scholarly journals Seasonal Surface Change of Urumqi Glacier No. 1, Eastern Tien Shan, China, Revealed by Repeated High-Resolution UAV Photogrammetry

2021 ◽  
Vol 13 (17) ◽  
pp. 3398
Author(s):  
Puyu Wang ◽  
Hongliang Li ◽  
Zhongqin Li ◽  
Yushuo Liu ◽  
Chunhai Xu ◽  
...  
Keyword(s):  
Tien Shan ◽  
Surface Elevation ◽  
Surface Velocity ◽  
Elevation Change ◽  
The West ◽  
Glacier Surface ◽  
Surface Change ◽  
Ablation Area ◽  
Glacier Terminus ◽  
Surface Changes

The seasonal surface changes of glaciers in Tien Shan have seen little prior investigation despite the increase in geodetic studies of multi-year changes. In this study, we analyzed the potential of an Unmanned Aerial Vehicle (UAV) to analyze seasonal surface change processes of the Urumqi Glacier No. 1 in eastern Tien Shan. We carried out UAV surveys at the beginning and the end of the ablation period in 2018. The high-precision evolution of surface elevation, geodetic mass changes, surface velocity, and terminus change in the surveyed ablation area were correspondingly derived in combination with ground measurements, including stake/snow-pit observation and GPS measurement. The derived mean elevation change in the surveyed ablation area was −1.64 m, corresponding to the geodetic mass balance of approximately −1.39 m w.e. during the ablation period in 2018. The mean surface velocity was 3.3 m/yr and characterized by the spatial change of the velocity, which was less in the East Branch than in the West Branch. The UAV survey results were a little less than those from the ground measurements, and the correlation coefficient was 0.88 for the surface elevation change and 0.87 for surface displacement. The relative error of the glacier terminus change was 4.5% for the East Branch and 6.2% for the West Branch. These results show that UAV photogrammetry is ideal for assessing seasonal glacier surface changes and has a potential application in the monitoring of detailed glacier changes.

Multi-decadal ice-velocity and elevation changes of a monsoonal maritime glacier: Hailuogou glacier, China

2010 ◽  
Vol 56 (195) ◽  
pp. 65-74 ◽  
Author(s):  
Yong Zhang ◽  
Koji Fujita ◽  
Shiyin Liu ◽  
Qiao Liu ◽  
Xin Wang
Keyword(s):  
Thermal Emission ◽  
Surface Elevation ◽  
Aerial Photographs ◽  
Differential Gps ◽  
Glacier Surface ◽  
Ablation Area ◽  
Glacier Terminus ◽  
Digital Elevation ◽  
Elevation Changes ◽  
Ice Velocity

AbstractDigital elevation models (DEMs) of the ablation area of Hailuogou glacier, China, produced from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data obtained in 2009, differential GPS (DGPS) data surveyed in 2008 and aerial photographs acquired in 1966 and 1989 are differenced to estimate long- and short-term glacier surface elevation change (dh/dt). The mean dh/dt of the ablation area over 43 years (1966–2009) is −1.1 ± 0.4 m a−1. Since 1989 the thinning has accelerated significantly. Ice velocities measured by DGPS at 28 fixed stakes implanted in the ablation area increase with distance from the glacier terminus, ranging from 41.0 m a−1 approaching the glacier terminus to a maximum of 205.0 m a−1 at the base of an icefall. Our results reveal that the overall average ice velocity in the ablation area has undergone significant temporal variability over the past several decades. Changes in glacier surface elevation in the ablation area result from the combined effects of climate change and glacier dynamics, which are driven by different factors for different regions and periods.

scholarly journals Bayesian estimation of basal conditions on Rutford Ice Stream, West Antarctica, from surface data

2011 ◽  
Vol 57 (202) ◽  
pp. 315-324 ◽  
Author(s):  
Mélanie Raymond Pralong ◽  
G. Hilmar Gudmundsson
Keyword(s):  
Steady State ◽  
Surface Topography ◽  
Surface Elevation ◽  
Surface Velocity ◽  
West Antarctica ◽  
Elevation Change ◽  
Surface Geometry ◽  
Inference Problem ◽  
Ice Stream ◽  
Surface Data

