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. The Amery Ice Shelf (AIS), East Antarctica, has a layeredstructure, due to the presence of both meteoric and marine ice. In thisstudy, the thermal structure of the AIS and its spatial pattern areevaluated and analysed through borehole observations and numericalsimulations with Elmer/Ice, a full-Stokes ice sheet/shelf model. In the areawith marine ice, a near-isothermal basal layer up to 120 m thick isobserved, which closely conforms to the pressure-dependent freezingtemperature of seawater. In the area experiencing basal melting, largetemperature gradients, up to −0.36 ∘C m−1, are observed at thebase. Three-dimensional (3-D) steady-state temperature simulations with fourdifferent basal mass balance (BMB) datasets for the AIS reveal a highsensitivity of ice shelf thermal structure to the distribution of BMB. Wealso construct a one-dimensional (1-D) transient temperature column model tosimulate the process of an ice column moving along a flowline withcorresponding boundary conditions, which achieves slightly better agreementwith borehole observations than the 3-D simulations. Our simulations revealinternal cold ice advected from higher elevations by the AIS's main inletglaciers, warming downstream along the ice flow, and we suggest the thermalstructures dominated by these cold cores may commonly exist among Antarcticice shelves. For the marine ice, the porous structure of its lower layer andinteractions with ocean below determine the local thermal regime and giverise to the near-isothermal phenomenon. The limitations in our simulationsidentify the need for ice shelf–ocean coupled models with improvedthermodynamics and more comprehensive boundary conditions. Given thetemperature dependence of ice rheology, the depth-averaged ice stiffnessfactor B(T′)‾ derived from the most realistic simulatedtemperature field is presented to quantify the influence of the temperaturedistribution on ice shelf dynamics. The full 3-D temperature field providesa useful input to future modelling studies.

Thermal structure of the Amery Ice Shelf from borehole observations and simulations