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  • 51. 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.

  • 52.
    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.

  • 53. 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.

  • 54.
    Pohjola, Veijo A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Christoffersen, Poul
    Kolondra, Leszek
    Moore, John C.
    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.
    Schäfer, Martina
    Strozzi, Tazio
    Reijmer, Carleen 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. 93, no 4, p. 323-335Article 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 2007–2010 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.

  • 55.
    Pohjola, Veijo A.
    et al.
    Uppsala Univ, Dept Earth Sci, S-75236 Uppsala, Sweden.;Uppsala Univ, Dept Earth Sci Air Water & Landscape Sci, S-75236 Uppsala, Sweden..
    Kankaanpaa, Paula
    Univ Lapland, Arctic Ctr, FI-96101 Rovaniemi, Finland..
    Moore, John C.
    Univ Lapland, Arctic Ctr, FI-96101 Rovaniemi, Finland.;Beijing Normal Univ, Coll Global Change & Earth Syst Sci, Beijing 100875, Peoples R China.;Uppsala Univ, Dept Earth Sci Air Water & Landscape Sci, S-75236 Uppsala, Sweden..
    Pastusiak, Tadeusz
    Gdynia Maritime Univ, PL-81345 Gdynia, Poland..
    PREFACE: THE INTERNATIONAL POLAR YEAR PROJECT KINNVIKA'- ARCTIC WARMING AND IMPACT RESEARCH AT 80 degrees N2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93A, no 4, p. 201-208Article in journal (Other academic)
  • 56.
    Pohjola, Veijo A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Moore, John C
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Kankaanpää, P.
    Arctic Centre, University of Lapland, Rovaniemi, Finland .
    Pastusiak, Tadeusz
    Gdynia Maritime University, Gdynia, Poland.
    Preface: The international polar year project ‘Kinnvika’ – Arctic warming and impact research at 80 °N2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93, no 4, p. 201-208Article in journal (Refereed)
  • 57. Pohjola, Veijo
    et al.
    Cole-Dai, Jiang
    Rosqvist, Gunhild
    Stroeven, Arjen
    Thompson, Lonnie
    Potential to recover paleoclimatic data in temperate ice cores: an example from the small ice cap Riukojietna, Northern Scandinavia2005In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 87, no 1, p. 259-270Article in journal (Refereed)
    Abstract [en]

    We have studied a 33.7 m deep ice core from a small polythermal Scandinavian ice cap to determine whether it is possible to recover pre-20th century climatic information from the glacier. Ice structural studies show a significant change from clear ice above 11 m depth (superimposed ice indicating refreezing) to bubbly ice below 11 m depth, indicating this is the transition between Little Ice Age (LIA) and 20th century ice. Calculations with a Nye-age model, along with a mass balance reconstruction, show that this structural boundary likely formed in the last part of the LIA, which in this region ended about 1910. The ice below this boundary was sampled and analyzed for stable isotopic composition and ionic content, which both show significant variations with depth. The stable isotope record likely contains cycles of annual duration during the LIA. The chemistry in the ice core indicates that the information is useful, and can be used to interpret climatic and environmental variables during the LIA. A comparison of Riukojietna ion chemistry and oxygen isotope records to similar records from other glaciers in this region reveals a clear continental – maritime gradient. Changes in this gradient with time may be possible to resolve using such ice core records. Results from this study demonstrate that ice cores from glaciers in this climatic environment can be useful in revealing environmental conditions from climatically colder periods and yield pre-industrial benchmark values for chemical loading and oxygen isotopes, but that hiatuses complicate the depth-age relationship.

  • 58.
    Pohjola, Veijo
    et al.
    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.
    Cole-Dai, Jiang
    Rosqvist, Gunhild
    Stroeven, Arjen
    Thompson, Lonnie
    Potential to recover paleoclimatic data in temperate ice cores: an example from the small ice cap Riukojietna, Northern Scandinavia2005In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 87, no 1, p. 259-270Article in journal (Refereed)
    Abstract [en]