AbstractThe determination of basal properties on ice streams from surface data is formulated as a Bayesian statistical inference problem. The theory is applied to a flowline on Rutford Ice Stream, West Antarctica. Estimates of bed topography and basal slipperiness are updated using measurements of surface topography and the horizontal and vertical components of the surface velocity. The surface topography is allowed to vary within measurement errors. We calculate the transient evolution of the surface until rates of surface elevation change are within limits given by measurements. For our final estimation of basal properties, modelled rates of elevation change are in full agreement with estimates of surface elevation changes. Results are discarded from a section of the flowline where the distribution of surface residuals is not consistent with error estimates. Apart from a general increase in basal slipperiness toward the grounding line, we find no evidence for any spatial variations in basal slipperiness. In particular, we find that short-scale variability (<10 × ice thickness) in surface topography and surface velocities can be reproduced by the model by variations in basal topography only. Assuming steady-state conditions, an almost perfect agreement is found between modelled and measured surface geometry, suggesting that Rutford Ice Stream is currently close to a steady state.

scholarly journals Glacier mass-balance determination by remote sensing and high-resolution modelling

2000 ◽  
Vol 46 (154) ◽  
pp. 491-498 ◽  
Author(s):  
Alun Hubbard ◽  
Ian Willis ◽  
Martin Sharp ◽  
Douglas Mair ◽  
Peter Nienow ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Mass Flux ◽  
Surface Elevation ◽  
Surface Velocity ◽  
Elevation Change ◽  
Flux Divergence ◽  
Flow Modelling ◽  
Surface Elevation Change ◽  
Divergence Field

AbstractAn indirect methodology for determining the distribution of mass balance at high spatial resolution using remote sensing and ice-flow modelling is presented. The method, based on the mass-continuity equation, requires two datasets collected over the desired monitoring interval: (i) the spatial pattern of glacier surface-elevation change, and (ii) the mass-flux divergence field. At Haut Glacier d’Arolla, Valais, Switzerland, the mass-balance distribution between September 1992 and September 1993 is calculated at 20 m resolution from the difference between the pattern of surface-elevation change derived from analytical photogrammetry and the mass-flux divergence field determined from three-dimensional, numerical flow modelling constrained by surface-velocity measurements. The resultant pattern of mass balance is almost totally negative, showing a strong dependence on elevation, but with large localized departures. The computed distribution of mass balance compares well (R2 = 0.91) with mass-balance measurements made at stakes installed along the glacier centre line over the same period. Despite the highly optimized nature of the flow-modelling effort employed in this study, the good agreement indicates the potential this method has as a strategy for deriving high spatial and temporal-resolution estimates of mass balance.

scholarly journals Net Budget and Flow of South Cascade Glacier, Washington

1965 ◽  
Vol 5 (41) ◽  
pp. 547-566 ◽  
Author(s):  
Mark F. Meier ◽  
W. V. Tangborn
Keyword(s):  
Steady State ◽  
Surface Elevation ◽  
Elevation Change ◽  
Glacier Surface ◽  
Surface Elevation Change ◽  
Long Valley ◽  
Valley Glacier ◽  
Ice Velocity ◽  
The Mean ◽  
Velocity Averages

AbstractIce velocity, net mass budget and surface elevation change data were collected over the length and width of a small (3.4 km. long) valley glacier from 1957 to 1964. Ice velocities range up to about 20 m./yr.; three prominent velocity maxima along the length of the glacier correspond to maxima in surface slope. Net mass budgets averaged over the glacier surface range between − 3.3 m. of water equivalent (1957–58) and +1.2 m. (1963–64). Except for the year 1960–61, curves of net budget versus altitude are parallel. During the period 1958–61 the glacier became thinner at a rate averaging 0.93 m./yr. The net budget and thinning data are internally consistent. Relations between emergence velocity, net budget and surface elevation change are examined at four specific points on the glacier surface and as functions of distance along the length of the glacier. Emergence velocity averages about −0.5 m. in the upper part of the glacier and about +1.0 m. in the lower part. Ice discharge and ice thickness are also calculated as functions of distance. The discharge reaches a peak of 8.8 × 105m.3of ice per year 2.2 km. from the head of the glacier. The mean thickness of the glacier is about 83 m. A steady-state distribution of net budget is used to calculate a steady-state discharge, which is 2.2 times larger than the present discharge.

scholarly journals Impact of varying debris cover thickness on ablation: a case study for Koxkar Glacier in the Tien Shan

2014 ◽  
Vol 8 (2) ◽  
pp. 377-386 ◽  
Author(s):  
M. Juen ◽  
C. Mayer ◽  
A. Lambrecht ◽  
H. Han ◽  
S. Liu
Keyword(s):  
Remote Sensing ◽  
Field Measurements ◽  
Tien Shan ◽  
Shielding Effect ◽  
Glacier Surface ◽  
Glacier Terminus ◽  
Covered Area ◽  
Debris Cover ◽  
High Resolution Satellite Imagery ◽  
Cover Thickness

