The depth, motion and mass balance of the McMurdo Ice Shelf, Antarctica

An examination of the McMurdo Ice Shelf processes was carried out over two field seasons, 2003-2005. Measurements of surface ice motion and mass balance were made by placing stakes across the McMurdo Ice Shelf (from the accumulation area in Windless Bight to the Koettlitz Glacier in the ablation area) and measuring the movement of the ice by GPS (at a total of 52 stakes in the 03/04 seasons and 59 stakes in the 04/05 season resurveyed from the previous season). Ablation and accumulation rates were determined by measuring the distance from the top of the stake to the ice shelf surface on each visit. Ice depth was measured with two different ground penetrating radar systems (GPR). Depths ranged from 6m in the lower parts of the Koettlitz Glacier to ~100m close to Scott Base to a maximum of >300m in Windless Bight. Velocities ranged from <10 m/yr around Bratina Island to >160 m/yr close to the transition zone with the Ross Ice Shelf. In addition to depth surveys, common midpoint surveys were conducted at three locations in the accumulation area to establish the velocity of the transmitted radar waves through the ice. Ice shelf surface debris was sampled/collected for lab analysis to indicate debris provenance, debris transport history and the nature of debris modification during transport by the ice shelf. Ice samples were collected for isotopic analysis and a number of shell samples were collected from the ice surface for 14C dating.