scholarly journals Using surface velocities to calculate ice thickness and bed topography: a case study at Columbia Glacier, Alaska, USA

2012 ◽  
Vol 58 (212) ◽  
pp. 1151-1164 ◽  
Author(s):  
R.W. Mcnabb ◽  
R. Hock ◽  
S. O’Neel ◽  
L.A. Rasmussen ◽  
Y. Ahn ◽  
...  
Keyword(s):  
Thickness Distribution ◽  
Computational Time ◽  
Ice Thickness ◽  
Thickness Change ◽  
Bed Topography ◽  
Surface Data ◽  
Direct Measurements ◽  
The Mean ◽  
Time Required

AbstractInformation about glacier volume and ice thickness distribution is essential for many glaciological applications, but direct measurements of ice thickness can be difficult and costly. We present a new method that calculates ice thickness via an estimate of ice flux. We solve the familiar continuity equation between adjacent flowlines, which decreases the computational time required compared to a solution on the whole grid. We test the method on Columbia Glacier, a large tidewater glacier in Alaska, USA, and compare calculated and measured ice thicknesses, with favorable results. This shows the potential of this method for estimating ice thickness distribution of glaciers for which only surface data are available. We find that both the mean thickness and volume of Columbia Glacier were approximately halved over the period 1957–2007, from 281 m to 143 m, and from 294 km3 to 134 km3, respectively. Using bedrock slope and considering how waves of thickness change propagate through the glacier, we conduct a brief analysis of the instability of Columbia Glacier, which leads us to conclude that the rapid portion of the retreat may be nearing an end.

scholarly journals A method to estimate the ice volume and ice-thickness distribution of alpine glaciers

2009 ◽  
Vol 55 (191) ◽  
pp. 422-430 ◽  
Author(s):  
Daniel Farinotti ◽  
Matthias Huss ◽  
Andreas Bauder ◽  
Martin Funk ◽  
Martin Truffer
Keyword(s):  
Mass Balance ◽  
Thickness Distribution ◽  
Ice Thickness ◽  
Average Deviation ◽  
Glacier Surface ◽  
Ice Flow ◽  
Thickness Change ◽  
Ice Volume ◽  
Alpine Glaciers ◽  
Direct Measurements

AbstractSound knowledge of the ice volume and ice-thickness distribution of a glacier is essential for many glaciological applications. However, direct measurements of ice thickness are laborious, not feasible everywhere and necessarily restricted to a small number of glaciers. In this paper, we present a method to estimate the ice-thickness distribution and the total ice volume of alpine glaciers. This method is based on glacier mass turnover and principles of ice-flow mechanics. The required input data are the glacier surface topography, the glacier outline and a set of borders delineating different ‘ice-flow catchments’. Three parameters describe the distribution of the ‘apparent mass balance’, which is defined as the difference between the glacier surface mass balance and the rate of ice-thickness change, and two parameters define the ice-flow dynamics. The method was developed and validated on four alpine glaciers located in Switzerland, for which the bedrock topography is partially known from radio-echo soundings. The ice thickness along 82 cross-profiles can be reproduced with an average deviation of about 25% between the calculated and the measured ice thickness. The cross-sectional areas differ by less than 20% on average. This shows the potential of the method for estimating the ice-thickness distribution of alpine glaciers without the use of direct measurements.

scholarly journals Ice thickness distribution of all Swiss glaciers based on extended ground-penetrating radar data and glaciological modeling

2021 ◽  
pp. 1-19
Author(s):  
Melchior Grab ◽  
Enrico Mattea ◽  
Andreas Bauder ◽  
Matthias Huss ◽  
Lasse Rabenstein ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Thickness Distribution ◽  
Radar Data ◽  
Tourism Industry ◽  
Swiss Alps ◽  
Ice Thickness ◽  
Hazard Management ◽  
Bed Topography ◽  
Ice Volume ◽  
Ground Penetrating

Abstract Accurate knowledge of the ice thickness distribution and glacier bed topography is essential for predicting dynamic glacier changes and the future developments of downstream hydrology, which are impacting the energy sector, tourism industry and natural hazard management. Using AIR-ETH, a new helicopter-borne ground-penetrating radar (GPR) platform, we measured the ice thickness of all large and most medium-sized glaciers in the Swiss Alps during the years 2016–20. Most of these had either never or only partially been surveyed before. With this new dataset, 251 glaciers – making up 81% of the glacierized area – are now covered by GPR surveys. For obtaining a comprehensive estimate of the overall glacier ice volume, ice thickness distribution and glacier bed topography, we combined this large amount of data with two independent modeling algorithms. This resulted in new maps of the glacier bed topography with unprecedented accuracy. The total glacier volume in the Swiss Alps was determined to be 58.7 ± 2.5 km3 in the year 2016. By projecting these results based on mass-balance data, we estimated a total ice volume of 52.9 ± 2.7 km3 for the year 2020. Data and modeling results are accessible in the form of the SwissGlacierThickness-R2020 data package.

scholarly journals Quiescent-phase evolution of a surge-type glacier: Black Rapids Glacier, Alaska, U.S.A.