Abstract. To quantify the ablation processes on a debris covered glacier, a simple distributed ablation model has been developed and applied to a selected glacier. For this purpose, a set of field measurements was carried out to collect empirical data. A morphometric analysis of the glacier surface enables us to capture statistically the areal distribution of topographic features that influence debris thickness and consequently ablation. Remote-sensing techniques, using high-resolution satellite imagery, were used to extrapolate the in situ point measurements to the whole ablation area and to map and classify melt-relevant surface types. As a result, a practically applicable method is presented that allows the estimation of ablation on a debris covered glacier by combining field data and remote-sensing information. The sub-debris ice ablation accounts for about 24% of the entire ice ablation, while the percentage of the moraine covered area accounts for approximately 32% of the entire glacierized area. Although the ice cliffs occupy only 1.7% of the debris covered area, the melt amount accounts for approximately 12% of the total sub-debris ablation and 2.5% of the total ablation respectively. Our study highlights the influence of debris cover on the response of the glacier terminus in a particular climate setting. Due to the fact that melt rates beyond 0.1 m of moraine cover are highly restricted, the shielding effect of the debris cover dominates over the temperature and elevation dependence of the ablation in the bare ice case.

scholarly journals Glacial changes of five southwest British Columbia icefields, Canada, mid-1980s to 1999

2008 ◽  
Vol 54 (186) ◽  
pp. 469-478 ◽  
Author(s):  
Jeffrey A. VanLooy ◽  
Richard R. Forster
Keyword(s):  
British Columbia ◽  
Satellite Images ◽  
Surface Elevation ◽  
Interferometric Synthetic Aperture Radar ◽  
Elevation Change ◽  
Glacier Terminus ◽  
M 10 ◽  
Digital Elevation ◽  
Surface Elevation Change ◽  
Elevation Changes

AbstractThis study adjusts and compares digital elevation models (DEMs) created from photogrammetric and interferometric synthetic aperture radar techniques to determine volume and surface elevation changes of five icefields in a remote region of southwest British Columbia, Canada, between the mid-1980s and 1999. Preliminary differences between the DEMs in ice-free and vegetation-free areas indicated variable elevation offsets with increasing altitude (11 m km−1) and with increasing slope (2.7 m (10°)−1). Results indicate a surface elevation change of −6.0 ± 2.7 m (−0.5 ± 0.2 m a−1) and a total volume loss of −19.4 ± 8.8 km3 (−1.5 ± 0.7 km3 a−1), which represents a potential sea-level rise contribution of 0.004 ± 0.002 mm a−1. Temperature and snowfall data from four nearby meteorological stations indicate that increased temperatures and decreased snowfall throughout the late 1980s and 1990s are a likely cause of the thinning. Glacier terminus positions were compared between a historical map (1927) and satellite images (1974, 1990/91 and 2000/01). All observed glaciers were in retreat between 1927 and 1974, as well as between 1990/91 and 2000/01, but many glaciers advanced or significantly slowed in their retreat between 1974 and 1990/91.

scholarly journals Influence of recent warming and ice dynamics on glacier surface elevations in the Canadian High Arctic, 1995–2014

2018 ◽  
Vol 64 (245) ◽  
pp. 450-464 ◽  
Author(s):  
COLLEEN A. MORTIMER ◽  
MARTIN SHARP ◽  
WESLEY VAN WYCHEN
Keyword(s):  
Land Surface ◽  
High Arctic ◽  
Surface Elevation ◽  
Surface Velocity ◽  
Glacier Surface ◽  
Ice Dynamics ◽  
Thickness Change ◽  
Near Surface ◽  
Elevation Changes ◽  
Moderate Resolution Imaging Spectroradiometer

ABSTRACTRepeat airborne laser altimetry measurements show widespread thinning (surface lowering) of glaciers in Canada's Queen Elizabeth Islands since 1995. Thinning rates averaged for 50 m elevation bins, were more than three times higher during the period 2005/06 to 2012/14 pentad than during the previous two pentads. Strongly negative thickness change (dh/dt) anomalies from 2005/06 to 2012/14, relative to the 1995–2012/14 mean, suggest that most of the measured thinning occurred during the most recent 5–6 year period when mean summer land surface temperatures (LSTs) were anomalously high and the mean summer black-sky shortwave broadband albedos (BSA) were anomalously low, relative to the 2000/01–15/16 period, and upper-air (700 hPa) and near surface (2 m) air temperatures were between 0.8°C and 1.5°C higher than 1995–2012 mean. Comparisons of dh/dt with mean summer LST and BSA measurements from the Moderate Resolution Imaging Spectroradiometer and with surface longitudinal strain rates computed from surface velocity fields derived from RADARSAT 1/2 and Landat-7 ETM + data suggest that surface elevation changes were driven mainly by changes in climate. An exception to this occurs along many fast-flowing outlet glaciers where ice dynamics appear also to have played an important role in surface elevation changes.

