Outcome – University of Copenhagen


New Insights, results and new tools

Flow and behavior of ice streams have been identified as knowledge gaps, and most of the proposed research is thus explicitly directed towards new insight. The EGRIP ice-core project (with Danish logistics support from the A.P. Møller Foundation) represents the first attempt to obtain a deep ice-core through an ice stream. Development of instruments to observe ice crystal size and orientation in collaboration with researchers from AWI will provide new and improved tools to observe the ‘building blocks’ of ice deformation, the ice crystals. Ice fabrics may play a key role in understanding ice flow, we will gain new insight from a continuous mapping of crystal size as opposed to the situation in earlier projects, where only a small number of non-continuous measurements were made from thin ice sections.,

The inclusion of UWB surface radar allows us to expand the knowledge gained at the drill site to the surrounding area. The radar will be the first of next-generation radars with the capacity to image the ice base over an entire swath and map internal layers with fine resolution from the surface to the base. The radar will allow for very-high-resolution observations of deformation processes at EGRIP, the shear margins of the ice stream, and the basal structures. Ever since the basal structures were first observed in the RES layers, it has been a mystery how such structures form and whether they consist of buckling hard basal layers of ice from interglacial climate periods or of refrozen basal water. To supplement the radar measurements, drones will be applied to map very small surface-elevation variations and give new insights into how the ice is flowing in and around the structures. Finally, our chance to use the just-being-developed RADIX rapid access drill for these studies provides a unique opportunity to reveal what the basal structures are by stable water isotope measurements of the recovered ice cuttings.

The ice-deformation and flow models to be developed will give new insights into the ice-stream processes, which we will make available to the international ice-modelling community. We have started the development of anisotropic ice-flow models based on an assumption of vertical symmetry, because the ice crystals have a dominant orientation with vertical symmetry. The flow-law parameters are determined from the ice-crystal structure and calibrated by the borehole deformation data also using more detailed single-ice-crystal deformation models. We will attempt to constrain the memory-dependent behavior from deformation tests, from simulations of the conditions under which they developed at the drill site, and from models.