Classification and kinematics of the Planpincieux Glacier break-offs using photographic time-lapse analysis

Daniele Giordan; Niccolò Dematteis; Paolo Allasia; Elena Motta

doi:10.1017/jog.2019.99

Classification and kinematics of the Planpincieux Glacier break-offs using photographic time-lapse analysis

Journal of Glaciology ◽

10.1017/jog.2019.99 ◽

2020 ◽

Vol 66 (256) ◽

pp. 188-202 ◽

Cited By ~ 2

Author(s):

Daniele Giordan ◽

Niccolò Dematteis ◽

Paolo Allasia ◽

Elena Motta

Keyword(s):

High Velocity ◽

Cross Correlation ◽

Positive Relationship ◽

Time Lapse ◽

Glacier Terminus ◽

Single Lens ◽

Speed Up ◽

Mont Blanc Massif ◽

Surface Kinematics

AbstractHerein, we present results obtained from time-lapse imagery acquired by a digital single-lens reflex camera during 2014–18 used to monitor the Planpincieux Glacier on the Italian side of the Grandes Jorasses (Mont Blanc massif). We processed the images using image cross-correlation to measure the surface kinematics of the most active lobe of the glacier that presents a high velocity and frequent ice detachments. During the monitoring, we observed two or three periods of sharp acceleration per year that culminated with large break-offs followed by analogous decelerations. Overall, we registered more than 350 failures with a volume >100 m3, of which, 14 events had volumes larger than 10 000 m3. The study identified a monotonic positive relationship between the velocity and failure volume that may be used to estimate the volume of the collapses before an event. We identified the thresholds of velocity and acceleration that characterise the activation of the speed-up periods. The study allowed the characterisation of three different instability processes that lead to the break-off of ice chunks from the glacier terminus: (i) disaggregation, (ii) slab fracture and (iii) water tunnelling failure which can be differentiated based on the rheology, the volume involved and the trigger process.

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Comparison of seismic interferometry techniques for the retrieval of seismic body waves in CO2 sequestration monitoring

Journal of Geophysics and Engineering ◽

10.1093/jge/gxz079 ◽

2019 ◽

Vol 16 (6) ◽

pp. 1094-1115

Author(s):

Haitao Cao ◽

Roohollah Askari

Keyword(s):

Co2 Sequestration ◽

Field Data ◽

Cross Correlation ◽

Time Lapse ◽

Body Waves ◽

Seismic Interferometry ◽

Storage Site ◽

Phase Information ◽

Wave Data ◽

The Cross

Abstract Ambient noise seismic interferometry performed by cross-correlation has been proven to be a potential cost-effective technique for geological studies. To improve the resolution of images created by interferometry, additional techniques using deconvolution and cross-coherence have been introduced. While all three methods have previously been evaluated using surface wave data for shear-wave imaging of the near surface, comparatively little study has been devoted to assess the three methods for the retrieval of body waves in reflection surveys for time-lapse application. Moreover, although the application of seismic interferometry to CO2 sequestration by cross-correlation has been investigated by many researchers, to our knowledge, similar time-lapse studies have not been conducted using deconvolution and cross-coherence methods. We evaluate the three methods of cross-correlation, deconvolution and cross-coherence for the retrieval of phase information contained in virtual seismic records by applying seismic interferometry to synthetic data, using a model reservoir before and after CO2 injection. By examining two approaches of regularization and smoothing factors to suppress spurious reflection events observed on the deconvolution and cross-coherence results, we note that both approaches provide similar results. We investigate noise effects by adding random noise independently at each geophone. Finally, we apply these techniques to field data recorded near the CO2 storage site in Ketzin, Germany. For both our numerical and field data studies, we find that the cross-coherence technique retrieves the phase information of body-wave data more effectively than the cross-correlation and deconvolution techniques, and is less sensitive to uncorrelated noise from shallow sources.

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Mapping tide-water glacier dynamics in East Greenland using Landsat data

Journal of Glaciology ◽

10.1017/s0022143000034900 ◽

1995 ◽

Vol 41 (139) ◽

pp. 584-595 ◽

Cited By ~ 40

Author(s):

John L. Dwyer

Keyword(s):