    We have studied a 33.7 m deep ice core from a small polythermal Scandinavian ice cap to determine whether it is possible to recover pre-20th century climatic information from the glacier. Ice structural studies show a significant change from clear ice above 11 m depth (superimposed ice indicating refreezing) to bubbly ice below 11 m depth, indicating this is the transition between Little Ice Age (LIA) and 20th century ice. Calculations with a Nye-age model, along with a mass balance reconstruction, show that this structural boundary likely formed in the last part of the LIA, which in this region ended about 1910. The ice below this boundary was sampled and analyzed for stable isotopic composition and ionic content, which both show significant variations with depth. The stable isotope record likely contains cycles of annual duration during the LIA. The chemistry in the ice core indicates that the information is useful, and can be used to interpret climatic and environmental variables during the LIA. A comparison of Riukojietna ion chemistry and oxygen isotope records to similar records from other glaciers in this region reveals a clear continental – maritime gradient. Changes in this gradient with time may be possible to resolve using such ice core records. Results from this study demonstrate that ice cores from glaciers in this climatic environment can be useful in revealing environmental conditions from climatically colder periods and yield pre-industrial benchmark values for chemical loading and oxygen isotopes, but that hiatuses complicate the depth-age relationship.

  • 59. Ridefelt, Hanna
    et al.
    Åkerman, Jonas
    Beylich, Achim A
    Boelhouwers, Jan
    Kolstrup, Else
    Nyberg, Rolf
    56 years of solifluction measurements in the abisko mountains, northern sweden – analysis of temporal and spatial variations of slow soil surface movement AU - Ridefelt, Hanna2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91, no 3, p. 215-232Article in journal (Refereed)
    Abstract [en]

    Abstract.Solifluction movement rates from 1952 to 2008 for the Abisko region, northern Sweden, have been compiled and analysed through correlation tests and multiple regression. The temporal analysis is based on two datasets (Lobe11 & gridAB and Line B) from Kärkevagge. The dataset Lobe11 & gridAB show a strong correlation between movement rates and mean annual air temperature (MAAT) and MAAT is also identified as one of the significant contributing parameters in the multiple regression model. No significant correlations were found for the Line B dataset. The spatial analysis indicates generally higher movement rates in the western part of the region and at lower altitudes mainly between 700 and 900 m a.s.l., but the spatial variability is high. To reduce the influence of the temporal variation the data for the correlation tests of the spatial variations were divided into two parts: 1957 to 1980 and 1981 to 2008. The correlation analysis of the dataset 1957 to 1980 shows a significant negative correlation between annual average movement rates and permafrost probability and altitude. The dataset 1981 to 2008 shows a positive correlation between movement rates and wetness index. It is concluded that movement rates may increase with higher MAAT in the western part of the region (Kärkevagge), 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.

  • 60.
    Ridefelt, Hanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Åkerman, Jonas
    Department of Physical Geography and Ecosystems Analysis, Lund University, Sweden.
    Beylich, Achim
    Quaternary Geology and Climate group, Geological Survey of Norway; Department of Geography, Trondheim & Norwegian University of Science and Technology, Norway.
    Boelhouwers, Jan
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Kolstrup, Else
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Nyberg, Rolf
    Department of Geography and Tourism, Karlstad University, Sweden.
    56 years of solifluction measurements in the Abisko Mountains, northern Sweden: analysis of spatial and temporal variations of slow soil surface movements2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91, no 3, p. 215-232Article in journal (Refereed)
    Abstract [en]

    Solifluction movement rates from 1952 to 2008 for the Abisko region, northern Sweden, have been compiled and analysed through correlation   tests and multiple regression. The temporal analysis is based on two   datasets (Lobe11 & gridAB and Line B) from Karkevagge. The dataset   Lobe11 & gridAB show a strong correlation between movement rates and   mean annual air temperature (MAAT) and MAAT is also identified as one   of the significant contributing parameters in the multiple regression   model. No significant correlations were found for the Line B dataset.   The spatial analysis indicates generally higher movement rates in the   western part of the region and at lower altitudes mainly between 700   and 900 m a.s.l., but the spatial variability is high. To reduce the   influence of the temporal variation the data for the correlation tests   of the spatial variations were divided into two parts: 1957 to 1980 and   1981 to 2008. The correlation analysis of the dataset 1957 to 1980   shows a significant negative correlation between annual average   movement rates and permafrost probability and altitude. The dataset   1981 to 2008 shows a positive correlation between movement rates and   wetness index. It is concluded that movement rates may increase with   higher MAAT in the western part of the region (Karkevagge), 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.

  • 61.
    Ryden, Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Applied Mathematics and Statistics.
    A Statistical Analysis of Trends for Warm and Cold Spells in Uppsala by Means of Counts2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 3, p. 431-436Article in journal (Refereed)
    Abstract [en]

    Statistical studies of extremes are of interest in the climatic sciences, in particular trends of periods of unusually warm or cold weather, which could be labelled warm and cold spells, respectively. We study the yearly number of spells in Uppsala, Sweden which from a data-analytic point of view truly are counts, and employ theory and methods from the field of regression models for counts. A possible trend for the period 1840-2012 was investigated. The trend for warm spells is positive and demonstrated to be larger in magnitude compared with the one for cold spells, and is found to be statistically significant. The methodology could be extended to analyse other climate indicators.

