Characteristics of the Ross and Southern McMurdo ice shelves as revealed from ground-based radar surveys.

• Main Author: Ryan, Michelle R.
• Format: Other/Unknown Material
• Language: English
• Published: University of Canterbury 2016
• Subjects: Antarctic; McMurdo Ice Shelf; Ross Ice Shelf; The Antarctic; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: http://hdl.handle.net/10092/13464; https://doi.org/10.26021/6284

Ice shelves are an important component of the Antarctic Ice Sheet as they indirectly control sea level rise by regulating mass flux into the ocean. The coupling of ice shelves with the ocean and the atmosphere makes them vulnerable to climate change. With the oceans absorbing most of the energy from global warming, there is an increased interest in understanding ice-ocean interactions. Basal processes are poorly understood as the base of an ice shelf is difficult to measure due to its inaccessibility. This thesis explores the effect different internal and basal processes have on ice shelves, and their implications for ice shelf stability, using ground penetrating radar (GPR) and a new phase sensitive radar (ApRES). To achieve this, two study sites were visited. A GPR survey was made on the northern grounding line of the stationary Southern McMurdo Ice Shelf (SMIS) in November 2014 to examine deformation of internal layers, measure ice thickness distribution across a grounding zone, and interpret basal topography. In November 2015, 21 sites in the central Ross Ice Shelf (RIS) were measured with ApRES to estimate the distribution and thickness of marine ice, vertical strain and basal melting/freezing. Ice thickness of the northern SMIS grounding zone is mapped to high resolution and with an uncertainty of <10 m. Ice is thickest near the grounding line (≈250 m) and thins to 200 m within 3 km seaward of the coast. Basal topography and deformation of internal layers reveal basal processes and interactions of the ice shelf with the ocean. Basal crevasses at the grounding line complicate the radar profile and are created as a result of tidal rather than shear stresses. Downwarping and truncation of internal layers just seaward of the grounding line are caused by basal melting. The generated meltwater directly influences basal topography creating stepped features in the ice shelf base which persist for kilometres from the grounding line. Widespread marine ice at the base of the RIS is revealed by ApRES point ...