Cross Correlation ◽

Drainage Basin ◽

Surface Velocity ◽

Key Factors ◽

Remotely Sensed Data ◽

East Greenland ◽

Ice Surface ◽

Glacier Terminus ◽

Glacier Dynamics ◽

Continuous Presence

AbstractLandsat multispectral scanner and thematic mapper images were co-registered For the Kangerdlugssuaq Fjord region in East Greenland and were used to map glacier drainage-basin areas, changes in the positions of tide-water glacier termini and to estimate surface velocities of the larger tide-water glaciers. Statistics were compiled to document distance and area changes to glacier termini. The methodologies developed in this study are broadly applicable to the investigation of tide-water glaciers in other areas. The number of images available for consecutive years and the accuracy with which images are co-registered are key factors that influence the degree to which regional glacier dynamics can be characterized using remotely sensed data.Three domains of glacier state were interpreted: net increase in terminus area in the southern part of the study area, net loss of terminus area for glaciers in upper Kangerdlugssuaq Fjord and a slight loss of glacier terminus area northward from Ryberg Fjord. Local increases in the concentrations of drifting icebergs in the fjords coincide with the observed extension of glacier termini positions Ice-surface velocity estimates were derived for several glaciers using automated image cross-correlation techniques The velocity determined for Kangerdlugssuaq Gletscher is approximately 5.0 km a−1and that for Kong Christian IV Gletscher is 0.9 km a−1. The continuous presence of icebergs and brash ice in front of these glaciers indicates sustained rates of ice-front calving.

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A Speed-Up Way of Template Matching Using Normalized Cross-Correlation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.313-314.1188 ◽

2013 ◽

Vol 313-314 ◽

pp. 1188-1191 ◽

Cited By ~ 4

Author(s):

Fang Chen ◽

Cun Ji Zhang ◽

Bin Wen Zhao ◽

Jin Fei Shi

Keyword(s):

Template Matching ◽

Cross Correlation ◽

Correlation Method ◽

Block Matching ◽

Conventional Approach ◽

Projection Algorithm ◽

Experimental Result ◽

Gray Scale ◽

Normalized Cross Correlation ◽

Speed Up

One classic algorithm usedin template matching is normalized cross correlation method. It often achieveshigh precision. But it does not meet speed requirements for time-criticalapplications. To solve that issue, a speed-up way of template matching isproposed. The fast matching way bases on pyramid hierarchical searchingalgorithm. It adopts two template matching methods to match images, which baseon rough matching proceeds local matching precision. Firstly, the coarsematching is performed based on gray-scale projection algorithm. Secondly, theprecise matching is made based on several small block matching. The new way iscompared to conventional approach without pyramid hierarchical searching byexperiments. Experimental result demonstrates that the proposed way efficientlyimproves the speed of template matching and the precision is unchanged.

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PyTrx: A Python toolbox for deriving velocities, surface areas and line measurements from oblique imagery in glacial environments

10.5194/gi-2018-28 ◽

2018 ◽

Cited By ~ 2

Author(s):

Penelope How ◽

Nicholas R. J. Hulton ◽

Lynne Buie

Keyword(s):

Projective Transformation ◽

Time Lapse ◽

Transformation Model ◽

Ice Flow ◽

Surface Areas ◽

Supraglacial Lakes ◽

Glacier Terminus ◽

Glacial Environments ◽

Spatio Temporal ◽

Flow Velocities

Abstract. Terrestrial time-lapse photogrammetry is a rapidly growing method for deriving measurements from glacial environments because it provides high spatio-temporal resolution records of change. However, glacial photogrammetry toolboxes are limited currently. Without prior knowledge in photogrammetry and computer coding, they are used primarily to calculate ice flow velocities or to serve as qualitative records. PyTrx (available at https://github.com/PennyHow/PyTrx) is presented here as a Python-alternative toolbox to widen the range of photogrammetry toolboxes on offer to the glaciology community. The toolbox holds core photogrammetric functions for point seeding, feature-tracking, image registration, and georectification (using a planar projective transformation model). In addition, PyTrx facilitates areal and line measurements, which can be detected from imagery using either an automated or manual approach. Examples of PyTrx's applications are demonstrated using time-lapse imagery from Kronebreen and Tunabreen, two tidewater glaciers in Svalbard. Products from these applications include ice flow velocities, surface areas of supraglacial lakes and meltwater plumes, and glacier terminus profiles.

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Modelled glacier dynamics over the last quarter of a century at Jakobshavn Isbræ

The Cryosphere ◽

10.5194/tc-10-597-2016 ◽

2016 ◽

Vol 10 (2) ◽

pp. 597-611 ◽

Cited By ~ 9

Author(s):

Ioana S. Muresan ◽

Shfaqat A. Khan ◽

Andy Aschwanden ◽

Constantine Khroulev ◽

Tonie Van Dam ◽

...

