RTopo-2: A global dataset of ice sheet topography, cavity geometry and ocean bathymetry to study ice-ocean interaction in Northeast Greenland

• Main Authors: Schaffer, Janin, Timmermann, Ralph, Arndt, Jan Erik, Steinhage, Daniel, Kanzow, Torsten
• Format: Conference Object
• Language: unknown
• Published: 2014
• Subjects: Antarc*; Antarctica; glacier; Greenland; Ice Sheet; Ice Shelf; Ice Shelves; Nioghalvfjerdsfjorden; Sea ice
• Online Access: https://epic.awi.de/id/eprint/37733/; https://hdl.handle.net/10013/epic.45344

Mass loss from the Greenland Ice Sheet presently accounts for about 12% of the global mean sea-level rise. The ocean plays an important role in modulating the mass balance of the ice sheets in both polar regions by interacting with the ice shelves in Antarctica and with the marine-terminating outlet glaciers in Greenland. A key region for the latter is the floating ice tongue of Nioghalvfjerdsfjorden (’79.5°N Glacier’). To study the relevant processes here and to provide guidance for a large field campaign on and off the floating ice tongue in summer 2016, we plan to set up a global finite-element sea ice - ice shelf - ocean model with a mesh focussed on the Northeast Greenland shelf region and the sub-ice cavities. Given that the flux of warm water onto the shelf and into the sub-ice cavity is steered by complex bathymetry, a detailed topography dataset including the most recent surveys in the area is an essential ingredient. We follow the spirit of the global RTOPO-1 data set and compile consistent maps of global ocean bathymetry, upper and lower ice surface topographies and global surface height on a spherical grid with now 0.5 minute resolution. The maps include multibeam survey data for the bathymetry on the shelf off Northeast Greenland as well as high-resolution gridded data for upper and lower ice surface topography and cavity geometry of Nioghalvfjerdsfjorden going back to seismic surveys and to data from the IceBridge campaign. We show the improvements achieved in RTopo-2 for the region off Northeast Greenland in comparison with bathymetric products commonly used for numerical simulations. Based on the new data set we also discuss possible subsurface supply pathways of warm modified Atlantic waters onto the continental shelf off Northeast Greenland, possibly triggering basal melting in the subglacial cavities.