An Oceanographic Study of the Cavity Beneath the McMurdo Ice Shelf, Antarctica

• Main Author: Robinson, Natalie J
• Format: Thesis
• Language: unknown
• Published: 2004
• Subjects: Physical Geography and Environmental Geoscience not elsewhere classified; Current flow; Ocean circulation; Circulation patterns; Sediment deposition; School: School of Geography; Environment and Earth Sciences; 040699 Physical Geography and Environmental Geoscience not elsewhere classified; Marsden: 260403 Physical Oceanography; Degree Discipline: Geophysics; Degree Level: Masters; Degree Name: Master of Science; Marsden; McMurdo Ice Shelf; McMurdo Sound; Ross Island; Antarc*; Antarctica; Ice Shelf; Sea ice
• Online Access: https://doi.org/10.26686/wgtn.16920532.v1; https://figshare.com/articles/thesis/An_Oceanographic_Study_of_the_Cavity_Beneath_the_McMurdo_Ice_Shelf_Antarctica/16920532

This thesis reports the first observations of currents, temperature and salinity beneaththe McMurdo Ice Shelf, Antarctica. They are reviewed and discussed here in conjunctionwith results of a numerical modelling study used to simulate current flow and to investigatelocal sediment deposition. The McMurdo Ice Shelf lies behind Ross Island off theVictoria Land coast of Antarctica, and represents the northwest corner of the much largerRoss Ice Shelf. The site will be drilled by the ANDRILL consortium in 2006, passingthrough the ice shelf, the water column, and 1000 m into the sea floor, to obtain a recordof ice shelf and climate history in this area. This study stems from a site survey carried out in early 2003, for which access holeswere melted at two locations on the McMurdo Ice Shelf. Current meters surveyed multipledepths simultaneously during spring tides, and profiles of temperature and salinitywere collected through a diurnal tidal cycle at each site. Maximum currents were recordedin the boundary layer at the base of the ice shelf, reaching 0.22 m s−1 during the flood tide. The salinity and temperature profiles were similar at the two sites, with greater temporalvariability observed at the site closer to the open water of McMurdo Sound. Supercooling,due to the pressure-dependence of the in-situ freezing temperature, was observed at oneof the sites. At the second site, where the draft of the ice shelf was deeper, temperaturescorresponding to basal melting were observed. At a third site on the sea ice at the northwestern edge of the McMurdo Ice Shelf, acurrent meter surveyed the water column to 320 metres below sea level for 23 days. Thisallowed comparison of current behaviour through spring and neap tides, and between subseaice and sub-ice shelf environments in the same season. Net throughflow over springtides at each of the three sites was consistent with transport eastwards from McMurdoSound along the channel defined by local bathymetry. Profiles of temperature and salinityfrom beneath the ice shelf were ...