal (Refereed)
    Abstract [en]

    We seek to quantify glacial erosion in a low relief shield landscape in northern Sweden. We use GIS analyses of digital elevation models and field mapping of glacial erosion indicators to explore the geomorphology of three granite areas with the same sets of landforms and of similar relative relief, but with different degrees of glacial streamlining. Area 1, the Parkajoki district, shows no streamlining and so is a type area for negligible glacial erosion. Parkajoki retains many delicate pre-glacial features, including tors and saprolites with exposure histories of over 1 Myr. Area 2 shows the onset of significant glacial erosion, with the development of glacially streamlined bedrock hills. Area 3 shows extensive glacial streamlining and the development of hill forms such as large crag and tails and roches moutonnées.

    Preservation of old landforms is almost complete in Area 1, due to repeated covers of cold-based, non-erosive ice. In Area 2, streamlined hills appear but sheet joint patterns indicate that the lateral erosion of granite domes needed to form flanking cliffs and to give a streamlined appearance is only of the order of a few tens of metres. The inheritance of large-scale, pre-glacial landforms, notably structurally controlled bedrock hills and low relief palaeosurfaces, remains evident even in Area 3, the zone of maximum glacial erosion. Glacial erosion here has been concentrated in valleys, leading to the dissection and loss of area of palaeosurfaces. Semi-quantitative estimates of glacial erosion on inselbergs and palaeosurfaces and in valleys provide mean totals for glacial erosion of 8 ± 8 m in Area 1 and 27 ± 11 m in Area 3. These estimates support previous views that glacial erosion depths and rates on shields can be low and that pre-glacial landforms can survive long periods of glaciation, including episodes of wet-based flow.

  • 22.
    Halldin, Sven
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Bynander, Fredrik
    van Groningen, Ernst
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, International Science Programme (ISP).
    Preface: Natural Disaster Science: A Nordic Approach to Integrated Research on Disaster Risk2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 1-7Article in journal (Other academic)
  • 23.
    Halldin, Sven
    et al.
    Uppsala Univ, Dept Earth Sci, SE-75263 Uppsala, Sweden.
    Bynander, Fredrik
    Swedish Defence University, Department of Security, Strategy and Leadership (ISSL), CRISMART (National Center for Crisis Management Research and Training).
    van Groningen, Ernst
    Uppsala Univ, ISP, SE-75121 Uppsala, Sweden.
    Preface: Natural disaster science: a Nordic approach to integrated research on disaster risk2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 1-7Article in journal (Other academic)
  • 24.
    Haussmann, Natalie
    et al.
    Department of Conservation Ecology and Entomology, Stellenbosch University, South Africa.
    Boelhouwers, Jan
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    McGeoch, Melodie
    DST-NRF Centre for Invasion Biology and Cape Research Centre, South African National Parks, Steenberg, South Africa.
    Fine scale variability in soil frost dynamics surrounding cushions of the dominant vascular plant species (Azorella selago) on sub-Antarctic Marion island2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91, no 4, p. 257-268Article in journal (Refereed)
    Abstract [en]

    Through changing soil thermal regimes, soil moisture and affecting weathering and erosion processes plants can have an important effect on the physical properties and structure of soils. Such physical soil changes can in turn lead to biological facilitation, such as vegetation-banked terrace formation or differential seedling establishment. We studied the fine scale variability in soil temperature and moisture parameters, specifically focusing on frost cycle characteristics around cushions of the dominant, vascular plant species, Azorella selago, on sub-Antarctic Marion Island. The frost season was characterised by numerous low intensity and very shallow frost cycles. Soils on eastern cushion sides were found to have lower mean and maximum temperatures in winterthan soils on western cushion sides. In addition, lower variability in temperature was found on eastern cushion sides in winterthan on western cushion sides, probably as a result of higher wind speeds on western cushion sides and/or eastern, lee-side snow accumulation. Despite the mild frost climate, extensive frost heave occurred in the study area, indicating that needle ice forms at temperatures above −2°C. Our results demonstrate the effectiveness of frost pull as a heave mechanism under shallow frost conditions. The results highlight the importance of Azorella cushions in modifying site microclimates and of understanding the consequences of these modifications, such as potentially providing microhabitats. Such potential microhabitats are particularly important in light of current climate change trends on the island, as continued warming and drying will undoubtedly increase the need for thermal and moisture refugia.

