Estimation of surface elevation changes at bare earth riverbank using differential DEM technique of UAV imagery data

2021 ◽  
Vol 17 (4) ◽  
Author(s):  
Norhafizi Mohamad ◽  
◽  
Anuar Ahmad ◽  
Ami Hassan Md Din ◽  
◽  
...  
Keyword(s):  
Surface Elevation ◽  
Elevation Changes ◽  
Imagery Data

scholarly journals Surface elevation changes during 2007–13 on Bowdoin and Tugto Glaciers, northwestern Greenland

2016 ◽  
Vol 62 (236) ◽  
pp. 1083-1092 ◽  
Author(s):  
SHUN TSUTAKI ◽  
SHIN SUGIYAMA ◽  
DAIKI SAKAKIBARA ◽  
TAKANOBU SAWAGAKI
Keyword(s):  
Mass Balance ◽  
Satellite Observations ◽  
Surface Elevation ◽  
Surface Mass Balance ◽  
Elevation Change ◽  
Predominant Role ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Elevation Changes ◽  
Negative Surface

ABSTRACTTo quantify recent thinning of marine-terminating outlet glaciers in northwestern Greenland, we carried out field and satellite observations near the terminus of Bowdoin Glacier. These data were used to compute the change in surface elevation from 2007 to 2013 and this rate of thinning was then compared with that of the adjacent land-terminating Tugto Glacier. Comparing DEMs of 2007 and 2010 shows that Bowdoin Glacier is thinning more rapidly (4.1 ± 0.3 m a−1) than Tugto Glacier (2.8 ± 0.3 m a−1). The observed negative surface mass-balance accounts for <40% of the elevation change of Bowdoin Glacier, meaning that the thinning of Bowdoin Glacier cannot be attributable to surface melting alone. The ice speed of Bowdoin Glacier increases down-glacier, reaching 457 m a−1 near the calving front. This flow regime causes longitudinal stretching and vertical compression at a rate of −0.04 a−1. It is likely that this dynamically-controlled thinning has been enhanced by the acceleration of the glacier since 2000. Our measurements indicate that ice dynamics indeed play a predominant role in the rapid thinning of Bowdoin Glacier.

scholarly journals LiDAR for monitoring mass movements in permafrost environments at the cirque Hinteres Langtal, Austria, between 2000 and 2008

2009 ◽  
Vol 9 (4) ◽  
pp. 1087-1094 ◽  
Author(s):  
M. Avian ◽  
A. Kellerer-Pirklbauer ◽  
A. Bauer
Keyword(s):  
High Surface ◽  
Surface Elevation ◽  
Surface Dynamics ◽  
Mass Wasting ◽  
Material Transport ◽  
Highly Active ◽  
Digital Terrain ◽  
Terrain Models ◽  
Field Evidence ◽  
Elevation Changes

Abstract. Permafrost areas receive more and more attention in terms of natural hazards in recent years due to ongoing global warming. Active rockglaciers are mixtures of debris and ice (of different origin) in high-relief environments indicating permafrost conditions for a substantial period of time. Style and velocity of the downward movement of this debris-ice-mass is influenced by topoclimatic conditions. The rockglacier Hinteres Langtalkar is stage of extensive modifications in the last decade as a consequence of an extraordinary high surface movement. Terrestrial laserscanning (or LiDAR) campaigns have been out once or twice per year since 2000 to monitor surface dynamics at the highly active front of the rockglacier. High resolution digital terrain models are the basis for annual and inter-annual analysis of surface elevation changes. Results show that the observed area shows predominantly positive surface elevation changes causing a consequent lifting of the surface over the entire period. Nevertheless a decreasing surface lifting of the observed area in the last three years leads to the assumption that the material transport from the upper part declines in the last years. Furthermore the rockglacier front is characterized by extensive mass wasting and partly disintegration of the rockglacier body. As indicated by the LiDAR results as well as from field evidence, this rockglacier front seems to represent a permafrost influenced landslide.

scholarly journals Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

2013 ◽  
Vol 7 (3) ◽  
pp. 797-816 ◽  
Author(s):  
T. O. Holt ◽  
N. F. Glasser ◽  
D. J. Quincey ◽  
M. R. Siegfried
Keyword(s):  
Antarctic Peninsula ◽  
Structural Changes ◽  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Shelves ◽  
The North ◽  
Surface Elevation Change ◽  
Elevation Changes ◽  
Negative Surface ◽  
The Antarctic

