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  • 1
    Online Resource
    Online Resource
    American Geophysical Union (AGU) ; 2014
    In:  Geophysical Research Letters Vol. 41, No. 22 ( 2014-11-28), p. 8123-8129
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 41, No. 22 ( 2014-11-28), p. 8123-8129
    Abstract: Volume change 2011–2013 of Antarctic Peninsula glaciers based on new technique Downwasting of most outlet glaciers ongoing 18 years after Larsen‐A collapse Trend of decrease in ice mass losses due to deceleration of glacier flow
    Type of Medium: Online Resource
    ISSN: 0094-8276 , 1944-8007
    URL: Issue
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2014
    detail.hit.zdb_id: 2021599-X
    detail.hit.zdb_id: 7403-2
    SSG: 16,13
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  • 2
    In: The Cryosphere, Copernicus GmbH, Vol. 12, No. 4 ( 2018-04-11), p. 1273-1291
    Abstract: Abstract. We analysed volume change and mass balance of outlet glaciers on the northern Antarctic Peninsula over the periods 2011 to 2013 and 2013 to 2016, using high-resolution topographic data from the bistatic interferometric radar satellite mission TanDEM-X. Complementary to the geodetic method that applies DEM differencing, we computed the net mass balance of the main outlet glaciers using the mass budget method, accounting for the difference between the surface mass balance (SMB) and the discharge of ice into an ocean or ice shelf. The SMB values are based on output of the regional climate model RACMO version 2.3p2. To study glacier flow and retrieve ice discharge we generated time series of ice velocity from data from different satellite radar sensors, with radar images of the satellites TerraSAR-X and TanDEM-X as the main source. The study area comprises tributaries to the Larsen A, Larsen Inlet and Prince Gustav Channel embayments (region A), the glaciers calving into the Larsen B embayment (region B) and the glaciers draining into the remnant part of the Larsen B ice shelf in Scar Inlet (region C). The glaciers of region A, where the buttressing ice shelf disintegrated in 1995, and of region B (ice shelf break-up in 2002) show continuing losses in ice mass, with significant reduction of losses after 2013. The mass balance numbers for the grounded glacier area of region A are −3.98 ± 0.33 Gt a−1 from 2011 to 2013 and −2.38 ± 0.18 Gt a−1 from 2013 to 2016. The corresponding numbers for region B are −5.75 ± 0.45 and −2.32 ± 0.25 Gt a−1. The mass balance in region C during the two periods was slightly negative, at −0.54 ± 0.38 Gt a−1 and −0.58 ± 0.25 Gt a−1. The main share in the overall mass losses of the region was contributed by two glaciers: Drygalski Glacier contributing 61 % to the mass deficit of region A, and Hektoria and Green glaciers accounting for 67 % to the mass deficit of region B. Hektoria and Green glaciers accelerated significantly in 2010–2011, triggering elevation losses up to 19.5 m a−1 on the lower terminus during the period 2011 to 2013 and resulting in a mass balance of −3.88 Gt a−1. Slowdown of calving velocities and reduced calving fluxes in 2013 to 2016 coincided with years in which ice mélange and sea ice cover persisted in proglacial fjords and bays during summer.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 2393169-3
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  • 3
    Online Resource
    Online Resource
    American Geophysical Union (AGU) ; 2024
    In:  Journal of Geophysical Research: Earth Surface Vol. 129, No. 6 ( 2024-06)
    In: Journal of Geophysical Research: Earth Surface, American Geophysical Union (AGU), Vol. 129, No. 6 ( 2024-06)
    Abstract: Surface meltwater extent and sea‐ice‐modulated oceanic forcing act as statistically significant precursors to summertime ice‐flow acceleration in the Antarctic Peninsula Surface meltwater presence and enhanced ocean temperatures presage summertime acceleration with different temporal lead times A relationship exists between El Niño Southern Oscillation and Antarctic ice‐flow seasonality, with the unprecedented magnitude El Niño event of 2016 driving an anomalous wintertime speed‐up through enhanced local surface and oceanic forcing
    Type of Medium: Online Resource
    ISSN: 2169-9003 , 2169-9011
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2024
    detail.hit.zdb_id: 2130824-X
    detail.hit.zdb_id: 2138320-0
    SSG: 16,13
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  • 4
    In: Earth System Science Data, Copernicus GmbH, Vol. 14, No. 9 ( 2022-09-01), p. 3915-3945