  • 25.
    Hormes, Anne
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Beer, Jürg
    Schluechter, Christian
    A geochronological approach to understanding the role of solar activity on Holocene glacier length variability in the Swiss Alps2006In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 88 A, no 4, p. 281-294Article in journal (Refereed)
    Abstract [en]

    We present a radiocarbon data set of 71 samples of wood and peat material that melted out or sheared out from underneath eight presentday mid-latitude glaciers in the Central Swiss Alps. Results indicated that in the past several glaciers have been repeatedly less extensive than they were in the 1990s. The periods when glaciers had a smaller volume and shorter length persisted between 320 and 2500 years. This data set provides greater insight into glacier variability than previously possible, especially for the early and middle Holocene. The radiocarbon-dated periods defined with less extensive glaciers coincide with periods of reduced radio-production, pointing to a connection between solar activity and glacier melting processes. Measured long-term series of glacier length variations show significant correlation with the total solar irradiance. Incoming solar irradiance and changing albedo can account for a direct forcing of the glacier mass balances. Long-term investigations of atmospheric processes that are in interaction with changing solar activity are needed in order to understand the feedback mechanisms with glacier mass balances.

  • 26. Isaksson, E
    et al.
    Divine, D
    Kohler, J
    Martma, T
    Pohjola, V
    Motoyama, H
    Watanabe, O
    Climate oscillations as recorded in Svalbard ice core delta O-18 records between AD 1200 and 19972005In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 87A, no 1, p. 203-214Article in journal (Refereed)
    Abstract [en]

    We apply two different time series analytical tools to 8180 records from two Svalbard ice cores. One ice core is from Lomonosovfonna at 1250 m a.s.l. and the other from Austfonna at 750 m a.s.l. These cores are estimated to cover at least the past 800 years and have been dated using a combination of known reference horizons and glacial modelling. Wavelet analysis reveals low frequency oscillations on the 60-120-year scale on the lower elevation site Austfonna while the higher altitude site on Lomonosovfonna does not reveal such variability throughout the record. The second method, Significant Zero Crossing of Derivates (SiZer) does not resolve the low-frequency periodicity seen in the wavelet analysis. The low-frequency variability resolved by the wavelet analysis is similar to what has been found in various climate records including instrumental temperatures and tree-rings, and has been proposed as the most important oscillation for the observed trends in Arctic air temperatures.

  • 27. Isaksson, Elisabeth
    et al.
    Divine, Dmitry
    Kohler, Jack
    Martma, Tonu
    Pohjola, Veijo
    miljö- och landskapsdynamik. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Environment and Landscape Dynamics. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Motoyama, Hideaki
    Watanabe, Okitsugu
    Climate oscillations as recorded in Svalbard ice core δ 18O records between 1200-1997 AD2005In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 87a, no 1, p. 203-214Article in journal (Refereed)
    Abstract [en]

    We apply two different time series analytical tools to omega18O records from two Svalbard ice cores. One ice core is from Lomonosovfonna at 1250 ma.s.l. and the other from Austfonna at 750 m a.s.l. These cores are estimated to cover at least the past 800 years and have been dated using a combination of known reference horizons and glacial modelling. Wavelet analysis reveals low frequency oscillations on the 60-120-year scale on the lower elevation site Austfonna while the higher altitude site on Lomonosovfonna does not reveal such variability throughout the record. The second method, Significant Zero Crossing of Derivates (SiZer) does not resolve the low-frequency periodicity seen in the wavelet analysis. The low-frequency variability resolved by the wavelet analysis is similar to what has been found in various climate records including instrumental temperatures and tree-rings, and has been proposed as the most important oscillation for the observed trends in Arctic air temperatures.

  • 28. Johansson, Jenny
    et al.
    Hellqvist, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Traustadottir, Ragnheidur
    Fornleifafræðingur Antikva ehf., Garðabæ, Iceland.
    Almgren, Elisabeth
    Environment and climate change during the late Holocene in Hjaltadalur, Skagafjörður, north Iceland, interpreted from peat core analyses and pollen identification2017In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459Article in journal (Refereed)
    Abstract [en]

