scholarly journals Observations of widespread accelerated thinning in the upper reaches of Svalbard glaciers

2012 ◽  
Vol 6 (2) ◽  
pp. 1085-1115 ◽  
Author(s):  
T. D. James ◽  
T. Murray ◽  
N. E. Barrand ◽  
H. J. Sykes ◽  
A. J. Fox ◽  
...  
Keyword(s):  
Mass Loss ◽  
High Spatial Resolution ◽  
Entire Surface ◽  
Svalbard Archipelago ◽  
Ice Caps ◽  
Mountain Glaciers ◽  
Decadal Scale ◽  
Before And After ◽  
Elevation Data ◽  
Elevation Changes

Abstract. The measured rise in eustatic sea level over the 20th century was dominated by mass loss from the world's mountain glaciers and ice caps, and predictions suggest that these fresh water reservoirs will remain significant into the 21st century. However, estimates of this mass transfer to the ocean are based on a limited number of observations extrapolated to represent not only regional changes but often changes across individual glaciers. Combining high resolution elevation data from contemporary laser-altimetry surveys and archived aerial photography makes it possible to measure historical changes across a glacier's entire surface. Here we present a high spatial resolution time-series for six Arctic glaciers in the Svalbard Archipelago spanning 1961 to 2005. We find increasing thinning rates before and after 1990 with elevation losses occurring most notably in the glaciers' upper reaches. In the absence of a clear meteorological driver, we recommend further investigation into a possible albedo amplification of prevailing meteorological trends to explain these higher elevation changes, which could have important consequences on the region's mass balance due to the sensitivity of its hypsometric distribution. However, the strong influence of decadal-scale variability, while explaining lower rates of mass loss reported in earlier studies, highlights that caution must be exercised when interpreting thinning rates when averaged over long periods.

scholarly journals Precise DEM extraction from Svalbard using 1936 high oblique imagery

2018 ◽  
Vol 7 (4) ◽  
pp. 277-288 ◽  
Author(s):  
Luc Girod ◽  
Niels Ivar Nielsen ◽  
Frédérique Couderette ◽  
Christopher Nuth ◽  
Andreas Kääb
Keyword(s):  
Good Practice ◽  
Climate Change Impacts ◽  
Polar Regions ◽  
Svalbard Archipelago ◽  
Decadal Scale ◽  
Elevation Data ◽  
Practice Method ◽  
Angle Of View ◽  
Reliable Quantification ◽  
Norwegian Polar Institute

Abstract. Stretching time series further in the past with the best possible accuracy is essential to the understanding of climate change impacts and geomorphological processes evolving on decadal-scale time spans. In the first half of the twentieth century, large parts of the polar regions were still unmapped or only superficially so. To create cartographic data, a number of historic photogrammetric campaigns were conducted using oblique imagery, which is easier to work with in unmapped environments as collocating images is an easier task for the human eye given a more familiar viewing angle and a larger field of view. Even if the data obtained from such campaigns gave a good baseline for the mapping of the area, the precision and accuracy are to be considered with caution. Exploiting the possibilities arising from modern image processing tools and reprocessing the archives to obtain better data is therefore a task worth the effort. The oblique angle of view of the data is offering a challenge to classical photogrammetric tools, but the use of modern structure-from-motion (SfM) photogrammetry offers an efficient and quantitative way to process these data into terrain models. In this paper, we propose a good practice method for processing historical oblique imagery using free and open source software (MicMac and Python) and illustrate the process using images of the Svalbard archipelago acquired in 1936 by the Norwegian Polar Institute. On these data, our workflow provides 5 m resolution, high-quality elevation data (SD 2 m for moderate terrain) as well as orthoimages that allow for the reliable quantification of terrain change when compared to more modern data.

scholarly journals Elevation changes measured on Svalbard glaciers and ice caps from airborne laser data

2005 ◽  
Vol 42 ◽  
pp. 202-208 ◽  
Author(s):  
Jonathan L. Bamber ◽  
William Krabill ◽  
Vivienne Raper ◽  
Julian A. Dowdeswell ◽  
J. Oerlemans
Keyword(s):  
Mass Balance ◽  
Elevation Change ◽  
Svalbard Archipelago ◽  
Ice Caps ◽  
Airborne Laser ◽  
Air Temperatures ◽  
Lower Elevation ◽  
Elevation Changes ◽  
The Mean ◽  
Negative Balance