Abstract. George VI Ice Shelf (GVIIS) is located on the Antarctic Peninsula, a region where several ice shelves have undergone rapid breakup in response to atmospheric and oceanic warming. We use a combination of optical (Landsat), radar (ERS 1/2 SAR) and laser altimetry (GLAS) datasets to examine the response of GVIIS to environmental change and to offer an assessment on its future stability. The spatial and structural changes of GVIIS (ca. 1973 to ca. 2010) are mapped and surface velocities are calculated at different time periods (InSAR and optical feature tracking from 1989 to 2009) to document changes in the ice shelf's flow regime. Surface elevation changes are recorded between 2003 and 2008 using repeat track ICESat acquisitions. We note an increase in fracture extent and distribution at the south ice front, ice-shelf acceleration towards both the north and south ice fronts and spatially varied negative surface elevation change throughout, with greater variations observed towards the central and southern regions of the ice shelf. We propose that whilst GVIIS is in no imminent danger of collapse, it is vulnerable to ongoing atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

scholarly journals Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

2013 ◽  
Vol 7 (1) ◽  
pp. 373-417 ◽  
Author(s):  
T. O. Holt ◽  
N. F. Glasser ◽  
D. J. Quincey ◽  
M. R. Siegfried
Keyword(s):  
Antarctic Peninsula ◽  
Structural Changes ◽  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Shelves ◽  
The North ◽  
Surface Elevation Change ◽  
Elevation Changes ◽  
Negative Surface ◽  
The Antarctic

Abstract. George VI Ice Shelf (GVIIS) is located on the Antarctic Peninsula, a region where several ice shelves have undergone rapid breakup in response to atmospheric and oceanic warming. We use a combination of optical (Landsat), radar (ERS 1/2 SAR) and laser altimetry (GLAS) datasets to examine the response of GVIIS to environmental change and to offer an assessment on its future stability. The spatial and structural changes of GVIIS (ca. 1973 to ca. 2010) are mapped and surface velocities are calculated at different time periods (InSAR and optical feature tracking from 1989 to 2009) to document changes in the ice shelf's flow regime. Surface elevation changes are recorded between 2003 and 2008 using repeat track ICESat acquisitions. We note an increase in fracture extent and distribution at the south ice front, ice-shelf acceleration towards both the north and south ice fronts and spatially varied negative surface elevation change throughout, with greater variations observed towards the central and southern regions of the ice shelf. We propose that whilst GVIIS is in no imminent danger of collapse, it is vulnerable to on-going atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

The importance of slope correction for studying Greenland ice change using radar altimetry (CryoSat-2)

2020 ◽  
Author(s):  
Katarzyna Sejan ◽  
Bert Wouters ◽  
Michiel van den Broeke
Keyword(s):  
Slope Angle ◽  
Greenland Ice Sheet ◽  
Correction Method ◽  
Surface Elevation ◽  
Laser Altimetry ◽  
Radar Altimetry ◽  
Slope Correction ◽  
Long Time ◽  
Elevation Changes ◽  
Satellite Radar

&lt;p&gt;Satellite radar altimetry is one of the most important tools for monitoring changes in the mass balance of the world's ice sheets. Acquiring long time series of elevation changes is crucial, and the long lifetime of the CryoSat-2 mission has contributed wonderfully to this effort. However, once the CryoSat-2 mission ends, it will be important to bridge the gap between CryoSat-2 and future radar altimetry missions. IceSat2 data can help aid this effort, assuming that the appropriate processing techniques are used to allow the comparison of radar and laser altimetry. Furthermore, different altimetry techniques come with their own pitfalls, in radar altimetry signal penetration into the snowpack introduces ambiguity in the origin of reflected echo, a major issue not present in laser altimetry. It is therefore important to minimize this ambiguity by developing processing algorithms for the radar altimetry form CryoSat-2 mission, with a special attention on relating it to the IceSat2 mission. &amp;#160;&lt;/p&gt;&lt;p&gt;Focusing on Greenland Ice Sheet (GIS), we have developed a processing chain for the estimation of surface elevations and elevation changes from the ESA level-1 product (L1b) Baseline D. As a first step, we investigated the importance of Digital Elevation Model (DEM) in the slope correction algorithm and how it affects the estimated surface elevation.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The waveform retracker algorithm was developed following the method by Nilsson (2015) with a range of thresholds in the threshold retracker applied to the waveform. Knowing the estimated range and the altitude of the satellite at the time of the measurement, we calculated the corresponding surface elevation at the point of the wavelet reflection.&lt;/p&gt;&lt;p&gt;We apply a slope correction method by Hurkmans (2012), where displacement from the nadir location in x- and y- directions is calculated using the slope angle and aspect retrieved from a DEM, giving a new set of coordinates that represents the location of the estimated elevation. We use two sets of slope angle and aspect calculated from two DEMs, ArcticDEM Release 7 (Porter et al., 2018) and Greenland Ice Mapping Project (GIMP) DEM (Howat et al., 2017). Both DEMs are similar in terms of optical imagery data source, processing and resolution, however, they have been referenced to different laser altimetry data. We investigate this effect in the slope correction of radar altimetry from CryoSat2 mission.&lt;/p&gt;&lt;p&gt;We checked the two sets of slope correction data using IceSat-2 data (Smith et al., 2019) corresponding to the same time period, and selected by nearest point calculation. We analyze and discuss the differences between IceSat-2 data and CryoSat-2 data with slope correction using GIMP DEM or ArcticDEM.&lt;/p&gt;

Glacier surface elevation changes in Rongbuk Catchment of the Central Himalayas in the last four decades