    We present an overview of the landscape and environmental development of the valley of Hjaltadalur, Skagafjörður in northern Iceland, with the aim to develop more knowledge before and during the settlement of humans in the 9th century, through a combination of several proxies such as pollen analysis, LOI, radiocarbon dating, sediment analysis and tephra analysis. Sediment cores were taken from four mires, ranging from the coast to further into the valley, and from three suitable peat bogs one (Viðvík) was identified as most representative and selected as the main site for evaluating climate and environmental changes. The results corresponds well with previous outlined fluctuations, with a transition from a warm and dry climate to a cool and humid climate around 2500 BP. There is no change in the sediment core as a response to human impact during the Landnám phase and the human activities are solely reflected by a distinct peak of the Compositae pollen curve in the uppermost sequence of the sediment core, indicating a settlement period during the years AD 870-930. There is a decrease in the Betula pollen curve together with an increase in the Gramineae pollen curve, several hundred years before the peak of the Compositae pollen curve. This shows that the transition of the landscape from forest-like conditions to a more open environment started well before human settlement, although the subsequent Viking Age and later settlements continued the afforestation trend.

  • 29.
    Johnsen, Timothy F.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Fabel, Derek
    Freeman, Stewart PHT
    New 10Be cosmogenic ages from the Vimmerby moraine confirm the timing of Scandinavian Ice Sheet deglaciation in southern Sweden2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91A, no 2, p. 113-120Article in journal (Refereed)
    Abstract [en]

    The overall pattern of deglaciation of the southern part of the Scandinavian Ice Sheet has been considered established, although details of the chronology and ice sheet dynamics are less well known. Even less is known for the south Swedish Upland because the area was deglaciated mostly by stagnation. Within this area lies the conspicuous Vimmerby moraine, for which we have used the terrestrial cosmogenic nuclide (10Be) exposure dating technique to derive the exposure age of six glacially transported boulders. The six 10Be cosmogenic ages are internally consistent, ranging from 14.9 ± 1.5 to 12.4 ± 1.3 ka with a mean of 13.6 ±0.9 ka. Adjusting for the effects of surface erosion, snow burial and glacio-isostatic rebound causes the mean age to increase only by c. 6% to c. 14.4± 0.9 ka. The 10Be derived age for the Vimmerby moraine is in agreement with previous estimates forthe timing of deglaciation based on radiocarbon dating and varve chronology. This result shows promise for further terrestrial cosmogenic nuclide exposure studies in southern Sweden.

  • 30. Khanchoul, Kamel
    et al.
    Jansson, Margareta B.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Sediment rating curves developed on stage and seasonal means in discharge classes for the Mellah wadi, Algeria2008In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 90A, no 3, p. 227-236Article in journal (Refereed)
    Abstract [en]

    The focus of the present study was to estimate suspended sediment load from the Mellah catchment (550 km(2)) during storms. Suspended sediment rating curves were developed on data from a 23-year period. The regression technique of this paper involves a division of data into discharge-based classes, the mean concentrations and discharges of which are used to develop power regressions through log-transformation. Sediment rating curves were also developed on means of data grouped into seasons and stages. Sediment loads estimated by rating curves uncorrected for bias involved underestimations of down to 9% compared with loads from measured concentrations. Correction for bias reduced underestimations to a range from 0.79 to 3%. Rating curves divided into rising and falling stages had the lowest underestimation and were used to estimate load during periods without concentration measurements. During the 23-year study period, the mean annual suspended sediment yield was 373 T/km(2). Sediment transport is dominated by winter storms accounting for 61% of the annual load. A high exponent 'b' of the power regression equations during the winter season confirms the intense geomorphic work by winter season storms caused by high intensity rainfall, low vegetation cover, and heavy machine activity in the fields.

  • 31.
    Klingbjer, Per
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Recurring jökulhlaups in Sälka, northern Sweden2004In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 86, no 2, p. 169-179Article in journal (Refereed)
    Abstract [en]

    An ice-dammed lake at the margin of the glacier Slkaglaciren, in the Kebnekaise Mountains in northern Sweden, drained suddenly in July 2003 producing a flood with a measured peak discharge of 9.5±0.25 m3s-1. The total lake volume of 4.55×105 million3 drained within two days. The hydrograph of this event is characteristic of a jökulhlaup controlled by a single basal ice tunnel that enlarges due to melting. The jökulhlaup had an exponential rise to a peak discharge, and following the peak, a very steep fall in discharge as the water supply to the drainage system ceased. A similar jökulhlaup was observed in August 1990 with an estimated release of 8.05×105 m3 water. Jökulhlaups at Slkaglaciren are recurring events and have been indirectly observed since the 1950s.

