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  • Resultat 1-10 av 47
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1.
  • Pihl, Håkan, 1960-, et al. (författare)
  • Is coordination influenced by culture? : a comparison of Sweden and China
  • 2010
  • Ingår i: Problems and Perspectives in Management. - 1727-7051. ; 8:1, s. 61-69
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of this paper is to analyse cultural influences on the choice of coordination mechanisms. Based on the Globe report, propositions are developed on how different cultural dimensions affect the choice of coordination mechanisms. Market mechanisms are proposed to be preferred in cultures characterized by a high level of performance orientation, assertiveness, in-group collectivism and low levels of institutional collectivism, power distance and uncertainty avoidance. Societies with the opposite profile are expected to have a bias in favour of hierarchical mechanisms. Based on the propositions, the cultural clusters identified in the Globe report are analysed and categorized according to their relative preferences for market or hierarchical mechanisms. Finally, an experimental study was performed to study cultural biases in choice of coordination mechanisms. In the experiment, two groups of students of Swedish and Chinese origin performed roles as principals and agents in a multi-task situation. According to the previous analysis Swedish students were expected to show a strong preference for hierarchal mechanisms whereas Chinese students were expected to have preference for market mechanisms. The result supported these predictions.
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2.
  • Aldenhoff, Wiebke, 1985, et al. (författare)
  • Comparison of ice/water classification in Fram Strait from C- and L-band SAR imagery
  • 2018
  • Ingår i: Annals of Glaciology. - : Cambridge University Press (CUP). - 0260-3055 .- 1727-5644. ; 59:76pt2, s. 112-123
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper an algorithm for ice/water classification of C- and L-band dual polarization synthetic aperture radar data is presented. A comparison of the two different frequencies is made in order to investigate the potential to improve classification results with multi-frequency data. The algorithm is based on backscatter intensities in co- and cross-polarization and autocorrelation as a texture feature. The mapping between image features and ice/water classification is made with a neural network. Accurate ice/water maps for both frequencies are produced by the algorithm and the results of two frequencies generally agree very well. Differences are found in the marginal ice zone, where the time difference between acquisitions causes motion of the ice pack. C-band reliably reproduces the outline of the ice edge, while L-band has its strengths for thin ice/calm water areas within the icepack. The classification shows good agreement with ice/water maps derived from met.no ice-charts and radiometer data from AMSR-2. Variations are found in the marginal ice zone where the generalization of the ice charts and lower accuracy of ice concentration from radiometer data introduce deviations. Usage of high-resolution dual frequency data could be beneficial for improving ice cover information for navigation and modelling.
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3.
  • Arendt, Anthony A., et al. (författare)
  • Glacier changes in Alaska : can mass-balance models explain GRACE mascon trends?
  • 2009
  • Ingår i: Annals of Glaciology. - 0260-3055 .- 1727-5644. ; 50:50, s. 148-154
  • Tidskriftsartikel (refereegranskat)abstract
    • Temperature and precipitation data from three weather stations in the St Elias Mountains of Alaska and northwestern Canada were used to drive one-dimensional (1-D) (elevation-dependent) and 0-D degree-day mass-balance models. Model outputs were optimized against a 10 day resolution time series of mass variability during 2003-07 obtained from Gravity Recovery and Climate Experiment (GRACE) mass concentration (mascon) solutions. The models explained 52-60% of the variance in the GRACE time series. Modelled mass variations matched the phase of the GRACE observations, and all optimized model parameters were within the range of values determined from conventional mass-balance and meteorological observations. We describe a framework for selecting appropriate weather stations and mass-balance models to represent glacier variations of large regions. There is potential for extending these calibrated mass-balance models forwards or backwards in time to construct mass-balance time series outside of the GRACE measurement window.
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6.
  • Bliss, Andrew, et al. (författare)
  • A new inventory of mountain glaciers and ice caps for the Antarctic periphery
  • 2013
  • Ingår i: Annals of Glaciology. - 0260-3055 .- 1727-5644. ; 54:63, s. 191-199
  • Tidskriftsartikel (refereegranskat)abstract
    • Although the glaciers in the Antarctic periphery make up a large fraction of all mountain glaciers and ice caps on Earth, a detailed glacier inventory of the region is lacking. We compile such an inventory, recording areas, area-altitude distributions, terminus characteristics and volume estimates. Glaciers on the mainland are excluded. The inventory is derived from the Antarctic Digital Database and some manual digitization. We additionally rely on satellite imagery, digital elevation models and a flowshed algorithm to classify ice bodies. We find 1133 ice caps and 1619 mountain glaciers covering a total of 132 867 +/- 6643 km(2). Estimated total volume corresponds to 0.121 +/- 0.010 m sea-level equivalent. Of the total glacier area, 99% drains either into ice shelves (63%) or into the ocean (36%). The inventory will provide a database for glacier mass-balance assessments, modelling and projections, and help to reduce the uncertainties in previous studies.
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7.