  • 62.
    Soto Gómez, Agnes Jane
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Rodhe, Allan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Pohjola, Veijo
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Boelhouwers, Jan
    Spatial Distribution of Disasters Caused by Natural Hazards in the Samala River Catchment, Guatemala2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 181-196Article in journal (Refereed)
    Abstract [en]

    Understanding the conditions of the locations where disasters are reported and applying that knowledge to disaster risk reduction actions is essential and especially needed on the local scale. This study assessed how important the physical configuration is as cause of disasters by studying the links between the locations where disasters have been reported and the physical attributes of those locations. The Samala River catchment in Guatemala was used as a case study because it is a relatively small but complex area exposed to multiple natural hazards. Disasters of hydro-meteorological origin were addressed for the study because they are the most frequent type of disasters reported in the area. The method proposed in this work classified the study area into geomorphological units that were used to analyze where disasters were reported, the physical conditions of the particular locations of disaster reports, and to what degree disasters are spatially linked to slope and temporally to precipitation. We found that analyzing the study area based on the geomorphological configuration was useful and allowed analyses on comparatively homogeneous zones and to hypothesize on the particular geomorphological processes related to the occurrences of disasters. For steep geomorphological units we found a clear spatial relationship between the number of disasters reported and the slope of the locations, with higher frequency of disasters in the less sloping areas of the unit. The need to consider social factors for understanding this relationship was emphasized. As expected there was a very strong temporal relationship between disaster occurrence and wetness, as estimated from the antecedent rainfall, with high risk for disaster at high wetness. The applied methodological approach provides a tool for disaster research on physically complex areas, which is common to active tectonic and volcanic regions.

  • 63. Stouge, Svend
    et al.
    Christiansen, Jorgen Loye
    Holmer, Lars Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Lower palaeozoic stratigraphy of Murchisonfjorden and Sparreneset, Nordaustlandet, Svalbard2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93, no 4, p. 209-226Article in journal (Refereed)
    Abstract [en]

    The Lower Palaeozoic stratigraphy of the Kap Sparre Formation of Kulling (Hecla Hoek Succession) from Murchisonfjorden and eastern Nordaustlandet of Svalbard is described based on new field observations in the region. The investigated sedimentary succession is referred to the Upper quartzite series and Upper dolomite series of the Kap Sparre Formation. The observed sequence resembles that of the Oslobreen Group from central and northeastern Ny Friesland and the formal and well-established and more detailed stratigraphical framework used in Ny Friesland may apply for the strata at Sparreneset and in Murchisonfjorden, western Nordaustlandet. The lower Palaeozoic succession overlies the uppermost Precambrian sediments (Dracoisen Formation = the lower part of Kap Sparre Formation sensu Kulling) of the Polarisbreen Group with a cryptic unconformity, and a regional stratigraphical gap spanning the late Ediacaran developed on the platform. Additions to the previous descriptions of some of the existing units are presented. The new lithostratigraphical unit: Black shale and limestone unit is proposed informally. It is a Lower(?) to Middle Cambrian black shale with limestone nodules and lenses that is exposed on the northwest coast of Krossoya in Murchisonfjorden, Svalbard. In addition, a Dolostone-limestone unit, Middle(?) Cambrian to Lower Ordovician, composed of dolostone and dolomitized limestone and minor limestone, and a Limestone unit (Lower to Middle(?) Ordovician), which overlies the Upper dolomite series are added to the succession. The deposits as a whole show the development of an environmentally controlled carbonate platform that marked the transition from the inner to the outer shelf that evolved during the opening and spreading of the Iapetus Ocean.

  • 64.
    Strömquist, Lennart
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Integrated landscape analyses of change of miombo woodland in Tanzania and its implication for environment and human livelihood2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91A, no 1, p. 31-45Article in journal (Refereed)
    Abstract [en]

    Landscapes bear witness to past and present natural and societal processes influencing the environment and human livelihoods. By analysing landscape change at different spatial scales over time the effects on the environment and human livelihoods of various external and internal driving forces of change can be studied. This paper presents such an analysis of miombo woodland surrounding the Mkata plains in central Tanzania. The rich natural landscape diversity of the study area in combination with its historical and political development makes it an ideal observation ground for this kind of study. The paper focuses on long-term physical and biological changes, mainly based on satellite information but also on field studies and a review of documents and literature.