  • 32.
    Lundqvist, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    DEPOSITS FROM LANDSLIDES AND AVALANCHES TRIGGERED BY SEISMIC ACTIVITY IN SWEDISH LAPLAND2010In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 92A, no 3, p. 411-420Article in journal (Refereed)
    Abstract [en]

    In the mountain area of Swedish Lapland, landforms with semicircular or horse-shoe ridges encircling hummocky ground occur They are interpreted as landslide or avalanche deposits directly upon, from or adjacent to down-wasting ice Since they are restricted to the vicinity of fault scarps in the Parvie fault system the releasing factor is suggested to be displacement of bedrock blocks or related seismic activity.

  • 33.
    Lyon, Steve W.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Jantze, Elin J.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Dahlke, Helen E.
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Winterdahl, Mattias
    Stockholm University, Faculty of Science, Department of Physical Geography.
    WHY MONITOR CARBON IN HIGH-ALPINE STREAMS?2016In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 98, no 3, p. 237-245Article in journal (Refereed)
    Abstract [en]

    In this short communication, we report on dissolved organic and inorganic carbon concentrations from a summer stream monitoring campaign at the main hydrological catchment of the Tarfala Research Station in northern Sweden. Further, we place these unique high-alpine observations in the context of a relevant subset of Sweden's national monitoring programme. Our analysis shows that while the monitoring programme (at least for total organic carbon) may have relatively good representativeness across a range of forest coverages, alpine/tundra environments are potentially underrepresented. As for dissolved inorganic carbon, there is currently no national monitoring in Sweden. Since the selection of stream water monitoring locations and monitored constituents at the national scale can be motivated by any number of goals (or limitations), monitoring at the Tarfala Research Station along with other research catchment sites across Fennoscandia becomes increasingly important and can offer potential complementary data necessary for improving process understanding. Research catchment sites (typically not included in national monitoring programmes) can help cover small-scale landscape features and thus complement national monitoring thereby improving the ability to capture hot spots and hot moments of biogeochemical export. This provides a valuable baseline of current conditions in high-alpine environments against which to gauge future changes in response to potential climatic and land cover shifts.

  • 34.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Treml, Vaclav
    Petr, Libor
    Nyplova, Petra
    Snowpatch hollows and pronival ramparts in the krkonoše mountains, Czech Republic: distribution, morphology and chronology of formation2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93A, no 2, p. 137-150Article in journal (Refereed)
    Abstract [en]

    Two types of landforms attributed to the geomorphological effects of long-lasting snow accumulations, snowpatch hollows and pronival ramparts, were studied in the Krkonose Mountains, Czech Republic. Factors influencing the distribution and morphology of snowpatch hollows were examined using statistical analysis of field-measured and DEM-modelled snowpatch hollow characteristics. Snowpatch hollows were classified into two groups. The first group comprises hollows developed mainly in erosional incisions from streams on low-relief summit planation surfaces. The hollows of this group are relatively small and display signs of recent activity, with development during the Holocene. The second group consists of larger snowpatch hollows developed in debris-covered slopes of the highest summits, closely related to the cryoplanation terraces occurring in the area. The hollows of this group are suggested to have developed in the periglacial environment of the glacial periods. The age and degree of activity of pronival ramparts, occurring only at two sites in the study area, were determined using several methods (Schmidt hammer, lichenometry, pollen analysis, and radiocarbon dating). The appearance of these pronival ramparts differs between the two sites as a result of the different geological setting. Both the ramparts in the Harrachova jama cirque, consisting of coarse granite debris, and the rampart in the Upska jama cirque, developed of mica-schist clasts, have been active during the late Holocene and are considered to be active even today.

  • 35. 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.

  • 36. Moscicki, Jerzy
    et al.
    Kotarba, Adam
    Kedzia, Stanislaw
    Glacial erosion in the Abisko Mountains: Karkevagge and Vassivagge, Northern Sweden2006In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 88A, no 2, p. 151-163Article in journal (Refereed)
    Abstract [en]

    This paper discusses direct current resistivity soundings and geomorphological studies of Quaternary deposits in two glacial troughs in the Abisko Mountains of northern Sweden. The subject of the fieldwork is the depth of Pleistocene glacial erosion. Studies were carried out in 1998 and 2003 in the Karkevagge and Vassivagge. The estimated thickness of Quaternary deposits and bedrock properties are discussed in the broader context of glacial erosion studies in the Abisko area. Geophysical and geomorphological studies suggest that the depth of glacial erosion was highly differentiated from -190 m in the Tornetrask basin to the metric overall erosion on the upland plateau. In medium-sized valleys several kilometres long, erosion depth measures 30-50 m. Present-day stream channel patterns reveal a strong relation to the bedrock configuration in valley floors.

