TY - GEN A1 - Stober, Manfred A1 - Hitziger, Thomas A1 - Heim, Johanna A1 - Näke, Luisa A1 - Hepperle, Jörg T1 - Thirty years (1991 to 2021) ice elevation changes at Swiss Camp (West Greenland) T2 - Polar Regions, Climate Change and Society, 28th International Polar Conference, Potsdam, 01 – 05 May 2022, German Society for Polar Research N2 - Since 1991 a long-term project exists for investigation of ice elevation change, ice flow velocity and deformation.at Swiss Camp (West Greenland, inland ice, 80 km from Ilulissat). The site was measured by the author with precise geodetic GNSS measurements on ground since 1991 until 2014 by 12 campaigns, and studied in relation to climatic indicators. In spring 2012 an expedition of the HEIM group traversed the Greenlandic inland ice from East to West. They conducted GNSS measurements along their entire route in order to continue the former measurements of KORTH 2002 and later by HITZIGER. Motivated by the author the HEIM expedition could also re-measure completely the research area at Swiss Camp in end of May 2021. Here we report about the results in context of former campaigns. The 2021 GNSS measurements were performed by a Trimble R12 receiver mounted on a sledge which was transported over the snow surface to the old stake positions. Together with kinematical measurements of all path ways the current heights were used to determine the elevation changes by digital elevation models and 48 single point comparisons. Together with the old results from 1991 to 2014 by the author the current elevation changes now result in a unique long-term 30-year time series of elevation changes from precise geodetic ground measurements on the Greenlandic ice sheet. During the overall observation period from 1991 to 2021 the ice height decreased by 19.3 meter. The new results show that in the period from 2014 to 2015 until 2021 the ice height is still distinctly decreasing, but less than 2006 to 2014. The peak was reached in 2011-2014 with 1,4 m/year. Since 2014 to 2021 the decrease in height was 0.9 m/year on average. These results are discussed together with climatic indicators. Air temperature and pdd-values correlate well with these elevation changes and show lower melting rates in this period. This is agreeing with mass balance results from satellite observations (GRACE resp. GRACE-FO). So the locally derived height changes from geodetic ground measurements confirm the large-scale satellite results. KW - West Greenland KW - GNSS KW - measurements KW - HEIM expedition Y1 - 2022 U6 - https://doi.org/10.57738/BzPM_0762_2022 SN - 1866-3192 SP - S. 145 PB - Alfred-Wegener-Institut für Polar- und Meeresforschung CY - Bremerhaven ER - TY - GEN A1 - Näke, Luisa A1 - Hitziger, Thomas A1 - Heim, Johanna T1 - Ice elevation change based on GNSS measurements along the Greenland Korth Expedition T2 - Polar- und Meeresforschung, Polar Regions, Climate Change and Society 28th International Polar Conference Potsdam, 01 – 05 May 2022 German Society for Polar Research N2 - Since 2002, repetitive measurements have been taken on the southern Greenland ice sheet to study the change in ice elevation along a historical route defined by Alfred de Quervain. Until 2012, static GNSS measurements were carried out every 20 km under the responsibility of Wilfried Korth (Greenland Korth Expedition GKE). Since 2015, kinematic GNSS measurements have been recorded every second along the entire traverse from the East (near Tasiilaq) to the West (near Ilulissat). The kinematic repeat measurement took place in summer 2020, but it had to be ended prematurely and therefore the area of influence of Jakobshavn Isbræ could not be examined. Two comparison methods were used. On the one hand that of the crossing points and on the other hand that of the minimum distances. Both methods give similar results for the Greenland ice sheet. Another expedition took place in spring 2021, which kinematically measured the entire traverse. Based on this data, an estimate for the missing area from 2020 can be made and thus the comparability to the previous campaigns at the same season can be established. Likewise, the change in winter from the end of the thaw period to the beginning of it can be examined. Along the traverse, the influence of the two outlet glaciers Helheim in the East and Jakobshavn Isbræ in the West on the change in elevation is significant. In the accumulation area, a maximum gain of 2.1 m is recorded, whereas in the ablation area, a loss of up to 38.7 m occurs in the period from 2002 to 2021. KW - GNSS KW - Ice Sheet KW - Alfred de Quervain KW - measurement KW - Jakobshavn Isbræ KW - Wilfried Korth Y1 - 2022 U6 - https://doi.org/https://doi.org/10.57738/BzPM_0762_2022 SN - 1866-3192 SP - S. 107 PB - Alfred-Wegener-Institut für Polar- und Meeresforschung CY - Bremerhaven ER - TY - GEN A1 - Stober, Manfred A1 - Hitziger, Thomas A1 - Näke, Luisa A1 - Heim, Johanna A1 - Hepperle, Jörg T1 - Dreißig Jahre Eishöhenänderungen am Swiss Camp (Grönland) T2 - Polarforschung N2 - Seit 1991 betreibt der Erstautor ein Projekt zur Untersuchung der Eishöhenänderung, Fließgeschwindigkeit und Deformation mittels GNSS Bodenmessungen am Swiss Camp in der Nähe der Gleichgewichtslinie im westlichen Randbereich des Grönländischen Inlandeises. Die bisherigen Daten stammen aus 12 Kampagnen im Zeitraum 1991 bis 2014, also im Durchschnitt alle zwei Jahre. Neuerdings haben im Rahmen des Projektes „Spurensuche“ verschiedene Gruppen mit Schlitten das Grönländische Inlandeis von Ost nach West überquert und dabei auch die Oberflächenhöhen bestimmt. In den Jahren 2015 und 2021 konnte auch das Gebiet Swiss Camp mit GNSS vermessen werden. Mit deren Ergebnissen konnten nun die Höhenänderungen auf nunmehr 30 Jahre ausgedehnt werden und stellen somit ein einmaliges Langzeitprojekt dar Vor 2014 ergab sich eine stark beschleunigte Höhenabnahme. Auch die Höhenänderungen seit 2014 bis 2021 zeigen weiterhin eine deutliche Höhenabnahme, jedoch weniger schnell als in den Jahren zuvor. Diese zeitlichen Variationen der Höhenabnahmeraten stehen im Zusammenhang mit der Lufttemperatur im Sommer, die bis etwa 2012 einem ansteigenden Trend folgte, um in den anschließenden Jahren auf etwas niedrigerem Niveau zu bleiben. Ebenso war die Albedo in den Sommermonaten nach 2012 etwas höher als zuvor, so dass beide Effekte für geringere Schmelzenergie gesorgt haben. Diese lokalen Höhenänderungen stimmen überein mit großräumigen Befunden in ganz Grönland, die mit Schwerefelddaten der satellitengestützten Mission GRACE abgeleitet wurden. Insgesamt hat in den 30 Jahren die Eisoberfläche am Swiss Camp um etwa 20 m abgenommen, das sind ca. 1.7 % der dortigen Eismächtigkeit. Y1 - 2023 UR - https://polf.copernicus.org/articles/91/95/2023/polf-91-95-2023.html U6 - https://doi.org/10.5194/polf-91-95-2023 SN - 2190-1090 VL - 91 SP - 95 EP - 104 ER -