    The miombo woodlands are highly dynamic semi-arid ecosystems found on a number of nutrient-poor soil groups. Most of the woodlands are related to an old, low-relief geomorphology of erosion surfaces with relatively deep and leached soils, or to a lesser extent also on escarpments and steep Inselberg slopes with poor soils. Each period in the past has cast its footprints on the landscape development and its potential for a sustainable future use. On a regional level there has been a continual decrease in forest area over time. Expansion of agriculture around planned villages, implemented during the 1970s, in some cases equals the loss of forest area (Mikumi-Ulaya), whilst in other areas (Kitulangalo), the pre-independence loss of woodland was small; the agricultural area was almost the same during the period 1975–1999, despite the fact that forests have been lost at an almost constant rate over the same period. Illegal logging and charcoal production are likely causes because of the proximity to the main highway running through the area. Contrasting to the general regional pattern are the conditions in a traditional village (Ihombwe), with low immigration of people and a maintained knowledge of the resource potential of the forest with regards to edible plants and animals. In this area the local community has control of the forest resources in a Forest Reserve, within which the woody vegetation has increased in spite of an expansion of agriculture on other types of village land. The mapping procedure has shown that factors such as access to transport and lack of local control have caused greater deforestation of certain areas than during the colonial period. Planned villages have furthermore continued to expand over forest areas well after their implementation, rapidly increasing the landscape fragmentation. One possible way to maintain landscape and biodiversity values is by the sustainable use of traditional resources, based on local knowledge of their management as illustrated by the little change observed in the traditionally used area.

  • 65. Sugden, David E.
    et al.
    Hall, Adrian M.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Phillips, William M.
    Stewart, Margaret A.
    Plucking enhanced beneath ice sheet margins: evidence from the Grampian Mountains, Scotland2019In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 101, no 1, p. 34-44Article in journal (Refereed)
    Abstract [en]

    Concentrations of boulders are a common feature of landscapes modified by former mid-latitude ice sheets. In many cases, the origin of the boulders can be traced in the up-ice direction to a cliff only tens to hundreds of metres distant. The implication is that a pulse of plucking and short boulder transport occurred beneath thin ice at the end of the last glacial cycle. Here we use a case study in granite bedrock in the Dee Valley, Scotland, to constrain theory and explore the factors involved in such a late phase of plucking. Plucking is influenced by ice velocity, hydrology, effective ice pressure, the extent of subglacial cavities and bedrock characteristics. The balance between these factors favours block removal beneath thin ice near a glacier margin. At Ripe Hill in the Dee Valley, a mean exposure age of 14.2 ka on blocks supports the view that the boulder train formed at the end of ice sheet glaciation. The late pulse of plucking was further enhanced by ice flowing obliquely across vertical joints and by fluctuations in sub-marginal meltwater conditions. An implication of the study is that there is the potential for a wave of ice-marginal plucking to sweep across a landscape as an ice sheet retreats.

  • 66. Sundborg, A
    et al.
    Calles, Bengt
    Linköping University, Faculty of Arts and Sciences. Linköping University, The Tema Institute.
    Water discharges determined from sediment distributions: A palaeohydrological method2001In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 83A, no 1-2, p. 39-54Article in journal (Refereed)
    Abstract [en]

    The article presents a simple sediment deposition model, based on current knowledge of the processes of transport and deposition of suspended material. It indicates possibilities of interpreting flow conditions from grain-size distributions at two localities, situated along the water flowline. The model reveals new information an ancient hydrological and sedimentological processes and events. Previously the model has been applied to forecast trap efficiency of reservoirs and predict reservoir sedimentation. In this study the model is used as a palaeohydrological method in studies of annual varves. In varve geochronology a major attention has been paid to varve correlations and valve thickness variations, whereas other sedimentological data have been more or less disregarded. In this article new information on the spatial distribution of particle sizes demonstrate that further knowledge can be gained by careful studies of the patterns of grain-size distributions. Annual variations in water discharges during late glacial time were studied in the Indalsalven and Dalalven valleys in Sweden. Water discharges during the deglaciation seem to have been of the same order of magnitude as in present-day rivers during normal years. During some years catastrophic events occurred, resulting in exceptional water discharges. The magnitudes of these discharges were estimated, and drainage directions were established. It appears from the studies that there are promising prospects of finding out both the magnitude and frequency of processes that until now have been described only in qualitative terms.

