HR: 15:10h
AN: C43D-07    [Abstracts]
TI: Variability and evolution of $\delta^{18}$O$_{precip}$ in a Coupled Atmosphere Ocean GCM
AU: * LeGrande, A N
EM: legrande@ldeo.columbia.edu
AF: NASA/GISS and Columbia University | Center for Climate Systems Research, 2880 Broadway, New York, NY 10034 United States
AU: Schmidt, G
EM: gschmidt@nasa.giss.giv
AF: NASA/GISS and Columbia University | Center for Climate Systems Research, 2880 Broadway, New York, NY 10034 United States
AU: Thresher, D
EM: dthresher@nasa.giss.gov
AF: University of Bremen, Postfach 330 440, Bremen, 28334 Germany
AU: Hoffman, G
EM: hoffmann@lsce.saclay.cea.fr
AF: L.S.C.E, D.S.M., Orme des Merisiers C.E. Saclay,, Gif-sur-Yvette, 91191 France
AB: Variability and evolution of $\delta^{18}$O$_{precip}$ in a Coupled Atmosphere Ocean GCM The newest version of the GISS coupled GCM (modelE) tracks water isotopes through every step of the hydrologic cycle. As such, we have a unique ability to monitor the affect of oceanic and atmospheric conditions on $\delta^{18}$O$_{water}$ and $\delta$D. We assess the intrinsic spatial and temporal variability of coupled water isotopes in the ocean and atmosphere under modern conditions. We examine the isotopic response to forced climate changes, including results from an abrupt climate change scenario where we simulate the 8.2 ka event by forcing the coupled model with an isotopically depleted freshwater input at high latitude. In addition, we include coupled model water isotope results given glacial boundary conditions. We assess natural and forced climate influences on $\delta^{18}$O$_{precip}$ on seasonal, annual, decadal, and multi-decadal timescales. We infer the interplay between the various factors that control $\delta^{18}$O$_{precip}$ given different rates of climate change and different boundary conditions. Preliminary results from the 8.2 ka event show the same magnitude of isotopic depletion as observed in Greenland ice cores and the Ammersee record. Interestingly, these results suggest that temporal $\delta^{18}$O$_{precip}$ - temperature relationships are influenced by the nature of the climate change.
DE: 4842 Modeling
DE: 4870 Stable isotopes
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting