Climate change and sea level: ice-dynamics and mass-balance studies on the Greenland ice sheet

• Main Authors: Huybrechts, Philippe, Mayer, Christoph, Oerter, Hans, Jung-Rothenhäusler, F.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 1999
• Subjects: glacier; Greenland; Ice Sheet; Ice Shelf; Nioghalvfjerdsfjorden; Sea ice
• Online Access: https://epic.awi.de/id/eprint/3663/; https://epic.awi.de/id/eprint/3663/1/Huy1999b.pdf; https://hdl.handle.net/10013/epic.14240; https://hdl.handle.net/10013/epic.14240.d001

Summary of the work packages perfomed by AWI:(1) Field work on Nioghalvfjerdsfjorden glacier:The AWI glaciology group joined the Danish glaciologists working on the floating tongue of Nioghalvfjerdsfjorden Glacier during thesummers of 1997 and 1998. The emphasis was on (i) seismic measurements to derive ice thickness and water depth below the ice shelf,(ii) tilt meter measurements at the margin, (iii) CTD profiling underneath the glacier and the sea ice, and (iv) GPS measurements. Themeasurements revealed a strong ice thickness gradient near to the grounding line, the existence of a large cavity below the ice shelf , andthe existence of a thick fresh water layer near to the ice front. These observations support the large basal melting rates below the ice shelfrevealed by the Danish field work. It is postulated that relatively warm oceanic water which enters the cavity through Dijmpna Sundprovides the energy for melting.(2) Observations on Storstroemmen glacier:Stakes planted on Storstroemmen in 1995 were revisited at the end of the summer season of 1997. Only three stakes were still standing.Velocity determinations revealed that the overall flow pattern is still governed by post-surge behaviour.(3) Flowline model studies:A flowline model was developed for the lower section of the Nioghalvfjerdsfjorden flowline. This line was embedded in a 3-D model ofthe entire Greenland ice sheet which provided the boundary conditions at the upper end of the section. Input parameters were provided bythe recent field data collected on the glacier. First results showed that the flowline model is able to produce quite realistic results and thatthe coupling did not introduce unwanted numerical effects or discontinuities. The meltrates required below the ice shelf to fit the modelledgeometry to the seismic measurements match very well with the field observations.(4) 3-D model studies:A 3-D thermomechanical ice-sheet model was used to refine estimates of the past, present, and future contribution of the Greenland icesheet to global ...