2020 ◽  
Author(s):  
Qinghua Ye ◽  
Wei Nie ◽  
Yimin Chen ◽  
Gang Li ◽  
lide Tian ◽  
...  
Keyword(s):  
Climate Modeling ◽  
Melting Rate ◽  
Surface Elevation ◽  
High Mountain ◽  
Glacier Surface ◽  
Important Indicator ◽  
Central Himalayas ◽  
Glacier Melting ◽  
Elevation Changes ◽  
Thinning Rate

&lt;p&gt;Glaciers in the central Himalayas are important water resources for the downstream habitants, and accelerating melting of the high mountain glaciers speed up with continuous warming. We summerized the geodetic glacier surface elevation changes (Dh) by 6 data sets at different time periods during 1974-2016 in RongbukCatchment(RC) on the northern slope of Mt. Qomolangma (Mt. Everest) in the Central Himalayas. The result showed that glacier Dh varied with altitude and time, from -0.29 &amp;#177; 0.03m a&lt;sup&gt;-1&lt;/sup&gt; in 1974-2000, to -0.47 &amp;#177;0.24 m a&lt;sup&gt;-1&lt;/sup&gt; in 1974-2006,and -0.48 &amp;#177;0.16 m a&lt;sup&gt;-1&lt;/sup&gt; in 1974-2012. Dh increased to -0.60 &amp;#177; 0.20 m a&lt;sup&gt;-1&lt;/sup&gt; in 2000-2012, then decreased to-0.46 &amp;#177; 0.24 m a&lt;sup&gt;-1&lt;/sup&gt; in 2000-2014, and by -0.49 &amp;#177; 0.08 m a&lt;sup&gt;-1&lt;/sup&gt; in 2000-2016, showing a diverse rate being up - down- a little up. However, it generally presented a similar glacier thinning rate by -0.46~-0.49 m a&lt;sup&gt;-1&lt;/sup&gt; in the last four decades since 1970s in RC according to Dh&lt;sub&gt;1974-2006&lt;/sub&gt;, Dh&lt;sub&gt;1974-2012&lt;/sub&gt;, Dh&lt;sub&gt;2000-2014&lt;/sub&gt;, and Dh&lt;sub&gt;2000-2016&lt;/sub&gt;. Local meteorological observations revealed that, to a first order, the glacier thinning rate was kept the same pace with the number of annual melting days (MD). In spite of the obviously arising summer air temperature (T&lt;sub&gt;S&lt;/sub&gt;) in 2000-2014, a slowdown glacier melting rate by -391 mm w.e.a&lt;sup&gt;-1&lt;/sup&gt; occurred in 2000-2014 because of less melting days with more precipitation and less annual mean temperature(T&lt;sub&gt;m&lt;/sub&gt;). It shows that MD is another important indicator and controlling factor to evaluate or to estimate glacier melting trend, especially in hydrological or climate modeling.&lt;/p&gt;

Automatic mapping of land surface elevation changes from UAV-based imagery

2017 ◽  
Vol 38 (8-10) ◽  
pp. 2603-2622 ◽  
Author(s):  
Ivan Lizarazo ◽  
Víctor Angulo ◽  
Jorge Rodríguez
Keyword(s):  
Land Surface ◽  
Surface Elevation ◽  
Elevation Changes ◽  
Automatic Mapping

scholarly journals Modeling of firn compaction for estimating ice-sheet mass change from observed ice-sheet elevation change

2011 ◽  
Vol 52 (59) ◽  
pp. 1-7 ◽  
Author(s):  
Jun Li ◽  
H. Jay Zwally
Keyword(s):  
Accumulation Rate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Temporal Variations ◽  
Mass Change ◽  
Surface Elevation ◽  
Effective Density ◽  
Elevation Change ◽  
Surface Elevation Change ◽  
Elevation Changes

AbstractChanges in ice-sheet surface elevation are caused by a combination of ice-dynamic imbalance, ablation, temporal variations in accumulation rate, firn compaction and underlying bedrock motion. Thus, deriving the rate of ice-sheet mass change from measured surface elevation change requires information on the rate of firn compaction and bedrock motion, which do not involve changes in mass, and requires an appropriate firn density to associate with elevation changes induced by recent accumulation rate variability. We use a 25 year record of surface temperature and a parameterization for accumulation change as a function of temperature to drive a firn compaction model. We apply this formulation to ICESat measurements of surface elevation change at three locations on the Greenland ice sheet in order to separate the accumulation-driven changes from the ice-dynamic/ablation-driven changes, and thus to derive the corresponding mass change. Our calculated densities for the accumulation-driven changes range from 410 to 610 kgm–3, which along with 900 kgm–3 for the dynamic/ablation-driven changes gives average densities ranging from 680 to 790 kgm–3. We show that using an average (or ‘effective’) density to convert elevation change to mass change is not valid where the accumulation and the dynamic elevation changes are of opposite sign.

Sign in / Sign up

Export Citation Format

Share Document