Keyword(s):

Three Dimensional ◽

Significant Progress ◽

Outlet Glacier ◽

The Past ◽

Glacier Terminus ◽

Subsequent Response ◽

Glacier Dynamics ◽

Speed Up ◽

Break Up ◽

Bed Slope

Abstract. Observations over the past 2 decades show substantial ice loss associated with the speed-up of marine-terminating glaciers in Greenland. Here we use a regional three-dimensional outlet glacier model to simulate the behaviour of Jakobshavn Isbræ (JI) located in western Greenland. Our approach is to model and understand the recent behaviour of JI with a physical process-based model. Using atmospheric forcing and an ocean parametrization we tune our model to reproduce observed frontal changes of JI during 1990–2014. In our simulations, most of the JI retreat during 1990–2014 is driven by the ocean parametrization used and the glacier's subsequent response, which is largely governed by bed geometry. In general, the study shows significant progress in modelling the temporal variability of the flow at JI. Our results suggest that the overall variability in modelled horizontal velocities is a response to variations in terminus position. The model simulates two major accelerations that are consistent with observations of changes in glacier terminus. The first event occurred in 1998 and was triggered by a retreat of the front and moderate thinning of JI prior to 1998. The second event, which started in 2003 and peaked in the summer 2004, was triggered by the final break-up of the floating tongue. This break-up reduced the buttressing at the JI terminus that resulted in further thinning. As the terminus retreated over a reverse bed slope into deeper water, sustained high velocities over the last decade have been observed at JI. Our model provides evidence that the 1998 and 2003 flow accelerations are most likely initiated by the ocean parametrization used but JI's subsequent dynamic response was governed by its own bed geometry. We are unable to reproduce the observed 2010–2012 terminus retreat in our simulations. We attribute this limitation to either inaccuracies in basal topography or to misrepresentations of the climatic forcings that were applied. Nevertheless, the model is able to simulate the previously observed increase in mass loss through 2014.

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Tidewater calving

Journal of Glaciology ◽

10.3189/s0022143000004226 ◽

1996 ◽

Vol 42 (141) ◽

pp. 375-385 ◽

Cited By ~ 14

Author(s):

С.J. Van Der Veen

Keyword(s):

Water Depth ◽

Fold Increase ◽

Actual Rate ◽

Tidewater Glaciers ◽

Glacier Terminus ◽

Tidewater Glacier ◽

Iceberg Calving ◽

Speed Up ◽

Calving Rate ◽

Subglacial Drainage

AbstractData from Columbia Glacier are used to identify processes that control calving from a temperate tidewater glacier and to re-evaluate models that have been proposed to describe iceberg calving. Since 1981, Columbia Glacier has been retreating rapidly, with an almost seven-fold increase in calving rate from the mid-1970s to 1993. At the same time, the speed of the glacier increased almost as much, so that the actual rate of retreat increased more slowly. According to the commonly accepted model, the calving rate is linearly related to the water depth at the terminus, with retreat of the glacier snout into deeper water, leading to larger calving rates and accelerated retreat. The Columbia Glacier data show that the calving rate is not simply linked to observed quantities such as water depth or stretching rate near the terminus. During the retreat, the thickness at the terminus appears to be linearly correlated with the water depth; at the terminus, the thickness in excess of flotation remained at about 50 m. This suggests that retreat may be initiated when the terminal thickness becomes too small, with the rate of retreat controlled by the rate at which the snout is thinning and by the basal slope. The implication is that the rapid retreat of Columbia Glacier (and other comparable tidewater glaciers) is not the result of an increase in calving as the glacier retreated into deeper water. Instead, the retreat was initiated and maintained by thinning of the glacier. For Columbia Glacier, the continued thinning is probably associated with the increase in glacier speed and retreat may be expected to continue as long as these large speeds are maintained. It is not clear what mechanism may be responsible for the speed-up but the most likely candidate is a change in basal conditions or subglacial drainage. Consequently, the behavior of tidewater glaciers may be controlled by processes acting at the glacier bed rather than by what happens at the glacier terminus.

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FAST TIME DELAY NEURAL NETWORKS

International Journal of Neural Systems ◽

10.1142/s0129065705000414 ◽

2005 ◽

Vol 15 (06) ◽

pp. 445-455 ◽

Cited By ~ 3

Author(s):

HAZEM M. EL-BAKRY ◽

QIANGFU ZHAO

Keyword(s):

Neural Networks ◽

Time Delay ◽

Frequency Domain ◽

Cross Correlation ◽

Input Pattern ◽

Fast Time ◽

New Approach ◽

Entire Data ◽

Speed Up ◽

Simulation Results

This paper presents a new approach to speed up the operation of time delay neural networks. The entire data are collected together in a long vector and then tested as a one input pattern. The proposed fast time delay neural networks (FTDNNs) use cross correlation in the frequency domain between the tested data and the input weights of neural networks. It is proved mathematically and practically that the number of computation steps required for the presented time delay neural networks is less than that needed by conventional time delay neural networks (CTDNNs). Simulation results using MATLAB confirm the theoretical computations.

