Journal: Annals of Glaciology

Abbreviation

Ann Glaciol

Publisher

International Glaciological Society

Journal Volumes

ISSN

0260-3055
1727-5644

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Publications1 - 10 of 75
  • Evolution of Rhonegletscher, Switzerland, over the past 125 years and in the future: application of an improved flowline model
    Item type: Conference Paper
    Sugiyama, Shin; Bauder, Andreas; Zahno, Conradin; et al. (2007)
    Annals of Glaciology ~ Papers from the International Symposium on Cryospheric Indicators of Global Climate Change: held in Cambridge, UK, on 21-25 August, 2006
    To study the past and future evolution of Rhonegletscher, Switzerland, a flowline model was developed to include valley shape effects more accurately than conventional flowband models. In the model, the ice flux at a gridpoint was computed by a two-dimensional ice-flow model applied to the valley cross-section. The results suggested the underestimation of the accumulation area, which seems to be a general problem of flowline modelling arising from the model’s one-dimensional nature. The corrected mass balance was coupled with the equilibrium-line altitude (ELA) change, which was reconstructed for the period 1878–2003 from temperature and precipitation records, to run the model for the past 125 years. The model satisfactorily reproduced both changes in the terminus position and the total ice volume derived from digital elevation models of the surface obtained by analyses of old maps and aerial photographs. This showed the model’s potential to simulate glacier evolution when an accurate mass balance could be determined. The future evolution of Rhonegletscher was evaluated with three mass-balance conditions: the mean for the period 1994–2003, and the most negative (2003) and positive (1978) mass-balance values for the past 50 years. The model predicted volume changes of –18%, –58% and +38% after 50 years for the three conditions, respectively.
  • Mass-balance estimates for Haut Glacier d'Arolla, Switzerland, from 2000 to 2006 using DEMs and distributed mass-balance modeling
    Item type: Conference Paper
    Dadić, Ružica; Corripio, Javier G.; Burlando, Paolo (2008)
    Annals of Glaciology ~ Selected Papers from the International Symposium on Snow Science: Held in the City of Moscow, Russia, 3-7 September, 2007
  • On the role of subsurface heat conduction in glacier energy-balance modelling
    Item type: Journal Article
    Pellicciotti, Francesca; Carenzo, Marco; Helbing, Jakob; et al. (2009)
    Annals of Glaciology
  • Ice-volume changes of selected glaciers in the Swiss Alps since the end of the 19th century
    Item type: Conference Paper
    Bauder, Andreas; Funk, Martin; Huss, Matthias (2007)
    Annals of Glaciology ~ Papers from the International Symposium on Cryospheric Indicators of Global Climate Change: Held in the City of Cambridge, England, 21-25 August, 2006
    The evolution of surface topography of glaciers in the Swiss Alps is well documented with high-resolution aerial photographs repeatedly recorded since the 1960s and further back in time with topographic maps including elevation contour lines first surveyed in the mid-19th century. In order to quantify and interpret glacier changes in the Swiss Alps, time series of volume changes over the last 100–150 years have been collected. The available datasets provide a detailed spatial resolution for the retreat period since the end of the Little Ice Age. The spatial distribution as well as temporal variations of the thickness change were analyzed. A significant ice loss since the end of the 19th century was observed in the ablation area, while the changes in the accumulation area were small. We found moderate negative secular rates until the 1960s, followed by steady to positive rates for about two decades and strong ice loss starting in the 1980s which has lasted until the present. An evaluation of 19 glaciers revealed a total ice volume loss of about 13km3 since the 1870s, of which 8.7 km3 occurred since the 1920s and 3.5 km3 since 1980. Decadal mean net balance rates for the periods 1920–60, 1960–80 and 1980–present are –0.29, –0.03 and –0.53ma–1w.e., respectively.
  • Simulating the effect of mean annual air-temperature changes on permafrost distribution and glacier size: An Example from the Upper Engadin, Swiss Alps
    Item type: Journal Article
    Hoelzle, Martin; Haeberli, Wilfried (1995)
    Annals of Glaciology
    Models are developed to simulate changes in permafrost distribution and glacier size in mountain areas. The models exclusively consider equilibrium conditions. As a first application, the simplified assumption is used that one single parameter (mean annual air temperature) is changing. Permafrost distribution patterns are estimated for a test area (Corvatsch-Furtschellas) and for the whole Upper Engadin region (eastern Swiss Alps) using a relation between permafrost occurrence as indicated by BTS (bottom temperature of the winter snow cover) measurements, potential direct solar radiation and mean annual air temperature. Glacier sizes were assessed in the same region with data from the World Glacier Inventory database. The simulations for the glaciers are based on the assumption that an increase or decrease in equilibrium-line altitude (ELA) would lead to a mass-balance change. Model calculations for potential future changes in ELA and mass balance include estimated developments of area, length and volume. Mass changes were also calculated for the time period 1850–1973 on the basis of measured cumulative length change, glacier length and estimated ablation at the glacier terminus. For the time period since 1850, permafrost became inactive or disappeared in about 15% of the area originally underlain by permafrost in the whole Upper Engadin region, and mean annual glacier mass balance was calculated as −0.26 to −0.46 m w.e.a−1 for the larger glaciers in the same area. The estimated loss in glacier volume since 1850 lies between 55% and 66% of the original value. With an assumed increase in mean annual air temperature of +3°C, the area of supposed permafrost occurrence would possibly be reduced by about 65% with respect to present-day conditions and only three glaciers would continue to partially exist.