    Abstract: Abstract. The European Space Agency SnowSAR instrument is a side-looking, dual-polarised (VV/VH), X/Ku band synthetic aperture radar (SAR), operable from various sizes of aircraft. Between 2010 and 2013, the instrument was deployed at several sites in Northern Finland, Austrian Alps and northern Canada. The purpose of the airborne campaigns was to measure the backscattering properties of snow-covered terrain to support the development of snow water equivalent retrieval techniques using SAR. SnowSAR was deployed in Sodankylä, Northern Finland, for a single flight mission in March 2011 and 12 missions at two sites (tundra and boreal forest) in the winter of 2011–2012. Over the Austrian Alps, three flight missions were performed between November 2012 and February 2013 over three sites located in different elevation zones representing a montane valley, Alpine tundra and a glacier environment. In Canada, a total of two missions were flown in March and April 2013 over sites in the Trail Valley Creek watershed, Northwest Territories, representative of the tundra snow regime. This paper introduces the airborne SAR data and coincident in situ information on land cover, vegetation and snow properties. To facilitate easy access to the data record, the datasets described here are deposited in a permanent data repository (https://doi.org/10.1594/PANGAEA.933255, Lemmetyinen et al., 2021).
    Type of Medium: Online Resource
    ISSN: 1866-3516
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2022
    detail.hit.zdb_id: 2475469-9
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  • 5
    Online Resource
    Online Resource
    Copernicus GmbH ; 2021
    In:  The Cryosphere Vol. 15, No. 9 ( 2021-09-13), p. 4399-4419
    In: The Cryosphere, Copernicus GmbH, Vol. 15, No. 9 ( 2021-09-13), p. 4399-4419
    Abstract: Abstract. Synthetic aperture radar interferometry (InSAR) is an efficient technique for mapping the surface elevation and its temporal change over glaciers and ice sheets. However, due to the penetration of the SAR signal into snow and ice, the apparent elevation in uncorrected InSAR digital elevation models (DEMs) is displaced versus the actual surface. We studied relations between interferometric radar signals and physical snow properties and tested procedures for correcting the elevation bias. The work is based on satellite and in situ data over Union Glacier in the Ellsworth Mountains, West Antarctica, including interferometric data of the TanDEM-X mission, topographic data from optical satellite sensors and field measurements on snow structure, and stratigraphy undertaken in December 2016. The study area comprises ice-free surfaces, bare ice, dry snow and firn with a variety of structural features related to local differences in wind exposure and snow accumulation. Time series of laser measurements of NASA's Ice, Cloud and land Elevation Satellite (ICESat) and ICESat-2 show steady-state surface topography. For area-wide elevation reference we use the Reference Elevation Model of Antarctica (REMA). The different elevation data are vertically co-registered on a blue ice area that is not affected by radar signal penetration. Backscatter simulations with a multilayer radiative transfer model show large variations for scattering of individual snow layers, but the vertical backscatter distribution can be approximated by an exponential function representing uniform absorption and scattering properties. We obtain estimates of the elevation bias by inverting the interferometric volume correlation coefficient (coherence), applying a uniform volume model for describing the vertical loss function. Whereas the mean values of the computed elevation bias and the elevation difference between the TanDEM-X DEMs and the REMA show good agreement, a trend towards overestimation of penetration is evident for heavily wind-exposed areas with low accumulation and towards underestimation for areas with higher accumulation rates. In both cases deviations from the uniform volume structure are the main reason. In the first case the dense sequence of horizontal structures related to internal wind crust, ice layers and density stratification causes increased scattering in near-surface layers. In the second case the small grain size of the top snow layers causes a downward shift in the scattering phase centre.
    Type of Medium: Online Resource
    ISSN: 1994-0424
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2393169-3
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