| The full history of ice sheet and climate interactions is recorded in the vertical profiles
of isotopic and other geochemical tracers in polar ice sheets. In addition, recent
advances in radiostratigraphy uncover the englacial layering that contains information
of past surface topographies and thus ice sheet volumes and sea level. Numerical
simulations of these archives could afford great advances both in the interpretation of
paleoclimatic tracers as well as to help improve ice sheet models themselves and
future projections. However, fundamental mathematical shortcomings in existing
ice sheet models subject tracers to spurious diffusion that renders such attempts
unfeasible.
Here, we propose a new vertical discretization for ice sheet models that eliminates numerical
diffusion entirely. Vertical motion through the model mesh is avoided by mimicking the
real-world ice flow as a thinning of underlying layers. Simulations of the last glacial cycle are
presented that show good skill in reproducing the reconstructed profile of the oxygen isotopic
ratio (δ18O) and the age scale (http://www.climate.unibe.ch/~born/ice_model.html). |