  • 67.
    Sundqvist, Hanna S.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Baker, A
    Holmgren, Karin
    Luminescence in fast growing stalagmites from Uppsala, Sweden2005In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 87, no 4, p. 539-548Article in journal (Refereed)
    Abstract [en]

    Two fast-growing stalagmites from a cellar vault in Uppsala, southeast Sweden, are ana-lysed for their luminescent properties. The results

    indicate that variations in luminescence intensity in the stalagmites are annual. Due to problems in find-ing a suitable absolute dating method this assump-tion cannot yet be firmly tested; however, results from radiocarbon dating of one of the stalagmites do not contradict the proposal that the laminae are annual. If so, the speleothems have been growing for 10-15 years with a growth rate of 3-8 mm per year, which is a similar rate to other fast-growing speleothems in Great Britain that have formed from the reaction of lime mortar and carbon dioxide. It is likely that the assumed annual laminae of the lumi-nescence record represent a flush of organic mate-rial.

  • 68.
    Troll, Valentin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Deegan, Frances
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Jolis, Ester Muños
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Budd, David
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Dahrén, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Schwarzkopf, L.M.
    Ancient oral tradition describes volcano-earthquake interaction at Merapi volcano, Indonesia.2015In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, no 1, p. 137-166Article in journal (Refereed)
  • 69.
    Vedin, Haldo
    SMHI.
    FREQUENCY OF RARE WEATHER EVENTS DURING PERIODS OF EXTREME CLIMATE1990In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 72, no 2, p. 151-155Article in journal (Refereed)
  • 70.
    Vedin, Haldo
    et al.
    SMHI.
    Eklund, Anna
    SMHI, Core Services.
    Alexandersson, Hans
    SMHI.
    The rainstorm and flash flood at Mount Fulufjallet in August 1997: The meteorological and hydrological situation1999In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 81A, no 3, p. 361-368Article in journal (Refereed)
    Abstract [en]

    The flood at Mount Fulufjallet, 30-31 August 1997 was caused by the most furious rainstorm ever documented in Sweden. Private measurements on the mountain show nor less than 276 mm over 24 hours, and the distribution of severe damage suggests even higher amounts in other parts of the mountain. The precipitation was connected to a front attacking a high pressure that had been dominating the weather in Sweden for several weeks, but orographic lifting on the east-facing slopes of the mountain may partly have caused the extreme intensity. In River Fulan. one of the upper branches of River Dalalven, the discharge peaked at a diurnal mean value of 233 m(3)/s, the highest since measurements began in 1913. At the stream Tangan and the new common outlet of the streams Store and Lilla Goljan, both locations with a normal discharge of only around 1 m(3)/s, instantaneous values of approximately 300 m(3)/s have been estimated, corresponding to values close to the normal discharge at the mouth of River Dalalven on the coast of the Sea of Bothnia.

  • 71.
    Vogel, Hendrik
    et al.
    Institute of Geological Sciences, University of Bern, Bern, Switzerland.
    Wagner, Bernd
    Institute of Geology and Mineralogy, University of Cologne, Köln, Germany.
    Rosen, Peter
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lake Floor Morphology and Sediment Architecture of Lake Tornetrask, Northern Sweden2013In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 95, no 2, p. 159-170Article in journal (Refereed)
    Abstract [en]

    Here we present datasets from a hydroacoustic survey in July 2011 at Lake Tornetrask, northern Sweden. Our hydroacoustic data exhibit lake floor morphologies formed by glacial erosion and accumulation processes, insights into lacustrine sediment accumulation since the beginning of deglaciation, and information on seismic activity along the Parvie Fault. Features of glacial scouring with a high-energy relief, steep slopes, and relative reliefs of more than 50m are observed in the large W-basin. The remainder of the lacustrine subsurface appears to host a broad variety of well preserved formations from glacial accumulation related to the last retreat of the Fennoscandian ice sheet. Deposition of glaciolacustrine and lacustrine sediments is focused in areas situated in proximity to major inlets. Sediment accumulation in distal areas of the lake seldom exceeds 2m or is not observable. We assume that lack of sediment deposition in the lake is a result of different factors, including low rates of erosion in the catchment, a previously high lake level leading to deposition of sediments in higher elevated paleodeltas, tributaries carrying low suspension loads as a result of sedimentation in upstream lakes, and an overall low productivity in the lake. A clear off-shore trace of the Parvie Fault could not be detected from our hydroacoustic data. However, an absence of sediment disturbance in close proximity to the presumed fault trace implies minimal seismic activity since deposition of the glaciolacustrine and lacustrine sediments.

