BIIR Cost Preview Preparatory Materials

BIIR Can Help Answer These Science Questions Refined science questions derived in part from the St. Petersburg ISMASS Meeting (July 2008) (in response to downselect review board) How can IPCC error bounds on the present mass balance of the polar ice sheet and their contribution to global sea level rise be reduced? – Ice thickness used to compute flux has not been systematically measured around the perimeter of the ice sheets. BIIR will conduct a circum-ice-sheet campaign to accurately measure ice thickness and refine flux estimates through combination with DESDYNI measurements of surface velocity. What causes observed, abrupt changes in ice sheet motion? Does a rapid change in a glacier always lead to a large change in the ice sheet volume? – Restraining forces limit the outward flow of ice. Changes in the longtitudinal, basal or lateral boundary conditions leads to a commensurate response in flow. BIIR will measure for the first time the 3-d dimensional physical properties of the surface and base of select glacier basins Information on 3-d basal topography and the distribution of basal water will be provided to modelers for estimating the present stress regime of the ice sheet and determining whether basal geometries support quasi-equilibrium configurations. How will the mass balance and dynamics of the ice sheets change in the future? – BIIR will produce 3-d maps of basal topography, and surface and basal reflectivity. BIIR will supplement ICEsat measurements of surface topography by providing information for interpolating between ICEsat ground tracks. The maps will be a primary input for predictive ice sheet dynamics models.

Basin Maps Selected basins for early, process oriented studies using BIIR

GISMO Lakes Result Upper Left: Radarsat winter scene. Upper Right: 150 MHz GISMO surface image Lower left: Radarsat summer scene Lower Right: GISMO image on top of Gismo topography (preliminary result in need of a tilt correction)

GISMO Basal Imagery 5x20 Km 3-d image of the base of the ice sheet. Scene is an orthorectified mosaic located just south of the main Jacobshavn Drainage Channel (to be corrected for cross track bias between mosaic swaths)