Age and basal conditions using a 2.5D ice flow model constrained by radar horizons along the Dome Fuji–EDML flow line, Antarctica

Abstract. Ice flow modelling is important for understanding the factors that affect overall ice sheet dynamics. We apply a 2.5D inverse flow tube model to the flow line from Dome Fuji (DF) to the EPICA Dronning Maud Land (EDML) ice core site in East Antarctica. The model is constrained by eight continuous and five discontinuous internal reflecting horizons traced from radar surveys and dated by connecting them to the DF ice core. The flow tube was determined by following the steepest slope of surface elevation from EDML upstream to DF. The aim of this study is to estimate basal melt rates, accumulation rates, particle trajectories, the age of ice and the thinning function along the flow line and compare results to previous modelling and observation work.

We find that basal melting is highest where there are dips in the bedrock, whereas stagnant ice tends to occur on or slightly downstream of bedrock rises. The modelled accumulation rate generally increases with proximity to the coast, agreeing well with previous studies. Modelling particle trajectories gives us an understanding of the deposition location and therefore altitude and temperature, allowing measurements from the deepest and oldest ice in the EDML ice core to be corrected accordingly. Results show that the oldest ice from the EDML ice core may have come from up to 130 km upstream. This is significantly closer to the ice core site than previous estimates. Modelled surface velocity magnitudes around EDML match those found by observations. We also identify one area around 200 km from the DF summit, where the modelled maximum age of ice is >1 Ma.