1996 ◽  
Vol 42 (140) ◽  
pp. 110-122 ◽  
Author(s):  
T.A. Heinrichs ◽  
L.R. Mayo ◽  
K.A. Echelmeyer ◽  
W.D. Harrison
Keyword(s):  
Phase Evolution ◽  
Ice Thickness ◽  
Alaska Range ◽  
Thickness Change ◽  
Quiescent Phase ◽  
Cyclical Fluctuations ◽  
Ice Velocity ◽  
The Mean ◽  
Black Rapids Glacier ◽  
Speed Fluctuations

AbstractBlack Rapids Glacier, a surge-type glacier in the Alaska Range, most recently surged in 1936–37 and is currently in its quiescent phase. Mass balance, ice velocity and thickness change have been measured at three to ten sites from 1972 to 1994. The annual speed has undergone cyclical fluctuations of as much as 45% about the mean speed. Ice thickness and surface slope did not change enough to cause the speed fluctuations through changes in ice deformation, which indicates that they are being drinven by changes in basal motion. The behavior of Black Rapids Glacier during this quiescent phase is significantly different from that of Variegated Glacier, another well-studied surge-type glacier in Alaska. The present medial-moraine configuration of Black Rapids Glacier indicates that a surge could occur at any time. However, ice velocity data indicate that the next surge may not be imminent. We belive that there is little chance that the next surge will cross and dam the Delta River.

scholarly journals Seasonal development of the sea-ice thickness distribution in East Antarctica: measurements from upward-looking sonar

2001 ◽  
Vol 33 ◽  
pp. 177-180 ◽  
Author(s):  
A. P. Worby ◽  
G. M. Bush ◽  
I. Allison
Keyword(s):  
Sea Ice ◽  
Thickness Distribution ◽  
East Antarctica ◽  
Seasonal Development ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Seasonal Evolution ◽  
Pack Ice ◽  
The Mean ◽  
Prototype Instrument

AbstractUpward-looking sonar (ULS) data are presented from a prototype instrument deployed at 63° 18’ S, 107°49’ E in 1994. These data show the seasonal evolution of the ice-draft distribution from May when predominantly thin ice is present, through October when substantially thicker ice has been formed by deformation. The mean ice draft reaches a maximum in August at 1.21 m, the same month in which ship-based observations from the same region show a peak in ice thickness. The observed distribution from ULS data is only for drafts > 0.3 m due to data losses caused by the low acoustic reflectivity of actively forming ice. The spring distributions show very little development of drafts > 3.0 m, and it is hypothesized that this is due to the cyclical nature of deformation in the East Antarctic pack-ice zone, and that periods of sustained pressure required to form very thick ice are uncommon in this region

scholarly journals Quiescent-phase evolution of a surge-type glacier: Black Rapids Glacier, Alaska, U.S.A.

1996 ◽  
Vol 42 (140) ◽  
pp. 110-122 ◽  
Author(s):  
T.A. Heinrichs ◽  
L.R. Mayo ◽  
K.A. Echelmeyer ◽  
W.D. Harrison
Keyword(s):  
Phase Evolution ◽  
Ice Thickness ◽  
Alaska Range ◽  
Thickness Change ◽  
Quiescent Phase ◽  
Cyclical Fluctuations ◽  
Ice Velocity ◽  
The Mean ◽  
Black Rapids Glacier ◽  
Speed Fluctuations

AbstractBlack Rapids Glacier, a surge-type glacier in the Alaska Range, most recently surged in 1936–37 and is currently in its quiescent phase. Mass balance, ice velocity and thickness change have been measured at three to ten sites from 1972 to 1994. The annual speed has undergone cyclical fluctuations of as much as 45% about the mean speed. Ice thickness and surface slope did not change enough to cause the speed fluctuations through changes in ice deformation, which indicates that they are being drinven by changes in basal motion. The behavior of Black Rapids Glacier during this quiescent phase is significantly different from that of Variegated Glacier, another well-studied surge-type glacier in Alaska. The present medial-moraine configuration of Black Rapids Glacier indicates that a surge could occur at any time. However, ice velocity data indicate that the next surge may not be imminent. We belive that there is little chance that the next surge will cross and dam the Delta River.

