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  • 2015-2019  (86)
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  • 1
    Online Resource
    Online Resource
    [Bremerhaven] : [Alfred-Wegener-Institut für Polar- und Meeresforschung]
    Keywords: Forschungsbericht ; Polargebiete ; Satellitenfernerkundung ; Radarfernerkundung ; Satellitenaltimetrie
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (74 Seiten, 23,4 MB) , Diagramme, Karten
    Language: German
    Note: Förderkennzeichen BMBF 50EE1331. - Verbund-Nummer 01150613 , Paralleltitel dem englischen Berichtsblatt entnommen , Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden , Sprache der Zusammenfassung: Deutsch, Englisch
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  • 2
    Publication Date: 2015-11-20
    Print ISSN: 0022-1430
    Electronic ISSN: 1727-5652
    Topics: Geography , Geosciences
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  • 3
    Publication Date: 2023-03-16
    Keywords: Antarctica; AWI_Glac; Glaciology @ AWI
    Type: Dataset
    Format: application/x-netcdf, 12.8 MBytes
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  • 4
    Publication Date: 2023-03-16
    Keywords: Antarctica; AWI_Glac; DATE/TIME; Glaciology @ AWI; Ice thickness, glacier; LATITUDE; LONGITUDE
    Type: Dataset
    Format: text/tab-separated-values, 104080 data points
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  • 5
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    PANGAEA
    In:  Supplement to: Rückamp, Martin; Neckel, Niklas; Berger, Sophie; Humbert, Angelika; Helm, Veit (2019): Calving Induced Speedup of Petermann Glacier. Journal of Geophysical Research-Earth Surface, https://doi.org/10.1029/2018JF004775
    Publication Date: 2023-03-16
    Description: This study assesses the response on ice dynamics of Petermann Glacier, a major outlet glacier in northern Greenland, to the 2012 and a possible future calving event. So far Petermann Glacier has been believed to be dynamically stable as another large calving event in 2010 had no significant impact on flow velocity or grounding line retreat. By analyzing a time series of remotely sensed surface velocities, we find an average acceleration of 10% between winter 2011/2012 and winter 2016/2017. This increase in surface velocity is not linear but can be separated into two parts, starting in 2012 and 2016 respectively. By conducting modelling experiments, we show that the first speed-up can be directly connected to the 2012 calving event, while the second speed-up is not captured. However, on recent remote sensing imagery newly developing fractures are clearly visible ~12,km upstream from the terminus, propagating from the eastern fjord wall to the center of the ice tongue, indicating a possible future calving event. By including these fracture zones as a new terminus position in the modelling domain we are able to reproduce the second speed-up, suggesting that surface velocities remain on the 2016/2017 level after the anticipated calving event. This indicates that, from a dynamical point of view, the terminus region has already detached from the main ice tongue.
    Keywords: AWI_Glac; File format; File name; File size; Glaciology @ AWI; North Greenland; Petermann_Glacier; RADAR; Radar profile; Uniform resource locator/link to file
    Type: Dataset
    Format: text/tab-separated-values, 72 data points
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  • 6
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    PANGAEA
    In:  Supplement to: Humbert, Angelika; Steinhage, Daniel; Helm, Veit; Beyer, Sebastian; Kleiner, Thomas (2018): Missing Evidence of Widespread Subglacial Lakes at Recovery Glacier, Antarctica. Journal of Geophysical Research-Earth Surface, 123(11), 2802-2826, https://doi.org/10.1029/2017JF004591
    Publication Date: 2023-03-16
    Description: Recovery Glacier reaches far into the East Antarctic Ice Sheet. Recent projections point out that its dynamic behaviour has a considerable impact on future Antarctic ice loss (Golledge et al. 2017). Subglacial lakes are thought to play a major role in the initiation of the rapid ice flow (Bell et al. 2007). Satellite altimetry observations have even suggested several actively filling and draining subglacial lakes beneath the main trunk (Smith et al. 2009). We present new data of the geometry of this glacier and investigate its basal properties employing radio-echo sounding. Using ice-sheet modelling, we were able to constrain estimates of radar absorption in the ice, but uncertainties remain large. The magnitude of the basal reflection coefficient is thus still poorly known. However, its spatial variability, in conjunction with additional indicators, can be used to infer the presence of subglacial water. We find no clear evidence of water at most of the previously proposed lake sites. Especially locations where altimetry detected active lakes, do not exhibit lake characteristics in RES. We argue that lakes far upstream the main trunk are not triggering enhanced ice flow, which is also supported by modeled subglacial hydrology.