scholarly journals Detecting Short-Term Surface Melt on an Arctic Glacier Using UAV Surveys

2018 ◽  
Vol 10 (10) ◽  
pp. 1547 ◽  
Author(s):  
Eleanor Bash ◽  
Brian Moorman ◽  
Allison Gunther
Keyword(s):  
Mass Balance ◽  
Point Clouds ◽  
Glacier Mass Balance ◽  
Short Term ◽  
Glacier Surface ◽  
Surface Change ◽  
Glacier Ice ◽  
Arctic Glacier ◽  
Surface Changes

Current understanding of glacier mass balance changes under changing climate is limited by scarcity of in situ measurements in both time and space, as well as resolution of remote sensing products. Recent innovations in unmanned aerial vehicles (UAVs), as well as structure-from-motion photogrammetry (SfM), have led to increased use of digital imagery to derive topographic data in great detail in many fields, including glaciology. This study tested the capability of UAV surveys to detect surface changes over glacier ice during a three-day period in July 2016. Three UAV imaging missions were conducted during this time over 0.185 km 2 of the ablation area of Fountain Glacier, NU. These were processed with the SfM algorithms in Agisoft Photoscan Professional and overall accuracies of the resulting point clouds ranged from 0.030 to 0.043 m. The high accuracy of point clouds achieved here is primarily a result of a small ground sampling distance (0.018 m), and is also influenced by GPS precision. Glacier surface change was measured through differencing of point clouds and change was compared to ablation stake measurements. Surface change measured with the UAV-SfM method agreed with the coincident ablation stake measurements in most instances, with RMSE values of 0.033, 0.028, and 0.042 m for one-, two-, and three-day periods, respectively. Total specific melt over the study area measured with the UAV was 0.170 m water equivalent (w.e.), while interpolation of ablation measurements resulted in 0.144 m w.e. Using UAVs to measure small changes in glacier surfaces will allow for new investigations of distribution of mass balance measurements.

scholarly journals Surface Velocity Analysis of Surge Region of Karayaylak Glacier from 2014 to 2020 in the Pamir Plateau

2021 ◽  
Vol 13 (4) ◽  
pp. 774
Author(s):  
Yanfei Peng ◽  
Zhongqin Li ◽  
Chunhai Xu ◽  
Hui Zhang ◽  
Weixiao Han
Keyword(s):  
Accuracy Assessment ◽  
Meteorological Data ◽  
Maximum Velocity ◽  
Google Earth ◽  
Meteorological Station ◽  
Surface Velocity ◽  
Control Mechanisms ◽  
The West ◽  
Glacier Surface ◽  
Study Region

The west branch of Karayaylak Glacier (eastern Pamir Plateau) surged in May 2015, significantly impacting on local socio-economic development. This event was also of great significance for studies of surging glaciers. Using Sentinel-1 imagery analyzed by offset tracking, based on normalized cross-correlation (NCC), and with the support of the Google Earth Engine (GEE) platform, we quantified the ice surface velocity of the west branch and terminus of Karayaylak Glacier from 13 October 2014 to 17 October 2020. Sentinel-1 images were acquired at intervals of 12 or 24 days. We also used a three-dimensional (3-D) laser scanner to measure the velocity of 3 ablation stakes and 56 feature points in the study region from 15 August to 6 October 2015, for the purpose of accuracy assessment. We set up an automatic meteorological station to record the air temperature in the same period and combined this with data from Tashkurgan meteorological station from 1957 to 2015. Analysis of this dataset provided insights into the glacier surge mechanism, with the following conclusions. (1) Surface velocity of the west branch and terminus of Karayaylak Glacier increased sharply after October 2014. The velocity then dropped significantly in the two months after the surge, and stayed at low values for nearly a year. After 2017, the velocity was slightly higher than in the previous period. (2) The surge event occurred from 11 April to 17 May 2015; the average surface velocity in this phase attained 2395 m a−1 with a maximum velocity of 4265 m a−1 at the west branch terminus. (3) From 2017 to 2020, the velocity showed periodic annual changes. (4) Based on the meteorological data analysis, we conclude that this surge resulted from the interaction between thermal and hydrological control mechanisms. Simultaneously, we demonstrate the high potential of the GEE platform and Sentinel-1 data to extract glacier surface velocity.

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