scholarly journals Ice ridging and ice drift in Southern Gulf of St Lawrence, Canada, during winter Storms

2006 ◽  
Vol 44 ◽  
pp. 411-417 ◽  
Author(s):  
S.J. Prinsenberg ◽  
A. Van Der Baaren ◽  
I.K. Peterson
Keyword(s):  
Prince Edward Island ◽  
Thickness Distribution ◽  
Ice Thickness ◽  
Winter Storms ◽  
The North ◽  
Pack Ice ◽  
Ice Drift ◽  
The Mean ◽  
Ice Floes ◽  
Drift Conditions

AbstractDuring February and March 2004, Satellite-tracked ice beacons and helicopter-borne Sensors collected ice-drift and ice-thickness data from the Southern Gulf of St Lawrence, Canada, to Study the region’s ice-thickness evolution and ice-drift behavior in response to winter Storms. Three northeasterly Storms passed through the area during the observation period, pushing the pack ice against the north Shore of Prince Edward Island. The resulting Severe ice deformation caused major changes in the ice-thickness distribution of two pack-ice areas tracked by ice beacons that Survived the Storms. The ice drift ranged from 1.4% to 2.9% of the wind Speed during free ice-drift conditions, decreasing to 0% when the pack ice compacted against the Shoreline. Most of the thinner ice deformed first, increasing the mean ice thickness over 6–8 km line Sections around the beacons from 0.6 and 0.3 m before the Storms to 1.9 and 2.0 m after the Storms. The ice-thickness increases can be accounted for by the reduced pack-ice area due to ice ridging. Over the next 4weeks, deformation continued and the mean ice thickness around the beacons increased to 2.8 m, well in excess of the maximum undeformed possible ice growth of 65 cm. Ice charts captured the ice thickness of undeformed and composite ice floes but did not capture the ice volume in ice-rubble fields.

A study of a rover wheel for Martian explorations, based on a flexible multibody approach

2019 ◽  
Vol 234 (2) ◽  
pp. 306-321 ◽  
Author(s):  
Stefano Sivo ◽  
Angelo Stio ◽  
Francesco Mocera ◽  
Aurelio Somà
Keyword(s):  
Ad Hoc ◽  
General Purpose ◽  
Design Stage ◽  
Computational Time ◽  
Multibody Model ◽  
Modelling Strategies ◽  
Pros And Cons ◽  
Time Required ◽  
Solution Accuracy

Vehicles for planetary exploration have to operate in completely different environments from Earth. For this reason, the design process of the exploration unit has an important role and can affect the requirements of the entire mission for the different space agencies involved. These operations are very expensive and time consuming, so that, over the years, ad hoc CAE methods have been developed to help engineers in the design stage. These methods are used to simulate several working conditions, evaluating which manoeuvres robots can safely perform during their mission. In this framework, a study was performed by Politecnico di Torino and Thales Alenia Space Italia. The goal was to find an efficient way to implement flexibility properties of a special wheel of a Rover for Martian explorations in a commercial (general purpose) MTB code. The ExoMars Rover was considered as case study of this work. When dealing with manoeuvres feasibility analysis, the best compromise between solution accuracy and computational time required must be found. The aim of this study was to explore pros and cons of several techniques which could allow modelling a complex flexible wheel using a commercial general-purpose MTB code. The absolute nodal coordinate formulation was compared with the other reduced-order modelling strategies proposed by the authors to implement the flexibility of a wheel in a multibody model of the full vehicle. Numerical results show good performance of the reduced morphing model in terms of computational time versus numerical accuracy.

scholarly journals Ice thickness, areal and volumetric changes of Davies Dome and Whisky Glacier (James Ross Island, Antarctic Peninsula) in 1979–2006

2012 ◽  
Vol 58 (211) ◽  
pp. 904-914 ◽  
Author(s):  
Zbynĕk Engel ◽  
Daniel Nývlt ◽  
Kamil Láska
Keyword(s):  
Antarctic Peninsula ◽  
Ground Penetrating Radar ◽  
Ice Thickness ◽  
Bed Topography ◽  
Ice Cap ◽  
Valley Glacier ◽  
Elevation Changes ◽  
James Ross Island ◽  
The Mean ◽  
Ground Penetrating