  • 37. Mörner, Nils-Axel
    et al.
    Lind, Bob G.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Heimdall's stones at Vitemölla in Sweden and the chronology and stratigraphy of the surroundings2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91A, no 3, p. 205-213Article in journal (Refereed)
    Abstract [en]

    Heimdall's Stones at Vitemolla is an archaeological monument of stones   arranged in circles and where sightlines can be identified of the   sunrise and sunset at winter and summer solstices and spring and autumn   equinoxes. Therefore, this stone monument is likely to have served as   an archaeoastronomic observatory. It is founded in a fossil land   surface now covered by half a metre of eolian sand. In order to date   this sand drift, sediment coring was performed in the nearby Sandefloen   bog. Seven levels were subjected to AMS C14 dating. The first sand   drift, correlated with the sand drift covering Heimdall's Stones, was   dated at 500-600 cal. bc. Consequently, the observatory has to date   back to the Bronze Age, fitting well with its Sun cult and with the   rock carvings recorded on the individual stones. At the seashore 500 m   east of the observatory and the bog, we were able to reconstruct the   sea-level changes. In conclusion, we combine the recorded sea-level   changes with the C14-dated bog stratigraphy and the observed   stratigraphy at Heimdall's Stones (covering an area of 500x500 m) into   one unified picture. The chronostratigraphic position of Heimdall's   Stones agrees well with the dating of the Kivik grave. The Vitemolla   area is likely to have been an important cultural centre in the Bronze   Age.

  • 38.
    Nel, Werner
    et al.
    University of Fort Hare.
    Boelhouwers, Jan
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Zilindile, Mphumzi
    University of Fort Hare.
    The effect of synoptic scale weather systems on sub-surface soil temperatures in a diurnal frost environment: preliminary observations from sub-antarctic Marion Island2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91, no 4, p. 313-319Article in journal (Refereed)
    Abstract [en]

    Marion Island in the South Indian Ocean has a maritime climate dominated by diurnal frost processes in the landscape. We test the hypothesis that synoptic time-scale measurements are essential in understanding the drivers of diurnal frost processes. Preliminary results from automated microclimate measurements in a polar desert habitat show that diurnal soil surface temperatures on Marion Island are influenced by a complex interaction of radiation balance, air mass circulation, cloud cover and snow. The passage of synoptic scale weather systems influences soil thermal characteristics through changes in dominance of the radiation budget. Soil frost on Marion appears to be dependent on clear skies, while synoptic weather systems affect the duration and intensity of soil frost processes and non-radiative heat fluxes. Air circulation patterns at Marion Island influence diurnal scale temperature fluctuations and its direct and indirect interactions with ecosystem processes. The data suggest that in a maritime sub-Antarctic environment the climatic drivers of soil frost occur at a finertemporal resolution than for seasonal and permafrost environments and needs to be measured at a diurnal time-scale to be meaningful.

  • 39.
    Nihlen, Tomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Palsas in Harjedalen, Sweden: 1910 and 1998 compared2000In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 82A, no 1, p. 39-44Article in journal (Refereed)
    Abstract [en]

    In 1998 on area near Helagsfjallet in Harjedalen was investigated in an attempt to relocate palsas discovered by the botanist Harry Smith in 1910. Several small palsa-like features with ice cores were detected. The palsas were found on an almost flat peat bog at 950 m, 3 km NW of NL Helagsfjallet. Five clearly elevated mounds and some indistinct ones with palsa-like features were traced. The Five mounds were about 0.6 m high and had an area of about 2 x 3 m. One of the mounds was examined in more detail. At a depth of 0.3 m in the peat an ice body with 3 hard ice core was found. This location is the most southerly area known with occurrence of palsa-like forms in Sweden at the present time. In spite of a warmer climate towards the latter part of this century, palsa-like features have survived in this area. The mean annual temperature barely fits the criterion for palsa formation while the mean annual precipitation is too high as compared with the general assumptions. The palsa formation is probably dependent on strong winds thinning out the snowcover.