  • Variability of air temperature over a debris-covered glacier in the Nepalese Himalaya
    Item type: Journal Article
    Steiner, Jakob F.; Pellicciotti, Francesca (2016)
    Annals of Glaciology
    Estimates of melt from debris-covered glaciers require distributed estimates of meteorological variables and air temperature in particular. Meteorological data are scarce for this environment, and spatial variability of temperature over debris is poorly understood. Based on multiple measurements of air and surface temperature from three ablation seasons (2012–14) we investigate the variability of temperature over Lirung Glacier, Nepal, in order to reveal how air temperature is affected by the debris cover and improve ways to extrapolate it. We investigate how much on-glacier temperature deviates from that predicted from a valley lapse rate (LR), analyse on-glacier LRs and test regression models of air temperature and surface temperature. Air temperature over the debris-covered glacier tongue is much higher than what a valley LR would prescribe, so an extrapolation from off-glacier stations is not applicable. An on-glacier LR is clearly defined at night, with strong correlation, but not during the day, when the warming debris disrupts the elevation control. An alternative to derive daytime air temperature is to use a relationship between air and surface temperature, as previously suggested. We find strong variability during daytime that should be accounted for if these regressions are used for temperature extrapolation.
  • The signal from the Chernobyl accident in high-altitude firn areas of the Swiss Alps
    Item type: Journal Article
    Haeberli, Wilfried; Gäggeler, Heinz; Baltensperger, Urs; et al. (1988)
    Annals of Glaciology
    In order to investigate the deposition of radioactive fission nuclides in the high-altitude snow and firn of the Swiss Alps after the Chernobyl accident, core samples from nine mountain peaks were analyzed. The observed radiological signal is described, together with the characteristics of the snow in which it is embedded. Total activity is of the same order of magnitude (around 10 kBq/m2) as deposition rates measured at lower altitudes, and shows a comparable regional distribution. A clear altitudinal trend only exists with respect to snow conditions: above about 4000 m a.s.l., erosion, mixing and resedimentation of cold snow by wind could have occurred during or shortly after the deposition, whereas at lower altitudes formation and percolation of melt water had already started — probably selectively — to redistribute the nuclides within temperate firn layers.
  • The bedrock topography of Starbuck Glacier, Antarctic Peninsula, as determined by radio-echo soundings and flow modeling
    Item type: Journal Article
    Farinotti, Daniel; King, Edward C.; Albrecht, Anika; et al. (2014)
    Annals of Glaciology
    A glacier-wide ice-thickness distribution and bedrock topography is presented for Starbuck Glacier, Antarctic Peninsula. The results are based on 90 km of ground-based radio-echo sounding lines collected during the 2012/13 field season. Cross-validation with ice-thickness measurements provided by NASA's IceBridge project reveals excellent agreement. Glacier-wide estimates are derived using a model that calculates distributed ice thickness, calibrated with the radio-echo soundings. Additional constraints are obtained from in situ ice flow-speed measurements and the surface topography. The results indicate a reverse-sloped bed extending from a riegel occurring ~ 5 km upstream of the current grounding line. The deepest parts of the glacier are as much as 500 m below sea level. The calculated total volume of 80.7 ± 7.2 km3 corresponds to an average ice thickness of 312 ± 30 m.
  • An improved numerical scheme to compute horizontal gradients at the ice-sheet margin: its effect on the simulated ice thickness and temperature
    Item type: Conference Paper
    Saito, Fuyuki; Abe-Ouchi, Ayako; Blatter, Heinz (2007)
    Annals of Glaciology ~ Papers from the International Symposium on Cryospheric Indicators of Global Climate Change: held in Cambridge, UK, on 21-25 August, 2006
    In three-dimensional numerical ice-sheet models that use finite-difference schemes, the position of ice margins is poorly represented with a regular quadratic grid. As a result, in a centered difference scheme, the surface gradient term and the flux divergence term computed for the gridpoints next to the ice margin may be inaccurate. In this paper, an improved scheme is presented that computes the horizontal gradients at the ice-sheet margin using an asymmetric (upstream) second-order difference scheme in order to avoid using information from the zero-thickness gridpoints. The model is applied to an idealized synthetic geometry to obtain a steady-state ice-sheet topography. The improved model shows a realistically smooth thickness distribution near the margin. Thermomechanical coupling is found to enhance the error near the margin. The error in simulated thicknesses with the centered-difference method was significantly reduced with the new upstream scheme.
  • Glacier and permafrost signals of 20th Century warming
    Item type: Journal Article
    Haeberli, Wilfried (1990)
    Annals of Glaciology
    Currently-available evidence of 20th-century warming from glaciers and permafrost is briefly reviewed. The signals are clear and strong: warming of polar firn and permafrost, and mass losses of glaciers at lower latitudes, were most striking towards the middle of the century. The easily observable length-reduction of mountain glaciers confirms the global character of the evolution. A probably intermittent reversal of the trend was observed in places after about 1950.
Publications1 - 10 of 75