TY - GEN A1 - Korth, Wilfried A1 - Hitziger, Thomas A1 - Hofmann, Uwe A1 - Pavelka, Karel T1 - Monitoring of surface ice height changes in Greenland T2 - Polar Systems under Pressure: 27th International Polar Conference, Rostock, 25 - 29 March 2018 , German Society for Polar Research N2 - In 2002 a long term project for geodetic monitoring of heights and height changes was started. A series of six field campaigns was realized and the project is still running. In result there are precise surface height data available representative for a traverse between Isortoq (East Greenland) and Ilulissat (West Greenland). The measurements were carried out mainly by GNSS in static mode for points close to the camp sites and in kinematic mode for the full traverse since 2015. The data are showing an increasing of the glacier volume shrinking. Close to the rims of the ice cap in 2015 the lowering of the surface was nearly 150 % of the value of 2002. In the middle of the traverse where the height is about 2,500 m a surface rising of 0.15 m/a changed to a more or less stable surface in 2015. All together this leads to a significant speed up of the negative volume change. Results of satellite missions like GRACE are showing a negative but not increasing mass balance of the region which was investigated. This difference might be caused in refreezing of melting water within the upper snow layers. Therefore at some representative spots density profiles close to the surface were measured and compared to older data. The density data are changed to higher values close to the surface and one can find much more ice layers into the snow. This means that out of the blue ice areas above the equilibrium zone an interpretation of height changes is difficult. A direct link between height and mass is not possible or at least biased. Y1 - 2018 U6 - https://doi.org/10.2312/BzPM_0716_2018 SN - 1866-3192 SP - S. 103 PB - Alfred-Wegener-Inst. für Polar- und Meeresforschung CY - Bremerhaven ER - TY - GEN A1 - Stempfhuber, Werner A1 - Korth, Wilfried A1 - Hitziger, Thomas A1 - Hofmann, Uwe T1 - Glacier surface and mass balance variation in Alska ans Southern Greenland T2 - Polar Systems under Pressure: 27th International Polar Conference, Rostock, 25 - 29 March 2018 , German Society for Polar Research N2 - The Juneau Icefield Research Program (JIRP) in Alaska is a long-term glacier monitoring project with unique records in the area of biology, meteorology, resource and environmental studies, geology, geomorphology and geophysics, terrestrial photogrammetry, remote sensing and land surveying. The Juneau Icefield is one of several icefield regions and glaciated areas stretching from southern British Columbia to the Alaska Peninsula and across the Canada border with approximately 40 main- and 140 sub-glaciers. The first data sets have been recorded in the year 1946. Annual GNSS profile measurements over approximately 4.400 square kilometers have been measured since 1992. These unique records in combination with geotechnical data sets represent a detailed report of weather conditions in northern regions. A low cost based L1 GNSS monitoring will be installed in the next field session 2018 to determine glacier velocity and elevation. Terrestrial laser scanning and SfM-methodes will be used to supplement the terrasat X tandem DGM. The second glacier research region of our institute is Greenland. GNSS profiles from coast to coast have been observed over the last 15 years. The paper will describe similarities and differences of the total mass balance and global effects. Both glacier regions are indicating elevation changes related to temperature plus rain- or snowfall. Remote sensing datasets provide additional measurement result to discuss this research approach. KW - Greenland KW - Juneau Icefield Research Program (JIRP) KW - GNSS Y1 - 2018 U6 - https://doi.org/10.2312/BzPM_0716_2018 SN - 1866-3192 SP - S. 176 PB - Alfred-Wegener-Institut für Polar- und Meeresforschung CY - Bremerhaven ER -