  • 40.
    Nohrstedt, Daniel
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Government.
    Nyberg, Lars
    Karlstad Universitet.
    Do Floods Drive Crisis Mitigation Policy?: Evidence from Swedish Municipalities2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 109-122Article in journal (Refereed)
    Abstract [en]

    It is well established that continuous development of local-level mitigation policy plans and actions increases the chances of effective responses to natural hazards. What is less well known is how and why policy development, including the scope and pace of changes in municipality crisis mitigation programs, varies across local-level crisis mitigation systems. Using survey data on municipality hazard mitigation policy in Sweden, this study documents patterns of policy development and explores candidate explanations. Special attention is devoted to floods, which present local managers with opportunities to learn and adjust local mitigation policies. To investigate floods along with other hazards as potential drivers for local mitigation policy, the study examines three approaches to policy development: external shocks, transformation without disruption, and regional diffusion. Overall, in this case, the transformation without disruption model and the regional diffusion model do better than the external shocks model. Important precursors of policy development include collaboration, learning and diffusion effects from events and policy adoption in nearby municipalities. The study demonstrates the value of a broader analytical approach to policy development, which takes into account the interplay between events, collaborative management, and learning.

  • 41.
    Nohrstedt, Daniel
    et al.
    Uppsala Univ, Dept Govt, SE-75120 Uppsala, Sweden.;Uppsala Univ, CNDS, SE-75120 Uppsala, Sweden..
    Nyberg, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Centre for Climate and Safety.
    Do floods drive hazard mitigation policy?: Evidence from swedish municipalities2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 109-122Article in journal (Refereed)
    Abstract [en]

    It is well established that continuous development of local-level mitigation policy plans and actions increases the chances of effective responses to natural hazards. What is less well known is how and why policy development, including the scope and pace of changes in municipality crisis mitigation programs, varies across local-level crisis mitigation systems. Using survey data on municipality hazard mitigation policy in Sweden, this study documents patterns of policy development and explores candidate explanations. Special attention is devoted to floods, which present local managers with opportunities to learn and adjust local mitigation policies. To investigate floods along with other hazards as potential drivers for local mitigation policy, the study examines three approaches to policy development: external shocks, transformation without disruption, and regional diffusion. Overall, in this case, the transformation without disruption model and the regional diffusion model do better than the external shocks model. Important precursors of policy development include collaboration, learning and diffusion effects from events and policy adoption in nearby municipalities. The study demonstrates the value of a broader analytical approach to policy development, which takes into account the interplay between events, collaborative management, and learning.

  • 42.
    Nyberg, Alf
    SMHI.
    SOME VIEWS ON THE WATER LEVEL IN LAKE MALAREN AND IN THE ADJACENT BALTIC SEA1987In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 69, no 2, p. 271-282Article in journal (Refereed)
  • 43.
    Nyberg, Rolf
    et al.
    Karlstad University, Faculty of Social and Life Sciences, Department of Geography and Tourism. Karlstad University, Faculty of Social and Life Sciences, Centre for Climate and Safety.
    Ridefelt, H
    Åkerman, J
    Beylich, A.A
    Boelhouwers, J
    Kolstrup, E
    56 years of solifluction measurements in the Abisko Mountains, northern Sweden-: analysis of temporal and spatial variations of slow soil surface movement2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91, no 3, p. 215-232Article in journal (Refereed)
    Abstract

    Solifluction movement rates from 1952 to 2008 for the Abisko region, N Sweden, have been compiled and analysed through correlation tests and multiple regression. It is concluded that movement rates may increase with high mean annual air temperature in the western part of the region, the spatial variability of movement rates within the region is very high and that altitude (and/or permafrost) together with wetness index are the main controls on the regional spatial variation. The study highlights the limitations in establishing statistical relationships between movement rates and climate using data from different field empirical studies

  • 44.
    Olauson, Jon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Goude, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bergkvist, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Wind Energy Converters and Photovoltaics for Generation of Electricity after Natural Disasters2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 9-23Article in journal (Refereed)
    Abstract [en]

    During recovery and reconstruction after a natural disaster, an autonomous power supply might be needed for an extended period of time. In this work, the feasibility of using small-scale wind power and battery storage for power supply is evaluated and compared with systems containing photovoltaics. The investment cost per yearly produced kWh and for an optimized energy system supplying small loads (2 or 20 kW peak) has been calculated for 32 sites, predominantly in Africa and the Middle East. The sites represent foreign activities of the Swedish Civil Contingencies Agency at the end of 2012.

