Session: Benchmarking & cross-cutting Group 1 (Isotope modelling, COMPARE)
Author: Martin Werner / email@example.com / Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
Co-author: Paul Gierz, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research;
Gregor Knorr, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research;
Xu Zhang, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research;
Gerrit Lohmann, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research;
Atmospheric and oceanic general circulation models (GCMs) enhanced by the capability to explicitly simulate the hydrological cycle of the two stable water isotopes H218O and HDO can provide an improved understanding regarding changes of the water isotope signals in various paleoclimate archives. However, so far the number of fully coupled atmosphere-ocean GCMs with explicit water isotope diagnostics is very limited. Such coupled models are required for a more comprehensive simulation of both past climates as well as related isotope changes in the Earth’s hydrological cycle.
Here, we report results of a set of paleoclimate simulations performed with the ECHAM5/MPI-OM model, enhanced by explicit water isotope diagnostics. The set of simulations include the PMIP target periods of the Last Millennium, the Mid-Holocene, the Last Glacial Maximum, the Last Interglacial, as well as a series of freshwater hosing experiments, mimicking past Heinrich events. In our model analyses we focus on the relation between spatial and temporal changes of water isotopes and key climate variables, e.g. land and ocean surface temperatures, precipitation amounts, and oceanic salinity. First results indicate that the spatial relation between the isotopic composition of precipitation and surface temperatures in mid- to high-latitudinal regions has remained rather constant over time, while temporal isotope-temperature relations have varied more strongly. Based on these analyses we explore how the explicit simulation of water isotopes within GCMs may contribute to an improved data-model comparison and understanding of past climate changes within the future framework of PMIP.