    Keywords: Antarctica; AWI_Glac; Glaciology @ AWI
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 7
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    PANGAEA
    In:  Supplement to: Obu, Jaroslav; Lantuit, Hugues; Grosse, Guido; Günther, Frank; Sachs, Torsten; Helm, Veit; Fritz, Michael (2017): Coastal erosion and mass wasting along the Canadian Beaufort Sea based on annual airborne LiDAR elevation data. Geomorphology, 293, 331-346, https://doi.org/10.1016/j.geomorph.2016.02.014
    Publication Date: 2023-01-13
    Description: LiDAR scanning of the Yukon Coast and Herschel Island took place during the AIRMETH (AIRborne studies of METHane emissions from Arctic wetlands) campaigns (Kohnert et al., 2014) on 10 July 2012 and on 22 July 2013. Point cloud data were acquired with a RIEGL LMSVQ580 laser scanner instrument on board the Alfred Wegener Institute's POLAR-5 science aircraft. The laser scanner was operated with a 60° scan angle at a flight height of around 200 m above ground in 2012 and 500 m in 2013. This resulted in a scan width from 200 (2012) to 500 m (2013) and a mean point-to-point distance of 0.5–1.0 m. During the flight on July 10, 2012 the weather was cloudy with a cloud base around 200 m.a.s.l. . Air temperature ranged between 10 and 12 °C with wind speed ranging from 15 to 19 km/h from easterly direction (70–90°). The last recorded storm was on June 17. During the scanning on July 22, 2013, the weather was nearly cloudless with air temperature 9 °C. Wind speed was 15 km/h from easterly direction (60–80°). The last storm before the acquisition occurred on July 2. Raw laser data were calibrated, combined with the post-processed GPS trajectory, corrected for altitude, and referenced to the EGM (Earth Gravitational Model) 2008 geoid (Pavlis et al., 2008). The final georeferenced point cloud data accuracy was determined to be better than 0.15 ± 0.1 m. The loss of accuracy varied along the flight track because of the vertical accuracy of the post-processed GPS trajectory. The GPS datawere acquired in 50Hz resolutionwith aNovatel OEM4 receiver on board POLAR-5. The GPS trajectory was post-processed using precise ephemerides and the commercial software package Waypoint 8.5 (PPP [precise point positioning] processing). For the interpolation to the final DEM an inverse distance weighting (IDW) algorithm was applied using all cloud points within a 10 m radius of each point. Finally, the DEMs from the different acquisition years were interpolated toraster grids of 1 m horizontal resolution in NAD83 UTM zone 7 coordinate system. To quantify vertical change that is significant at the 99% confidence interval, we used three times RMS error procedure by Jaw (2001). Vertical accuracies for both datasets were estimated to be 0.15 m, which results in the threshold of 0.64 m for significant vertical elevation change. The accuracy of the datasets was additionally tested at locations characterized by the presence of anthropogenic features that presumably remain stable and are not affected by vertical movements because of artificial embankments underneath them. The differences between both DEM datasets were assessed along profiles and were within the previously-stated 0.15 m uncertainty.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 8
    Publication Date: 2023-01-13
    Keywords: DATE/TIME; Event label; File name; File size; HER; Herschel_Island; Laser Scanner VQ580; Latitude of event; Longitude of event; Longitude of event 2; MULT; Multiple investigations; Uniform resource locator/link to file; Yukon_Coast; Yukon, Canada, North America
    Type: Dataset
    Format: text/tab-separated-values, 6 data points
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  • 9
    Publication Date: 2023-01-13
    Keywords: DATE/TIME; Event label; File name; File size; HER; Herschel_Island; Laser Scanner VQ580; Latitude of event; Latitude of event 2; Longitude of event; Longitude of event 2; MULT; Multiple investigations; Uniform resource locator/link to file; Yukon_Coast; Yukon, Canada, North America
    Type: Dataset
    Format: text/tab-separated-values, 6 data points
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  • 10
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    In:  Institut für Geographie, Friedrich-Alexander-Universität, Erlangen-Nürnberg | Supplement to: Seehaus, Thorsten; Marinsek, Sebastián; Helm, Veit; Skvarca, Pedro; Braun, Matthias Holger (2015): Changes in ice dynamics, elevation and mass discharge of Dinsmoor-Bombardier-Edgeworth glacier system, Antarctic Peninsula. Earth and Planetary Science Letters, 427, 125-135, https://doi.org/10.1016/j.epsl.2015.06.047
    Publication Date: 2023-10-28
    Description: The northern Antarctic Peninsula is one of the fastest changing regions on Earth. The disintegration of the Larsen-A Ice Shelf in 1995 caused tributary glaciers to adjust by speeding up, surface lowering, and overall increased ice-mass discharge. In this study, we investigate the temporal variation of these changes at the Dinsmoor-Bombardier-Edgeworth glacier system by analyzing dense time series from various spaceborne and airborne Earth observation missions. Precollapse ice shelf conditions and subsequent adjustments through 2014 were covered. Our results show a response of the glacier system some months after the breakup, reaching maximum surface velocities at the glacier front of up to 8.8 m/d in 1999 and a subsequent decrease to ~1.5 m/d in 2014. Using a dense time series of interferometrically derived TanDEM-X digital elevation models and photogrammetric data, an exponential function was fitted for the decrease in surface elevation. Elevation changes in areas below 1000 m a.s.l. amounted to at least 130±15 m130±15 m between 1995 and 2014, with change rates of ~3.15 m/a between 2003 and 2008. Current change rates (2010-2014) are in the range of 1.7 m/a. Mass imbalances were computed with different scenarios of boundary conditions. The most plausible results amount to -40.7±3.9 Gt-40.7±3.9 Gt. The contribution to sea level rise was estimated to be 18.8±1.8 Gt18.8±1.8 Gt, corresponding to a 0.052±0.005 mm0.052±0.005 mm sea level equivalent, for the period 1995-2014. Our analysis and scenario considerations revealed that major uncertainties still exist due to insufficiently accurate ice-thickness information. The second largest uncertainty in the computations was the glacier surface mass balance, which is still poorly known. Our time series analysis facilitates an improved comparison with GRACE data and as input to modeling of glacio-isostatic uplift in this region. The study contributed to a better understanding of how glacier systems adjust to ice shelf disintegration.
    Keywords: Antarctic Peninsula; Dinsm-Bombard-Edgew_gs; Dinsmoor-Bombardier-Edgeworth; MULT; Multiple investigations; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; SPP1158
    Type: Dataset
    Format: application/zip, 77.7 MBytes
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