    Since wind speed measurement series often have a lot of missing data, autoregressive moving average models were trained and used to generate hourly time series of wind speed. This methodology proved robust, even when data availability was very low or when measurements were only taken every third hour. The results of the simulations show that photovoltaic/battery systems outperform wind/battery systems at all evaluated sites. This can be explained by lower investment cost per yearly produced kWh and smoother daily/weekly power output over the year for the photovoltaic system. The proportion of wind power for optimized systems comprising wind, photovoltaics and battery bank is generally very low and the system cost is almost identical to the corresponding photovoltaic/battery systems. In conclusion, at lower latitudes and with little time for a proper wind measurement campaign, photovoltaics should be the primary candidate for replacing or complementing conventional diesel generators.

  • 45.
    Ostwald, Madelene
    et al.
    Linköping University, The Tema Institute, Centre for Climate Science and Policy Research . Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Simelton, Elisabeth
    Göteborg University.
    Chen, Deliang
    Göteborg University.
    Liu, Ann
    Shaanxi Remote Sensing Centre for Agriculture.
    Relation between vegetation changes, climate variables and land-use policy in Shaanxi Province, China2007In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 89, no 4, p. 223-236Article in journal (Refereed)
    Abstract [en]

    Shaanxi Province in China has been exposed to climate variability and dramatic land-use policies. The aim here is to examine vegetation changes in this area on a regional scale from 2000 to 2004 in relation to land-use changes and climate traits. The data in this assessment include remote sensing information from moderate-resolution imaging spectro-radiometer normalized difference vegetation index from 2000 to 2004, and climate data (precipitation and temperature) from 1956 to 2000. The results show an increase in vegetation production from 2000 to 2004, particularly in the north, which cannot be explained solely by climate impacts. Since the vegetation in the north is more dependent on climate variation than the other parts of Shaanxi due to more serious water limitation, the results suggest that the large-scale land-use policy implemented over the last decade, with a focus on northern Shaanxi, is possibly having an impact on the overall vegetation.

  • 46.
    Parker, Charles
    Swedish National Defence College, Department of Security, Strategy and Leadership (ISSL), CRISMART (National Center for Crisis Management Research and Training). Uppsala universitet.
    Complex Negative Events and the Diffusion of Crisis: Lessons from the 2010 and 2011 Icelandic Volcanic Ash Cloud Events2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 97-108Article in journal (Refereed)
    Abstract [en]

    In a world characterized by complex interdependence, crises that originate in one country have the potential to rapidly diffuse across borders and have profound regional and even global impacts. The eruption of the Icelandic volcano Eyjafjallajökull in April 2010 demonstrates how rapidly a natural disaster can morph from a local crisis with local effects to a cascading crisis with international effects across multiple sectors. After spreading to Europe the ash cloud severely disrupted air travel and paralyzed the European aviation transport system. This cascading crisis caught authorities by surprise and revealed the need to improve crisis preparedness to deal with the threat of volcanic ash in particular and aviation in general at the international, EU, and national levels. In the aftermath of the event, reforms and policy changes ensued. Just over a year later, the Icelandic volcano Grímsvötn erupted, providing an opportunity to observe the revised system respond to a similar event. The origins, response, reforms, lessons learned, and questions of resilience connected to these complex negative events are the subject of this paper. The article concludes by addressing the question of whether and to what extent the vulnerabilities and problems exposed by the 2010 volcanic ash cloud event are amenable to reform.

  • 47.
    Parker, Charles F.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Government.
    Complex Negative Events and the Diffusion of Crisis: Lessons from the 2010 and 2011 Icelandic Volcanic Ash Cloud Events2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 97-108Article in journal (Refereed)
    Abstract [en]

    In a world characterized by complex interdependence, crises that originate in one country have the potential to rapidly diffuse across borders and have profound regional and even global impacts. The eruption of the Icelandic volcano Eyjafjallajokull in April 2010 demonstrates how rapidly a natural disaster can morph from a local crisis with local effects to a cascading crisis with international effects across multiple sectors. After spreading to Europe the ash cloud severely disrupted air travel and paralyzed the European aviation transport system. This cascading crisis caught authorities by surprise and revealed the need to improve crisis preparedness to deal with the threat of volcanic ash in particular and aviation in general at the international, EU, and national levels. In the aftermath of the event, reforms and policy changes ensued. Just over a year later, the Icelandic volcano Grimsvotn erupted, providing an opportunity to observe the revised system respond to a similar event. The origins, response, reforms, lessons learned, and questions of resilience connected to these complex negative events are the subject of this paper. The article concludes by addressing the question of whether and to what extent the vulnerabilities and problems exposed by the 2010 volcanic ash cloud event are amenable to reform.