AbstractPrecise airborne laser surveys were conducted during spring in 1996 and 2002 on 17 ice caps and glaciers in the Svalbard archipelago covering the islands of Spitsbergen and Nordaustlandet. We present the derived elevation changes. Lower-elevation glaciers in south Spitsbergen show the largest thinning rates of ∼ 0.5 m a-1, while some of the higher, more northerly ice caps appear to be close to balance. The pattern of elevation change is complex, however, due to several factors including glacier aspect, microclimatological influences and the high natural annual variability in local accumulation and ablation rates. Anomalous changes were observed on Fridtjovbreen, which started surging in 1996, at the start of the measurement period. On this glacier, thinning (of > 0.6 m a-1) was observed in the accumulation area, coincident with thickening at lower elevations. Asymmetric thinning was found on two ice caps on Nordaustlandet, with the largest values on the eastern side of Vestfonna but the western slopes of Vegafonna. The mean elevation change for all ice masses was -0.19 m a-1 w.e., which is 1.6 times the net mass-balance value determined for the last 30 years. Using mass-balance sensitivity estimates for Svalbard suggests that the implied increase in negative balance is linked to warmer air temperatures in the late 1990s. Multiple linear regression suggests that mass balance is most closely correlated with latitude, rather than mean altitude or longitude.

scholarly journals Observations of enhanced thinning in the upper reaches of Svalbard glaciers

2012 ◽  
Vol 6 (6) ◽  
pp. 1369-1381 ◽  
Author(s):  
T. D. James ◽  
T. Murray ◽  
N. E. Barrand ◽  
H. J. Sykes ◽  
A. J. Fox ◽  
...  
Keyword(s):  
Mass Balance ◽  
Average Rate ◽  
Winter Precipitation ◽  
Svalbard Archipelago ◽  
Ice Surface ◽  
Considerable Research ◽  
Elevation Data ◽  
Elevation Changes ◽  
The Subject ◽  
Geodetic Mass Balance

Abstract. Changes in the volume and extent of land ice of the Svalbard archipelago have been the subject of considerable research since their sensitivity to changes in climate was first noted. However, the measurement of these changes is often necessarily based on point or profile measurements which may not be representative if extrapolated to a whole catchment or region. Combining high-resolution elevation data from contemporary laser-altimetry surveys and archived aerial photography makes it possible to measure historical changes across a glacier's surface without the need for extrapolation. Here we present a high spatial resolution time-series for six Arctic glaciers in the Svalbard archipelago spanning 1961 to 2005. We find high variability in thinning rates between sites with prevalent elevation changes at all sites averaging −0.59 ± 0.04 m a−1 between 1961–2005. Prior to 1990, ice surface elevation was changing at an average rate of −0.52 ± 0.09 m a−1 which decreased to −0.76 ± 0.10 m a−1 after 1990. Setting the elevation changes against the glaciers' altitude distribution reveals that significant increases in thinning rates are occurring most notably in the glaciers' upper reaches. We find that these changes are coincident with a decrease in winter precipitation at the Longyearbyen meteorological station and could reflect a decrease in albedo or dynamic response to lower accumulation. Further work is required to understand fully the causes of this increase in thinning rates in the glaciers' upper reaches. If on-going and occurring elsewhere in the archipelago, these changes will have a significant effect on the region's future mass balance. Our results highlight the importance of understanding the climatological context of geodetic mass balance measurements and demonstrate the difficulty of using index glaciers to represent regional changes in areas of strong climatological gradients.

scholarly journals Potential of RADARSAT-2 stereo radargrammetry for the generation of glacier DEMs

2016 ◽  
Vol 62 (233) ◽  
pp. 486-496 ◽  
Author(s):  
C. PAPASODORO ◽  
A. ROYER ◽  
A. LANGLOIS ◽  
E. BERTHIER
Keyword(s):  
Remote Sensing ◽  
Mass Loss ◽  
Mass Balance ◽  
Confidence Level ◽  
Ground Control ◽  
Control Points ◽  
Ice Caps ◽  
Ice Cap ◽  
Ground Control Points ◽  
Elevation Changes

ABSTRACTThe study of glaciers and ice caps in remote and cloudy regions remains difficult using current remote sensing tools. Here the potential of stereo radargrammetry (SRG) with RADARSAT-2 Wide Ultra-Fine images is explored for DEM extraction, elevation changes and mass-balance calculations on Barnes Ice Cap (Nunavut, Canada). Over low-relief terrain surrounding Barnes, a vertical precision of ~7 m (1σ confidence level) is measured, as well as an average vertical bias of ~4 m. Moreover, we show that the C-band penetration depth over the ice cap is insignificant at this time of the year (i.e. late ablation season). This is likely due to a wet surface and the presence of superimposed ice that leads to a surface radar response. Comparing the SRG DEMs with other datasets, an historical glacier-wide mass balance of −0.52 ± 0.19 m w.e. a−1is estimated for 1960–2013, whereas it decreases to −1.06 ± 0.84 m w.e. a−1between 2005 and 2013. This clear acceleration of mass loss is in agreement with other recent studies. Given its all-weather functionality and its possible use without ground control points, the RADARSAT-2 SRG technology represents an appropriate alternative for glacier monitoring in cloudy and remote regions.

