HR: 0800h
AN: PP41B-0648 [Abstracts]
TI: Simulations of the Eemian interglacial and the subsequent glacial inception with an OAGCM driven by
orbitally-induced changes in insolation
AU: * Kaspar, F
EM: kaspar@dkrz.de
AF: Max-Planck-Institute for Meteorology, Model and Data Group, Bundesstr. 53, Hamburg, 20146
Germany
AU: * Kaspar, F
EM: kaspar@dkrz.de
AF: Institute for Meteorology, Freie Universitaet Berlin, Carl-Heinrich-Becker-Weg 6-10, Berlin, 12165
Germany
AU: Cubasch, U
EM: cubasch@zedat.fu-berlin.de
AF: Institute for Meteorology, Freie Universitaet Berlin, Carl-Heinrich-Becker-Weg 6-10, Berlin, 12165
Germany
AB:
The Eemian was the last interglacial prior to the Holocene and is linked to
marine isotope stage (MIS) 5e. We present multi-centennial climate simulations
of the Eemian and the subsequent glacial inception. These simulations were
performed with the coupled ocean-atmosphere general circulation model ECHO-G (atmosphere model ECHAM 4 at
T30 resolution coupled to the HOPE-G ocean model at T42). The simulations are performed as equilibrium experiments with
orbital parameters and greenhouse
gas concentrations set to values of 125,000 and 115,000 years before present (BP). These dates represent periods with
enhanced and weakened seasonal cycles
of insolation on the northern hemisphere. Comparisons with pollen-based
reconstructions of European temperatures show that the model simulates
realistic spatial temperature patterns for the warm phase of the Eemian (GRL,
2005, L11703). Especially winter temperatures are affected by changes in
atmospheric circulation and Arctic sea ice coverage. The reduction in summer
insolation at 115,000 years BP leads to a perennial snow-coverage over parts
of North America, which is continuously expanding during the simulated period of 3000 years. This is connected with a
continuous increase of Arctic sea ice volume and a long-term global cooling trend. Consistent with geological records the
snow accumulation starts in north-eastern Canada. In this region southward winds transport cold Arctic air into the
continent. The accumulation of snow on the North American continent is equivalent to a decrease in oceanic sea level at a
rate of 18 cm/century at the end of the simulation.
In summary, in these simulations orbitally-induced changes in insolation are sufficient to explain
the reconstructed temperature patterns as well as to trigger the onset of a glaciation.
DE: 1620 Climate dynamics (0429, 3309)
DE: 1621 Cryospheric change (0776)
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3344 Paleoclimatology (0473, 4900)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005