  • 48. Pettersson, R.
    et al.
    Christoffersen, P.
    Dowdeswell, J. A.
    Pohjola, V. A.
    Hubbard, A.
    Strozzi, T.
    ICE THICKNESS AND BASAL CONDITIONS OF VESTFONNA ICE CAP, EASTERN SVALBARD2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93AArticle in journal (Refereed)
    Abstract [en]

    We combined ground-based pulsed radar data collected in 20082009 with airborne radio-echo sounding data acquired in 1983 and 1986 over Vestfonna ice cap, Svalbard. The airborne dataset mainly covers the fast-flowing outlet glaciers and the marginal zone, while the ground-based data explicitly cover the interior part of the ice cap. The data presented here are thus the first complete estimate of bed topography and ice thickness. The subglacial landscape undulates with elevations between -160 and +410 m above sea level. The mean ice thickness is 186 m and the total ice area and volume are 2402 km2 and 442 +/- 0.6 km3, respectively. This is a much smaller volume than those derived from empirical volume-area scaling relationships currently used to estimate regional-to-global glacier volumes. This difference may depend on local conditions for Vestfonna and emphasizes the need to include more volume observations in the derivations of volume-area scaling parameters. We also derive basal reflectivity as a proxy for thermal conditions at the bed. Basal reflectivity values suggest that fast-flowing outlet glaciers are underlain by temperate conditions. The geometric boundaries and basal conditions for Vestfonna will be critical additions to the development of numerical models of the ice cap and to the estimation of more accurate area-volume scaling parameters.

  • 49.
    Pettersson, Rickard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Christoffersen, Poul
    Dowdeswell, Julian A.
    Pohjola, Veijo A
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Hubbard, Alun
    Strozzi, Tazio
    Ice thickness and basal conditions of Vestfonna ice cap, eastern Svalbard2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93A, no 4, p. 311-322Article in journal (Refereed)
    Abstract [en]

    We combined ground-based pulsed radar data collected in 20082009 with airborne radio-echo sounding data acquired in 1983 and 1986 over Vestfonna ice cap, Svalbard. The airborne dataset mainly covers the fast-flowing outlet glaciers and the marginal zone, while the ground-based data explicitly cover the interior part of the ice cap. The data presented here are thus the first complete estimate of bed topography and ice thickness. The subglacial landscape undulates with elevations between -160 and +410 m above sea level. The mean ice thickness is 186 m and the total ice area and volume are 2402 km2 and 442 +/- 0.6 km3, respectively. This is a much smaller volume than those derived from empirical volume-area scaling relationships currently used to estimate regional-to-global glacier volumes. This difference may depend on local conditions for Vestfonna and emphasizes the need to include more volume observations in the derivations of volume-area scaling parameters. We also derive basal reflectivity as a proxy for thermal conditions at the bed. Basal reflectivity values suggest that fast-flowing outlet glaciers are underlain by temperate conditions. The geometric boundaries and basal conditions for Vestfonna will be critical additions to the development of numerical models of the ice cap and to the estimation of more accurate area-volume scaling parameters.

  • 50. Pohjola, V. A.
    et al.
    Christoffersen, P.
    Kolondra, L.
    Moore, J. C.
    Pettersson, R.
    Schafer, M.
    Strozzi, T.
    Reijmer, C. H.
    SPATIAL DISTRIBUTION AND CHANGE IN THE SURFACE ICE-VELOCITY FIELD OF VESTFONNA ICE CAP, NORDAUSTLANDET, SVALBARD, 1995-2010 USING GEODETIC AND SATELLITE INTERFEROMETRY DATA2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93AArticle in journal (Refereed)
    Abstract [en]

    During 2007 we launched a geodetic campaign on the Svalbard ice cap Vestfonna in order to estimate the velocity field of the ice cap. This was done within the frame of the IPY project KINNVIKA. We present here the velocity measurements derived from our campaigns 20072010 and compare the geodetic measurements against InSAR velocity fields from satellite platforms from 1995/96 and 2008. We find the spatial distribution of ice speeds from the InSAR is in good agreement within the uncertainty limits with our geodetic measurements. We observe no clear indication of seasonal ice speed differences, but we find a speed-up of the outlet glacier Franklinbreen between the InSAR campaigns, and speculate the outlet is having a surge phase.

12 1 - 50 of 68
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