scholarly journals The historical global sea-level budget

2011 ◽  
Vol 52 (59) ◽  
pp. 8-14 ◽  
Author(s):  
J.C. Moore ◽  
S. Jevrejeva ◽  
A. Grinsted
Keyword(s):  
Sea Level ◽  
Water Cycle ◽  
Greenland Ice Sheet ◽  
Ice Age ◽  
Ice Caps ◽  
Mountain Glaciers ◽  
Global Water Cycle ◽  
Decadal Scale ◽  
Global Sea Level

AbstractWe analyze the global sea-level budget since 1850. Good estimates of sea-level contributions from glaciers and small ice caps, the Greenland ice sheet and thermosteric sea level are available over this period, though considerable scope for controversy remains in all. Attempting to close the sea-level budget by adding the components results in a residual displaying a likely significant trend of ~0.37mma–1 from 1955 to 2005, which can, however, be reasonably closed using estimated melting from unsurveyed high-latitude small glaciers and ice caps. The sea-level budget from 1850 is estimated using modeled thermosteric sea level and inferences from a small number of mountain glaciers. This longer-term budget has a residual component that displays a rising trend likely associated with the end of the Little Ice Age, with much decadal-scale variability that is probably associated with variability in the global water cycle, ENSO and long-term volcanic impacts.

scholarly journals Recent mass balance of Purogangri ice cap, central Tibetan Plateau, by means of differential X-band SAR interferometry

2013 ◽  
Vol 7 (2) ◽  
pp. 1119-1139 ◽  
Author(s):  
N. Neckel ◽  
A. Braun ◽  
J. Kropáček ◽  
V. Hochschild
Keyword(s):  
Tibetan Plateau ◽  
Shuttle Radar Topography Mission ◽  
Climatic Conditions ◽  
Sar Interferometry ◽  
The Tibetan Plateau ◽  
Fine Grid ◽  
Ice Caps ◽  
Ice Cap ◽  
Elevation Data ◽  
Elevation Changes

Abstract. Due to their remoteness, altitude and harsh climatic conditions, little is known about the glaciological parameters of ice caps on the Tibetan Plateau (TP). This study presents an interferometrical approach aiming at surface elevation changes of Purogangri ice cap, located on the central TP. Purogangri ice cap covers an area of 397 ± 9.7 km2 and is the largest ice cap on the TP. Its behavior is determined by dry and cold continental climate suggesting a polar-type glacier regime. We employed data from the actual TerraSAR-X mission and its add-on for Digital Elevation Measurements (TanDEM-X) and compare it with elevation data from the Shuttle Radar Topography Mission (SRTM). These datasets are ideal for this approach as both datasets feature the same wavelength of 3.1 cm and are available at a fine grid spacing. Similar snow conditions can be assumed since the data were acquired in early February 2000 and late January 2012. The trend in glacier extend was extracted using a time series of Landsat data. Our results show a balanced mass budget for the studied time period which is in agreement with previous studies. Additionally, we detected an exceptional fast advance of one glacier tongue in the eastern part of the ice cap between 1999 and 2011.

scholarly journals Area, elevation and mass changes of the two southernmost ice caps of the Canadian Arctic Archipelago between 1952 and 2014

2015 ◽  
Vol 9 (2) ◽  
pp. 1667-1704
Author(s):  
C. Papasodoro ◽  
E. Berthier ◽  
A. Royer ◽  
C. Zdanowicz ◽  
A. Langlois
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Canadian Arctic ◽  
Baffin Island ◽  
Canadian Arctic Archipelago ◽  
Ice Caps ◽  
Ice Cap ◽  
Area Reduction ◽  
Elevation Changes ◽  
The Impact

Abstract. In the far south of the Canadian Arctic Archipelago (CAA), on the Meta Incognita Peninsula (Baffin Island, Nunavut, Canada), the small Grinnell and Terra Nivea ice caps have received little attention compared to the much larger ice masses further north. Their evolution can, however, give valuable information about the impact of the recent Arctic warming at lower latitudes (i.e. 62.5° N). In this paper, we measure historical and recent rates of area, elevation and mass changes of both ice caps using in-situ, airborne and spaceborne datasets. Results show that the Terra Nivea Ice Cap (TNIC) areal extent has decreased by 34% since the late 50s, while the Grinnell Ice Cap (GIC) extent was reduced by 20% since 1952. For both ice caps, rates of area reduction accelerated at the beginning of the 21st century. The glacier-wide mass balance for the GIC was −0.37 ± 0.21 m a−1 water equivalent (w.e.) for the 1952–2014 period, and −0.47 ± 0.16 m a−1 w.e. on the TNIC for the 1958/59–2014 period. More recently, the TNIC has experienced an accelerated rate of mass loss of −1.68 ± 0.36 m a−1 w.e. between 2007 and 2014. This rate is 5.6 times as negative when compared to the 1958/59–2007 period (−0.30 ± 0.19 m a−1 w.e.) and 2 times as negative when compared to the mass balance of other glaciers in the southern parts of Baffin Island over the 2003–2009 period. A similar acceleration in mass loss is suspected for the GIC, given the calculated elevation changes and the proximity.