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Simultaneous disintegration of outlet glaciers in Porpoise Bay (Wilkes Land), East Antarctica, and the long-term speed-up of Holmes Glacier

10.5194/tc-2016-151 ◽

2016 ◽

Cited By ~ 2

Author(s):

B. W. J. Miles ◽

C. R. Stokes ◽

S. S. R. Jamieson

Keyword(s):

Sea Ice ◽

East Antarctica ◽

High Temporal Resolution ◽

Ice Flow ◽

Outlet Glacier ◽

Ice Shelves ◽

Glacier Terminus ◽

Wilkes Land ◽

Speed Up

Abstract. The floating ice shelves and glacier tongues which fringe the Antarctic continent are important because they help buttress ice flow from the ice sheet interior. Dynamic feedbacks associated with glacier calving have the potential to reduce buttressing and subsequently increase ice flow into the ocean. However, there are few high temporal resolution studies on glacier calving, especially in East Antarctica. Here we use remote sensing to investigate monthly glacier terminus change across six marine-terminating outlet glaciers in Porpoise Bay (−76° S, 128° E), Wilkes Land (East Antarctica), between November 2002 and March 2012. This reveals a large simultaneous calving event in January 2007, resulting in a total of ~ 2900 km2 of ice being removed from glacier tongues. Our observations suggest that sea-ice must be removed from glacier termini for any form of calving to take place, and we link this major calving event to a rapid break-up of the multi-year sea-ice which usually occupies Porpoise Bay. Using sea-ice concentrations as a proxy for glacier calving, and by analysing available satellite imagery stretching back to 1963, we reconstruct the long-term calving activity of the largest glacier in Porpoise Bay: Holmes (West) Glacier. This reveals that its present-day velocity (~ 1450 m a−1) is approximately 50 % faster than between 1963 and 1973 (~ 900 m a−1). We also observed the start of a large calving event in Porpoise Bay in March 2016 that is consistent with our reconstructions of the periodicity of major calving events. These results highlight the importance of sea-ice in modulating outlet glacier calving and velocity in East Antarctica.

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Correlation and Calibration of 4D Seismic Vintages for Effective Postproduction Intervention

Journal of Geography Environment and Earth Science International ◽

10.9734/jgeesi/2021/v25i330275 ◽

2021 ◽

pp. 35-46

Author(s):

B. T. Ojo ◽

M. T. Olowokere ◽

M. I. Oladapo

Keyword(s):

Seismic Data ◽

Cross Correlation ◽

Time Lapse ◽

Time Shift ◽

Accurate Analysis ◽

Hydrocarbon Production ◽

Matching Process ◽

Future Production ◽

Correlation Threshold ◽

4D Seismic

Poor or low data quality usually has an adverse effect on the quantitative usage of (4D) seismic data for accurate analysis. Repeatability of 4D Seismic or time-lapse survey is considered as a vital tool for effective, potent, and impressive monitoring of productivity of reservoirs. Inconsistencies and disagreement of ‘time-lapse’ data will greatly affect the accuracy and outcome of research when comparing two or more seismic surveys having low repeatability. Correlation is a statistic procedure that measures the linear relation between all points of two variables. Error due to acquisition and processing must be checked for before interpretation in order to minimize exploration failure and the number of dry holes drilled. The seismic data available for this study comprises of 779 crosslines and 494 inlines. The 4D seismic data consisting of the base Seismic shot in 1998 before production and the monitor Seismic shot in 2010 at different stages of hydrocarbon production were cross correlated to ascertain repeatability between the two vintages. A global average matching process was applied while phase and time shift were estimated using the Russell-Liang technique. Two pass full shaping filters were applied for the phase matching. Maximum and minimum ‘cross-correlation’ are 0.85 (85%) and 0.60 (60%) respectively. Statistics of the ‘cross-correlation’ shift show standard deviation (0.3), variance (0.12), and root mean square (0.78). For high percentage repeatability and maximum correlations, the requested correlation threshold is 0.7 but 1 and 0.99 were obtained for the first and the second matching respectively. Conclusively, the overall results show that there is high repeatability between the 4D seismic data used and the data can be employed conveniently for accurate ‘time-lapse’ (future) production monitoring and investigation on the field.

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