Utility of CryoSat-2 data for locating the ice sheet grounding line and determining ice shelf thickness: Final outcomes of the ESA STSE GLITter project

• Main Authors: Hogg, A., Shepherd, A., Nagler, T., Gilbert, L., Wuite, J., Muir, A., Corr, H., Steinhage, Daniel, Helm, Veit, Rott, H., Drinkwater, M.
• Format: Conference Object
• Language: unknown
• Published: 2016
• Subjects: Amundsen Sea; Ekström Ice Shelf; Ronne Ice Shelf; Antarc*; Antarctica; Filchner Ronne Ice Shelf; Filchner-Ronne Ice Shelf; Ice Sheet; Ice Shelf
• Online Access: https://epic.awi.de/id/eprint/41449/; https://hdl.handle.net/10013/epic.48369

Surface elevation measurements from CryoSat-2 data were examined to determine their utility for measuring ice sheet grounding line locations and ice thickness in Antarctica. The boundary between grounded and floating ice is an important glaciological parameter, because it delineates the lateral extent of an ice sheet and it marks the optimal location for computing ice discharge. We present a method for detecting the grounding line as the break in ice sheet surface slope, computed from CryoSat-2 elevation measurements using a plane-fitting solution. Furthermore we measure ice thickness at the grounding line using firn corrected CryoSat-2 data based on the theory of hydrostatic equilibrium. We apply these techniques to map the break in surface slope and ice shelf thickness at the grounding line in four topographically diverse sectors of Antarctica - the Filchner-Ronne ice shelf, the Ekström ice shelf, the Amundsen Sea Sector, and the Larsen-C ice shelf - using CryoSat-2 observations acquired between July 2010 and May 2014. An inter-comparison of the CryoSat-2 break in surface slope with independent measurements of the hinge line position determined from quadruple-difference synthetic aperture radar interferometry (QDInSAR) shows good overall agreement, with a mean separation of 4.5 km. In the Amundsen Sea Sector, where in places over 35 km of hinge line retreat has occurred since 1992. The CryoSat-2 break in surface slope coincides with the most recent hinge line position, recorded in 2011. Ice shelf ice thickness measurements are validated with Radio Echo Sounding (RES) point data and show good overall agreement with BEDMAP 2 ice thickness data. The techniques we have developed are automatic, computationally-efficient, and can be repeated in the future given further data acquisitions offering a complimentary approach to existing techniques.