Fullerene-like Nanoparticles of WS2 as a Promising Protection from Erosive Wear of Gun Bore Nozzles

2020 ◽  
Vol 16 (1) ◽  
pp. 62-70 ◽  
Author(s):  
Narimane Rezgui ◽  
Danica Simić ◽  
Choayb Boulahbal ◽  
Dejan Micković
Keyword(s):  
Mass Loss ◽  
Solid Lubricant ◽  
Erosive Wear ◽  
Mechanical Resistance ◽  
Protective Function ◽  
Protective Layers ◽  
Total Mass Loss ◽  
Mass Losses ◽  
Before And After ◽  
Tube Life

Background: Erosive wear causes increase in the bore diameter of firearms barrels and nozzles. Most responsible factors for this erosion are friction and heat generated during the shot. Protection from erosive wear is very important for gun tube life cycle, and various protection methods are used: adding phlegmatizers in gunpowder composition or applying protective layers on the gun bore inner surface. Objective: In this research, a possibility is examined to protect the surface of a nozzle exposed to gunpowder erosion applying a layer of tungsten disulfide fullerene-like nanoparticles, IF-WS2, known as outstanding solid lubricant of a great mechanical resistance. Methods: Nanoparticles on the nozzle surface before and after the gunfire tests were observed using scanning electron microscopy/energy dispersive X-ray spectroscopy. Gunfire tests were performed on designed erosion device. Temperatures in the defined position near the affected surface were measured with thermocouples and compared for the nozzles with and without nanoprotection, as well as the nozzle mass loss after each round. Results: For the sample with IF-WS2 lower temperatures after firing and lower mass losses were observed. Mass loss after first round was 25.6% lower for the sample with protective nanoparticles layer, and the total mass loss was about 5% lower after five rounds. After the first round the nozzle without IF-WS2 was heated up to a temperature which was for 150.8°C higher than the nozzle with IF-WS2. Conclusion: Protective function of IF-WS2 is the most pronounced for the first round. The observed results encourage its further application in firearms gun bores protection.

scholarly journals Mountain glaciers and ice caps around Antarctica make a large sea-level rise contribution

2009 ◽  
Vol 36 (7) ◽  
pp. n/a-n/a ◽  
Author(s):  
Regine Hock ◽  
Mattias de Woul ◽  
Valentina Radić ◽  
Mark Dyurgerov
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Caps ◽  
Mountain Glaciers

scholarly journals An optimized method to calculate the geodetic mass balance of mountain glaciers

2018 ◽  
Vol 64 (248) ◽  
pp. 917-931 ◽  
Author(s):  
RUBÉN BASANTES-SERRANO ◽  
ANTOINE RABATEL ◽  
CHRISTIAN VINCENT ◽  
PASCAL SIRGUEY
Keyword(s):  
Spatial Variability ◽  
Mass Balance ◽  
Mean Difference ◽  
Full Density ◽  
Elevation Change ◽  
Low Contrast ◽  
Mountain Glaciers ◽  
Elevation Changes ◽  
Geodetic Mass Balance ◽  
Similar Accuracy

ABSTRACTUnderstanding the effects of climate on glaciers requires precise estimates of ice volume change over several decades. This is achieved by the geodetic mass balance computed by two means: (1) the digital elevation model (DEM) comparison (SeqDEM) allows measurements over the entire glacier, however the low contrast over glacierized areas is an issue for the DEM generation through the photogrammetric techniques and (2) the profiling method (SePM) is a faster alternative but fails to capture the spatial variability of elevation changes. We present a new framework (SSD) that relies upon the spatial variability of the elevation change to densify a sampling network to optimize the surface-elevation change quantification. Our method was tested in two small glaciers over different periods. We conclude that the SePM overestimates the elevation change by ~20% with a mean difference of ~1.00 m (root mean square error (RMSE) = ~3.00 m) compared with results from the SeqDEM method. A variogram analysis of the elevation changes showed a mean difference of <0.10 m (RMSE = ~2.40 m) with SSD approach. A final assessment on the largest glacier in the French Alps confirms the high potential of our method to compute the geodetic mass balance, without going through the generation of a full-density DEM, but with a similar accuracy than the SeqDEM approach.

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