  • 72. Vogel, Hendrik
    et al.
    Wagner, Bernd
    Rosén, Peter
    Lake floor morphology and sediment architecture of lake torneträsk, northern sweden2013In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 95, no 2, p. 159-170Article in journal (Refereed)
    Abstract [en]

    AbstractHere we present datasets from a hydroacoustic survey in uly 2011 at Lake orneträsk, northern weden. Our hydroacoustic data exhibit lake floor morphologies formed by glacial erosion and accumulation processes, insights into lacustrine sediment accumulation since the beginning of deglaciation, and information on seismic activity along the Pärvie Fault. Features of glacial scouring with a high?energy relief, steep slopes, and relative reliefs of more than 50 m are observed in the large ?basin. The remainder of the lacustrine subsurface appears to host a broad variety of well preserved formations from glacial accumulation related to the last retreat of the Fennoscandian ice sheet. Deposition of glaciolacustrine and lacustrine sediments is focused in areas situated in proximity to major inlets. Sediment accumulation in distal areas of the lake seldom exceeds 2 m or is not observable. We assume that lack of sediment deposition in the lake is a result of different factors, including low rates of erosion in the catchment, a previously high lake level leading to deposition of sediments in higher elevated paleodeltas, tributaries carrying low suspension loads as a result of sedimentation in upstream lakes, and an overall low productivity in the lake. A clear off?shore trace of the Pärvie Fault could not be detected from our hydroacoustic data. However, an absence of sediment disturbance in close proximity to the presumed fault trace implies minimal seismic activity since deposition of the glaciolacustrine and lacustrine sediments.

  • 73. WILLIAMS, CHRISTOPHER N.
    et al.
    CARRIVICK, JONATHAN L.
    EVANS, ANDREW J.
    RIPPIN, DAVID M.
    QUANTIFYING UNCERTAINTY IN USING MULTIPLE DATASETS TO DETERMINE SPATIOTEMPORAL ICE MASS LOSS OVER 101 YEARS AT KÅRSAGLACIÄREN, SUB2016In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 98, no 1, p. 61-79Article in journal (Refereed)
    Abstract [en]

    Glacier mass balance and mass balance gradient are fundamentally affected by changes in glacier 3D geometry. Few studies have quantified changing mountain glacier 3D geometry, not least because of a dearth of suitable spatiotemporally distributed topographical information. Additionally, there can be significant uncertainty in georeferencing of historical data and subsequent calculations of the difference between successive surveys. This study presents multiple 3D glacier reconstructions and the associated mass balance response of Kårsaglaciären, which is a 0.89 ± 0.01 km2 mountain glacier in sub

  • 74. Yang, Zhenlin
    et al.
    Hanna, Edward
    Callaghan, Terry V.
    Modelling surface‐air‐temperature variation over complex terrain around abisko, swedish lapland: uncertainties of measurements and models at different scales2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Geografiska Annaler: Series A, Physical Geography, Vol. 93, no 2, p. 89-112Article in journal (Refereed)
    Abstract [en]

    Many ecological, physical and geographical processes affected by climate in the natural environment are scale‐dependent: determining surface‐air‐temperature distribution at a scale of tens to hundreds of metres can facilitate such research, which is currently hampered by the relative dearth of meteorological stations and complex surface temperature characteristics, particularly in mountain areas. Here we discuss both the couplings and mismatch of present climatological data at different scales, ranging from ∼50 m to 100 km, and provide a novel model of the surface‐air‐temperature distribution in topographically heterogeneous regions.

    First, a comparison of the large‐scale weather station measurements and gridded climate reanalysis (ERA‐40) data is used to define regional climatology in the Swedish sub‐Arctic and obtain the mesoscale temperature lapse rates. Second, combined with temperature measurements obtained from transects set among complex terrain, key microclimatic characteristics of the temperature distribution are identified, showing few temperature inversions when the wind speed exceeds 3 m s−1, while temperature inversions prevail during calm nights. Besides wind, there is a pronounced winter temperature stratification around the large Lake Torneträsk, and variations in topography are found to have a strong influence in shaping the microscale temperature pattern through their effect on solar radiation during summer.

    A monthly 50‐m scale temperature‐distribution (topoclimate) model is built based on the above findings, and model validation is conducted using further fieldwork measurements from different seasons. We present results of surface‐air‐temperature distribution for the Abisko region, and discuss how these results help reconcile the scale mismatch mentioned above.

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