AbstractThis study calculates area, volume and elevation changes of two glaciers on James Ross Island, Antarctica, during the period 1979-2006. Davies Dome is a small ice cap. Whisky Glacier is a valley glacier. Ground-penetrating radar surveys indicate ice thickness, which was used for calculations of the bed topography and volume of both glaciers. Maximum measured ice thicknesses of Davies Dome and Whisky Glacier are 83 ± 2 and 157 ± 2 m, respectively. Between 1979 and 2006, the area of the ice cap decreased from 6.23 ± 0.05 km2 to 4.94 ± 0.01 km2 (-20.7%), while the area of the valley glacier reduced from 2.69 ± 0.02 km2 to 2.40 ± 0.01 km2 (-10.6%). Over the same period the volume of the ice cap and valley glacier reduced from 0.23 ± 0.03 km3 to 0.16 ± 0.02 km3 (-30.4%) and from 0.27 ± 0.02 km3 to 0.24 ± 0.01 km3 (-10.6%), respectively. The mean surface elevation decreased by 8.5±2.8 and 10.1 ±2.8m. The average areal (~0.048-0.011 km2a-1) and volumetric (~0.003−0.001 km3 a-1) changes are higher than the majority of other estimates from Antarctic Peninsula glaciers.

scholarly journals A Practical Formulation for Ex-Ante Scheduling of Energy and Reserve in Renewable-Dominated Power Systems: Case Study of the Iberian Peninsula

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1939 ◽  
Author(s):  
Miguel Carrión ◽  
Rafael Zárate-Miñano ◽  
Ruth Domínguez
Keyword(s):  
Stochastic Programming ◽  
Power Systems ◽  
Power System ◽  
Iberian Peninsula ◽  
Ad Hoc ◽  
Computational Time ◽  
Operational Practices ◽  
Mathematical Programming Problems ◽  
Time Required

Scheduling energy and reserve in power systems with a large number of intermittent units is a challenging problem. Traditionally, the reserve requirements are assigned after clearing the day-ahead energy market using ad hoc rules or solving computationally intense mathematical programming problems to co-optimize energy and reserve. While the former approach often leads to costly oversized reserve provisions, the computational time required by the latter makes it generally incompatible with the daily power system operational practices. This paper proposes an alternative deterministic formulation for computing the energy and reserve scheduling, considering the uncertainty of the demand and the intermittent power production in such a way that the resulting problem requires a lower number of constraints and variables than stochastic programming-based formulations. The performance of the proposed formulation has been compared with respect to two standard stochastic programming formulations in a small-size power system. Finally, a realistic case study based on the Iberian Peninsula power system has been solved and discussed.

scholarly journals Results from the Ice Thickness Models Intercomparison eXperiment Phase 2 (ITMIX2)

2021 ◽  
Vol 8 ◽  
Author(s):  
Daniel Farinotti ◽  
Douglas J. Brinkerhoff ◽  
Johannes J. Fürst ◽  
Prateek Gantayat ◽  
Fabien Gillet-Chaulet ◽  
...  
Keyword(s):  
Spatial Information ◽  
Numerical Models ◽  
Spatial Scales ◽  
Thickness Distribution ◽  
Data Availability ◽  
Added Value ◽  
Ice Thickness ◽  
Test Case ◽  
Glacier Surface ◽  
The Mean

Knowing the ice thickness distribution of a glacier is of fundamental importance for a number of applications, ranging from the planning of glaciological fieldwork to the assessments of future sea-level change. Across spatial scales, however, this knowledge is limited by the paucity and discrete character of available thickness observations. To obtain a spatially coherent distribution of the glacier ice thickness, interpolation or numerical models have to be used. Whilst the first phase of the Ice Thickness Models Intercomparison eXperiment (ITMIX) focused on approaches that estimate such spatial information from characteristics of the glacier surface alone, ITMIX2 sought insights for the capability of the models to extract information from a limited number of thickness observations. The analyses were designed around 23 test cases comprising both real-world and synthetic glaciers, with each test case comprising a set of 16 different experiments mimicking possible scenarios of data availability. A total of 13 models participated in the experiments. The results show that the inter-model variability in the calculated local thickness is high, and that for unmeasured locations, deviations of 16% of the mean glacier thickness are typical (median estimate, three-quarters of the deviations within 37% of the mean glacier thickness). This notwithstanding, limited sets of ice thickness observations are shown to be effective in constraining the mean glacier thickness, demonstrating the value of even partial surveys. Whilst the results are only weakly affected by the spatial distribution of the observations, surveys that preferentially sample the lowest glacier elevations are found to cause a systematic underestimation of the thickness in several models. Conversely, a preferential sampling of the thickest glacier parts proves effective in reducing the deviations. The response to the availability of ice thickness observations is characteristic to each approach and varies across models. On average across models, the deviation between modeled and observed thickness increase by 8.5% of the mean ice thickness every time the distance to the closest observation increases by a factor of 10. No single best model emerges from the analyses, confirming the added value of using model ensembles.

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