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  • International Polar Year (2007-2008); IPY  (2)
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  • 1
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    Ice velocities of Nordenskiöldbreen glacier, Svalbard (2010)
    PANGAEA
    In:  Supplement to: den Ouden, M A G; Reijmer, Carleen H; Pohjola, Veijo A; van de Wal, Roderik S W; Oerlemans, Johannes; Boot, Wim (2010): Stand-alone single-frequency GPS ice velocity observations on Nordenskiöldbreen, Svalbard. The Cryosphere, 4(4), 593-604, https://doi.org/10.5194/tc-4-593-2010
    Details
    Publication Date: 2023-12-13
    Description: Precise measurements of ice-flow velocities are necessary for a proper understanding of the dynamics of glaciers and their response to climate change. We use stand-alone single-frequency GPS receivers for this purpose. They are designed to operate unattended for 1-3 years, allowing uninterrupted measurements for long periods with hourly temporal resolution. We present the system and illustrate its functioning using data from 9 GPS receivers deployed on Nordenskiöldbreen, Svalbard, for the period 2006-2009. The accuracy of the receivers is 1.62 m based on the standard deviation in the average location of a stationary reference station (NBRef). Both the location of NBRef and the observed flow velocities agree within one standard deviation with DGPS measurements. Periodicity (6, 8, 12, 24 h) in the NBRef data is largely explained by the atmospheric, mainly ionospheric, influence on the GPS signal. A (weighed) running-average on the observed locations significantly reduces the standard deviation and removes high frequency periodicities, but also reduces the temporal resolution. Results show annual average velocities varying between 40 and 55 m/yr at stations on the central flow-line. On weekly to monthly time-scales we observe a peak in the flow velocities (from 60 to 90 m/yr) at the beginning of July related to increased melt-rates. No significant lag is observed between the timing of the maximum speed between different stations. This is likely due to the limited temporal resolution after averaging in combination with the relatively small distance (max. ±13 km) between the stations.
    Keywords: International Polar Year (2007-2008); IPY
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
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    DATA PANGAEA
  • 2
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    Mean chemical characteristics and volcano signatures of ice cores from Belukha, the Everest and three Svalbard sites (2012)
    PANGAEA
    In:  Supplement to: Moore, John C; Beaudon, Emilie; Kang, Shichang; Divine, Dmitry V; Isaksson, Elisabeth; Pohjola, Veijo A; van de Wal, Roderik S W (2012): Statistical extraction of volcanic sulphate from nonpolar ice cores. Journal of Geophysical Research, 117(D3), D03306, https://doi.org/10.1029/2011JD016592
    Details
    Publication Date: 2023-12-13
    Description: Ice cores from outside the Greenland and Antarctic ice sheets are difficult to date because of seasonal melting and multiple sources (terrestrial, marine, biogenic and anthropogenic) of sulfates deposited onto the ice. Here we present a method of volcanic sulfate extraction that relies on fitting sulfate profiles to other ion species measured along the cores in moving windows in log space. We verify the method with a well dated section of the Belukha ice core from central Eurasia. There are excellent matches to volcanoes in the preindustrial, and clear extraction of volcanic peaks in the post-1940 period when a simple method based on calcium as a proxy for terrestrial sulfate fails due to anthropogenic sulfate deposition. We then attempt to use the same statistical scheme to locate volcanic sulfate horizons within three ice cores from Svalbard and a core from Mount Everest. Volcanic sulfate is 〈5% of the sulfate budget in every core, and differences in eruption signals extracted reflect the large differences in environment between western, northern and central regions of Svalbard. The Lomonosovfonna and Vestfonna cores span about the last 1000 years, with good extraction of volcanic signals, while Holtedahlfonna which extends to about AD1700 appears to lack a clear record. The Mount Everest core allows clean volcanic signal extraction and the core extends back to about AD700, slightly older than a previous flow model has suggested. The method may thus be used to extract historical volcanic records from a more diverse geographical range than hitherto.
    Keywords: International Polar Year (2007-2008); IPY
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
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