A correct interpretation of climatic records from deep ice cores requires detailed modeling of the ice-dynamical evolution around the drill site. This is necessary to determine the history of such crucial parameters as surface elevation, flow pattern, strain rates, basal temperature, and others, over the total period covered by the ice core. In addition, such modeling provides the age-depth profile and the location of the origin of the ice. We focus on a 600 x 400 km area around the EPICA drill site in Dronning Maud land and have nested a higher-order ice-flow model within a large-scale three-dimensional time-dependent ice sheet model of the Antarctic ice sheet. The large-scale model is based on the shallow ice approximation, considers coupling with an ice shelf and a variable grounding-line, and is implemented on a 20 km grid. The local model includes all stress gradients in the force balance and makes use of the most recent ice-thickness and accumulation data provided on a 2.5 km grid. The nested model is run through the last 4 glacial cycles. We use the coupled model to reconstruct the strain and thermal history over the total area where EDML ice originated in order to assess the risk of distortions in the stratigraphy and the potential ice loss by basal melting. The dating of the EDML ice core is performed by Lagrangian backtracing. The method relies on consecutive cubic spline interpolation of a particle's location using the reversed 3D velocity field obtained from forward experiments. An important output of the calculation is the palaeo-location at the origin of individual particle paths. This information is needed to assess the bias introduced by flow effects, which needs to be separated from the ice core records to extract the climatic information. The poster will summarize the main results of the modeling experiments.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL1-Processes and interactions in the polar climate system
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL6-Earth climate variability since the Pliocene