Distribution of marine ice beneath the Amery Ice Shelf

We present a map of the marine ice accreted to the base of the Amery Ice Sh elf (AIS), East Antarctica. This map is obtained by converting a Digital El evation Model (DEM) of the AIS generated from satellite radar altimeter dat a to an ice thickness map, assuming hydrostatic equilibrium, and subtractin g from that a second ice thickness map, derived from airborne radio-echo so unding (RES) measurements. The RES signal does not penetrate the marine ice , so the measurement is only to the meteoric-marine ice boundary, and there fore the difference between the two maps is the marine ice thickness. The m arine ice is up to 190 m thick and accounts for about 9% of the shelf volum e. It is concentrated in the northwest of the shelf, a result of the clockw ise ocean circulation in the cavity below.