  • Booth, Adam D., et al. (författare)
  • A comparison of seismic and radar methods to establish the thickness and density of glacier snow cover
  • 2013
  • Ingår i: Annals of Glaciology. - 0260-3055 .- 1727-5644. ; 54:64, s. 73-82
  • Tidskriftsartikel (refereegranskat)abstract
    • We show that geophysical methods offer an effective means of quantifying snow thickness and density. Opportunistic (efficient but non-optimized) seismic refraction and ground-penetrating radar (GPR) surveys were performed on Storglaciaren, Sweden, co-located with a snow pit that shows the snowpack to be 1.73 m thick, with density increasing from similar to 120 to similar to 500 kg m(-3) (with a +50 kg m(-3) anomaly between 0.73 and 0.83 m depth). Depths estimated for two detectable GPR reflectors, 0.76 +/- 0.02 and 1.71 +/- 0.03 m, correlate extremely well with ground-truth observations. Refraction seismic predicts an interface at 1.90 +/- 0.31 m depth, with a refraction velocity (3730 +/- 190 m s(-1)) indicative of underlying glacier ice. For density estimates, several standard velocity-density relationships are trialled. In the best case, GPR delivers an excellent density estimate for the upper snow layer (observed = 321 +/- 74 kg m(-3), estimated = 319 +/- 10 kg m(-3)) but overestimates the density of the lower layer by 20%. Refraction seismic delivers a bulk density of 404 +/- 22 kg m(-3) compared with a ground-truth average of 356 +/- 22 kg m(-3). We suggest that geophysical surveys are an effective complement to mass-balance measurements (particularly for controlling estimates of snow thickness between pits) but should always be validated against ground-truth observations.
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8.
  • Butcher, Frances E.G., et al. (författare)
  • Eskers associated with buried glaciers in Mars' mid latitudes: recent advances and future directions
  • 2022
  • Ingår i: Annals of Glaciology. - : Cambridge University Press. - 0260-3055 .- 1727-5644. ; 63:87-89, s. 33-38
  • Tidskriftsartikel (refereegranskat)abstract
    • Until recently, the influence of basal liquid water on the evolution of buried glaciers in Mars' mid latitudes was assumed to be negligible because the latter stages of Mars' Amazonian period (3 Ga to present) have long been thought to have been similarly cold and dry to today. Recent identifications of several landforms interpreted as eskers associated with these young (100s Ma) glaciers calls this assumption into doubt. They indicate basal melting (at least locally and transiently) of their parent glaciers. Although rare, they demonstrate a more complex mid-to-late Amazonian environment than was previously understood. Here, we discuss several open questions posed by the existence of glacier-linked eskers on Mars, including on their global-scale abundance and distribution, the drivers and dynamics of melting and drainage, and the fate of meltwater upon reaching the ice margin. Such questions provide rich opportunities for collaboration between the Mars and Earth cryosphere research communities.
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9.
  • Charalampidis, Charalampos, 1983-, et al. (författare)
  • Thermal tracing of retained meltwater in the lower accumulation area of the Southwestern Greenland ice sheet
  • 2016
  • Ingår i: Annals of Glaciology. - : International Glaciological Society. - 0260-3055 .- 1727-5644. ; 57:72, s. 1-10
  • Tidskriftsartikel (refereegranskat)abstract
    • We present in situ firn temperatures from the extreme 2012 melt season in the southwestern lower accumulation area of the Greenland ice sheet. The upper 2.5 m of snow and firn was temperate during the melt season, when vertical meltwater percolation was inefficient due to a c. 5.5 m thick ice layer underlying the temperate firn. Meltwater percolation and refreezing beneath 2.5 m depth only occurred after the melt season. Deviations from temperatures predicted by pure conductivity suggest that meltwater refroze in discrete bands at depths of 2.0–2.5, 5.0–6.0 and 8.0–9.0 m. While we find no indication of meltwater percolation below 9 m depth or complete filling of pore volume above, firn at 10 and 15 m depth was respectively 4.2–4.5 degrees C and 1.7 degrees C higher than in a conductivity-only simulation. Even though meltwater percolation in 2012 was inefficient, firn between 2 and 15 m depth the following winter was on average 4.7 degrees C warmer due to meltwater refreezing. Our observations also suggest that the 2012 firn conditions were preconditioned by two warm summers and ice layer formation in 2010 and 2011. Overall, firn temperatures during the years 2009–13 increased by 0.6 degrees C.
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10.
  • Dahlke, Helen E., et al. (författare)
  • Early melt season snowpack isotopic evolution in the Tarfala valley, northern Sweden
  • 2013
  • Ingår i: Annals of Glaciology. - 0260-3055 .- 1727-5644. ; 54:62, s. 149-156
  • Tidskriftsartikel (refereegranskat)abstract
    • This study investigated the stable water isotopic (delta O-18 and delta D) evolution of two snowpacks located at the same elevation on a north-facing (Nf) and a south-facing (Sf) slope within the Tarfala research catchment, northern Sweden, and the potential impact of pre-freshet snowpack melt on streamflow. Our results indicate that over the study period the Sf snowpack showed a more enriched isotopic composition, especially in the top of the profile, and contributed more snowmelt to streamflow than the Nf slope. The Sf snowpack also showed a significantly higher variability in snowpack delta O-18 levels and snowpack snow water equivalent (SWE) over time. Comparing snowpack and snowmelt isotopic values it was seen that the Sf slope experienced earlier snowmelt from upslope positions due to greater insolation that subsequently enhanced the meltwater flux at the base of downslope snowpacks. In contrast, the Nf slope primarily underwent changes within the snowpack and experienced relatively minimal melt. Detailed field-based isotopic snowmelt studies such as this highlight the potential importance of incorporating spatio-temporal runoff generation concepts into distributed energy-balance models, which could allow for more accurate prediction with regard to the spatio-temporal dynamics associated with the snowmelt ion pulse.
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