The east Antarctic ice: from ice sheet flow to iceberg dissolution

• Main Author: Hamley, Trevor Colin
• Format: Master Thesis
• Language: English
• Published: 1987
• Subjects: ice sheets; icebergs; Antarctica; Antarctic; East Antarctic Ice Sheet; Antarc*; Ice Sheet; Iceberg*
• Online Access: http://hdl.handle.net/11343/36575

© 1987 Trevor Colin Hamley This thesis investigates the question of the state of balance, mass budget and dynamics of a large section of the East Antarctic Ice Sheet. The distribution and dissolution of icebergs originating from the icesheet outflux is also determined. Comparison of field measurements collected from oversnow traversing, with balance calculations determined by computer modelling studies, shows that the ice sheet is not likely to be significantly out of balance (i.e. by more than ±10%). By assuming that it is in balance, the ratio of average column velocity to surface velocity is determined to be 0.89. Analysis of the mean strain-rate versus down slope shear-stress indicates values of the commonly used power flow law parameters to be n = 3.2 and k1 = 0.023 bar -n s-1. For the basal ice and high shear zone ice the value of k1 is shown to be k1 = 0.055 bar -n s-1. Comparison of the same results with laboratory work suggests temperatures of the basal ice to be between -5° C and -10° C. The outflux of ice between longitude 90° E and 150° E is estimated to be be 389 km3a-1. Analysis of iceberg size frequency distributions from shipboard observations reveals that Antarctic icebergs (less than 1000m in horizontal dimension) have a median life before breakage, of 0.2 years. This is significantly lower than previously thought. The mean melt rate is estimated to be 0.12 md-1 which agrees broadly with previous laboratory studies for water temperatures averaging + 1°C. More accurate data on iceberg calving, movement and dissolution is required to adequately assess discrepencies from balance computed by ice sheet accumulation and flow studies.