| Summary: | The three-dimensional ice-sheet model SIC OPOLIS is used to simulate the dynamic/thermodynamic behaviour of the entire Greenland ice sheet from 250000 a BP until today. External forcing consists of a surface-temperature history constructed from δ18O data of the GRIP core, a snowfall history coupled linearly to that of the surface temperature, a piecewise linear sea-level scenario and a constant geothermal heat flux. T he simulated Greenland ice sheet is investigated in the vicinity of Summit, the position where the maximum elevation is taken, and where the two drill sites GRIP and GISP2 are situated 28 km apart from each other. In this region, the agreement between modelled and observed topography and ice temperature turns out to be very good. Computed age- depth profiles for GRIP and GISP2 are presented, which can be used to complete the dating of these cores in the deeper regions where annual-layer counting is not possible. However, artificial diffusion influences the computed ages in a near-basal boundary layer of approximately 15 % of the ice thickness, so that the age at the bottom of the cores cannot be predicted yet.
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