scholarly journals Elevation and elevation-change maps of Fountain Creek, southeastern Colorado, 2015-20

2021 ◽  
Author(s):  
Laura A. Hempel ◽  
Andrea L. Creighton ◽  
Andrew R. Bock
Keyword(s):  
Elevation Change

scholarly journals GNSS Profile from the Greenland Korth Expeditions in the Context of Satellite Data

2021 ◽  
Vol 11 (3) ◽  
pp. 1115
Author(s):  
Aleš Bezděk ◽  
Jakub Kostelecký ◽  
Josef Sebera ◽  
Thomas Hitziger
Keyword(s):  
Ice Sheet ◽  
Satellite Observations ◽  
Elevation Change ◽  
Gradual Decline ◽  
Satellite Gravimetry ◽  
Surface Elevation Change ◽  
Satellite Radar ◽  
Gnss Measurements ◽  
Gnss Data ◽  
Satellite Radar Altimetry

Over the last two decades, a small group of researchers repeatedly crossed the Greenland interior skiing along a 700-km long route from east to west, acquiring precise GNSS measurements at exactly the same locations. Four such elevation profiles of the ice sheet measured in 2002, 2006, 2010 and 2015 were differenced and used to analyze the surface elevation change. Our goal is to compare such locally measured GNSS data with independent satellite observations. First, we show an agreement in the rate of elevation change between the GNSS data and satellite radar altimetry (ERS, Envisat, CryoSat-2). Both datasets agree well (2002–2015), and both correctly display local features such as an elevation increase in the central part of the ice sheet and a sharp gradual decline in the surface heights above Jakobshavn Glacier. Second, we processed satellite gravimetry data (GRACE) in order for them to be comparable with local GNSS measurements. The agreement is demonstrated by a time series at one of the measurement sites. Finally, we provide our own satellite gravimetry (GRACE, GRACE-FO, Swarm) estimate of the Greenland mass balance: first a mild decrease (2002–2007: −210 ± 29 Gt/yr), then an accelerated mass loss (2007–2012: −335 ± 29 Gt/yr), which was noticeably reduced afterwards (2012–2017: −178 ± 72 Gt/yr), and nowadays it seems to increase again (2018–2019: −278 ± 67 Gt/yr).

scholarly journals Heterogeneous spatial and temporal pattern of surface elevation change and mass balance of the Patagonian ice fields between 2000 and 2016

2019 ◽  
Vol 13 (9) ◽  
pp. 2511-2535 ◽  
Author(s):  
Wael Abdel Jaber ◽  
Helmut Rott ◽  
Dana Floricioiu ◽  
Jan Wuite ◽  
Nuno Miranda
Keyword(s):  
Spatial Pattern ◽  
Mass Balance ◽  
Temporal Trend ◽  
Sar Interferometry ◽  
Surface Elevation ◽  
Radar Signal ◽  
Elevation Change ◽  
Mass Losses ◽  
Digital Elevation ◽  
Surface Elevation Change

Abstract. The northern and southern Patagonian ice fields (NPI and SPI) have been subject to accelerated retreat during the last decades, with considerable variability in magnitude and timing among individual glaciers. We derive spatially detailed maps of surface elevation change (SEC) of NPI and SPI from bistatic synthetic aperture radar (SAR) interferometry data of the Shuttle Radar Topography Mission (SRTM) and TerraSAR-X add-on for Digital Elevation Measurements (TanDEM-X) for two epochs, 2000–2012 and 2012–2016, and provide data on changes in surface elevation and ice volume for the individual glaciers and the ice fields at large. We apply advanced TanDEM-X processing techniques allowing us to cover 90 % and 95 % of the area of NPI and 97 % and 98 % of SPI for the two epochs, respectively. Particular attention is paid to precisely co-registering the digital elevation models (DEMs), accounting for possible effects of radar signal penetration through backscatter analysis and correcting for seasonality biases in case of deviations in repeat DEM coverage from full annual time spans. The results show a different temporal trend between the two ice fields and reveal a heterogeneous spatial pattern of SEC and mass balance caused by different sensitivities with respect to direct climatic forcing and ice flow dynamics of individual glaciers. The estimated volume change rates for NPI are -4.26±0.20 km3 a−1 for epoch 1 and -5.60±0.74 km3 a−1 for epoch 2, while for SPI these are -14.87±0.52 km3 a−1 for epoch 1 and -11.86±1.99 km3 a−1 for epoch 2. This corresponds for both ice fields to an eustatic sea level rise of 0.048±0.002 mm a−1 for epoch 1 and 0.043±0.005 mm a−1 for epoch 2. On SPI the spatial pattern of surface elevation change is more complex than on NPI and the temporal trend is less uniform. On terminus sections of the main calving glaciers of SPI, temporal variations in flow velocities are a main factor for differences in SEC between the two epochs. Striking differences are observed even on adjoining glaciers, such as Upsala Glacier, with decreasing mass losses associated with slowdown of flow velocity, contrasting with acceleration and increase in mass losses on Viedma Glacier.

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 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.

scholarly journals Detailed ice loss pattern in the northern Antarctic Peninsula: widespread decline driven by ice front retreats

2014 ◽  
Vol 8 (6) ◽  
pp. 2135-2145 ◽  
Author(s):  
T. A. Scambos ◽  
E. Berthier ◽  
T. Haran ◽  
C. A. Shuman ◽  
A. J. Cook ◽  
...  
Keyword(s):  
Mass Loss ◽  
Antarctic Peninsula ◽  
Snow Accumulation ◽  
Stereo Image ◽  
Western Coast ◽  
Elevation Change ◽  
Ice Shelf ◽  
Laser Altimetry ◽  
Ice Volume ◽  
Basin Scale

Abstract. The northern Antarctic Peninsula (nAP, < 66° S) is one of the most rapidly changing glaciated regions on earth, yet the spatial patterns of its ice mass loss at the glacier basin scale have to date been poorly documented. We use satellite laser altimetry and satellite stereo-image topography spanning 2001–2010, but primarily 2003–2008, to map ice elevation change and infer mass changes for 33 glacier basins covering the mainland and most large islands in the nAP. Rates of ice volume and ice mass change are 27.7± 8.6 km3 a−1 and 24.9± 7.8 Gt a−1, equal to −0.73 m a−1 w.e. for the study area. Mass loss is the highest for eastern glaciers affected by major ice shelf collapses in 1995 and 2002, where twelve glaciers account for 60% of the total imbalance. However, losses at smaller rates occur throughout the nAP, at both high and low elevation, despite increased snow accumulation along the western coast and ridge crest. We interpret the widespread mass loss to be driven by decades of ice front retreats on both sides of the nAP, and extended throughout the ice sheet due to the propagation of kinematic waves triggered at the fronts into the interior.

Sign in / Sign up

Export Citation Format

Share Document